Approved baseline and monitoring methodology AM0080

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1 Approved baselne and montorng methodolog AM0080 Mtgaton of greenhouse gases emssons wth treatment of wastewater n aerobc wastewater treatment plants I. SOURCE, DEFINITIONS AND APPLICABILITY Sources Ths methodolog s based on the followng submsson: NM0250: Fès Waste Water Treatment Plant (WWTP) wth sludge treatment and bogas recover & utlzaton for electrct generaton at Fès ct, Morocco. Ths methodolog also refers to the latest approved versons of the followng tools: Combned tool to dentf the baselne scenaro and demonstrate addtonalt ; Tool to determne project emssons from flarng gases contanng methane ; Tool to calculate the emsson factor for an electrct sstem ; Tool to calculate baselne, project and/or leakage emssons from electrct consumpton ; Tool to calculate project or leakage CO 2 emssons from fossl fuel combuston. For more nformaton regardng the proposed new methodologes and the tools as well as ther consderaton b the Executve Board please refer to < Selected approach from paragraph 48 of the CDM modaltes and procedures Exstng actual or hstorcal emssons, as applcable ; or Emssons from a technolog that represents an economcall attractve course of acton, takng nto account barrers to nvestment. Defntons For the purpose of ths methodolog, the followng defntons appl: Anaerobc dgester. In an anaerobc dgester the bodegradable fracton of sludge or wastewater s converted nto CH 4 and CO 2 b a complex of bactera. These gases (bogas) are collected n a controlled wa. Several desgns of anaerobc dgesters are possble. The bogas can be used for electrct producton, for heatng purposes, or t can be flared. Aerobc wastewater treatment plant. Wastewater treatment plant that operates under manl aerobc condtons, based on the actvated sludge process. The actvated sludge process comprses prmar and secondar treatment stages. The prmar treatment ncludes screenng, grt chamber and prmar sedmentaton tank, and the secondar treatment s based on the recrculaton of actvated sludge. The secondar treatment s where the substantal degradaton of the bologcal content takes place. A dagram of the plant s presented n Annex 1. 1/38

2 Anaerobc open lagoons sstem. Sstem of lagoons and ponds where wastewater s treated b a complex of bactera under manl anaerobc condtons. Applcablt Ths methodolog s applcable to project actvtes that mplement a new aerobc wastewater treatment plant for the treatment of domestc and/or ndustral wastewater. The sludge produced n the aerobc wastewater treatment plant n the project actvt s ether: (1) Treated n the same wa as the sludge that would have been produced n the anaerobc open lagoons sstem n the baselne scenaro would have been treated. Ths ncludes one of the followng two optons: () the sludge s dumped or left to deca; or () the sludge s dred under controlled and aerobc condtons, and then dsposed to a landfll wth methane recover or used n sol applcaton; or (2) Treated n a new anaerobc dgester, wth the bogas extracted from the anaerobc dgester beng flared and/or used to generate electrct and/or heat. The resdues from the anaerobc dgester are dehdrated, lmed and stored before fnal dsposal n a controlled landfll. Project partcpants should document n the CDM-PDD ther specfc case and clearl descrbe (a) the stuaton before the mplementaton of the project actvt, (b) the stuaton under the project actvt and (c) the stuaton n the baselne scenaro, b provdng dagrams. The followng condtons appl: The project actvt ether replaces an exstng anaerobc open lagoons sstem, wth or wthout converson of the sludge treatment sstem, or s an alternatve to a new to be bult anaerobc open lagoons sstem; Loadng n the wastewater streams has to be hgh enough to ensure that the exstng or new to be bult anaerobc open lagoons sstem develops an anaerobc bottom laer and that algal oxgen producton can be ruled out; The average depth of the exstng or new to be bult anaerobc open lagoons sstem s at least 1 meter. In case of an exstng anaerobc open lagoons sstem n the baselne scenaro, the depth of the lagoons should be verfed based on hstorcal data avalable for one ear before the mplementaton of the project actvt. In case of a new to be bult anaerobc open lagoons sstem, the depth of the lagoons should be determned followng the gudance provded n Step 1 of the secton Procedure for the dentfcaton of the most plausble baselne scenaro and assessment of addtonalt ; The resdence tme of the organc matter n the anaerobc open lagoons sstem s at least 30 das. In case of an exstng anaerobc open lagoons sstem n the baselne scenaro, the resdence tme of the organc matter n the lagoon should be verfed based on hstorcal data avalable for one ear before the mplementaton of the project actvt. In case of a new to be bult anaerobc open lagoons sstem, the resdence tme of organc matter n the lagoons should be determned followng the gudance provded n Step 1 of the secton Procedure for the dentfcaton of the most plausble baselne scenaro and assessment of addtonalt. 2/38

3 Fnall, ths methodolog s onl applcable f the most plausble baselne scenaro, as determned b the Procedure for the dentfcaton of the most plausble baselne scenaro and assessment of addtonalt further below n ths methodolog, s that: The wastewater would have been treated n an exstng (W3) or new to be bult (W6) anaerobc open lagoons sstem under clearl anaerobc condtons and wthout methane recover and flarng; The sludge that would have been produced n the baselne lagoons sstem would have been dumped or left to deca (S1), or dred under controlled and aerobc condtons and then dsposed to a landfll wth methane recover or used n sol applcaton (S2); The electrct produced wth bogas n the project scenaro, f an, would have been produced usng fossl fuels n a captve power plant (E1), or obtaned from the grd (E2); The heat produced wth bogas n the project scenaro, f an, would have been produced usng fossl fuels n a captve cogeneraton power plant (H1), or usng fossl fuels n a boler (H2). II. BASELINE METHODOLOGY Project boundar The spatal extent of the project boundar ncludes: The ste and facltes where the wastewater and sludge are treated n both the baselne and the project scenaro; An on-ste power plants that suppl electrct to the wastewater and sludge treatment sstems; An on-ste facltes that generate heat used b the wastewater and sludge treatment sstems; If applcable, the anaerobc dgester, the power and/or heat generaton equpment and/or the flare nstalled under the project actvt; If grd electrct s dsplaced from electrct generaton wth bogas from an aerobc dgester: the power plants connected to the grd, wth the geographcal boundar as specfed n the latest approved verson of the Tool to calculate the emsson factor for an electrct sstem. The emsson sources ncluded n the project boundar are descrbed n Table 1 below. Table 1: Emsson sources ncluded n the project boundar Source Gas Justfcaton / Explanaton Baselne Wastewater and sludge treatment CH 4 Included Major source of emssons n the baselne. N 2 O Excluded Excluded for smplfcaton. Ths s conservatve. CO 2 Excluded CO 2 emssons from the decomposton of organc waste are not accounted for. 3/38

4 Project Actvt Electrct and thermal energ generaton Transportaton of sludge Wastewater and sludge treatment On-ste use of electrct and fossl fuels Transportaton of sludge CO 2 Included Emssons from electrct/thermal energ generaton n the baselne scenaro arse from: () Electrct/thermal energ used for the operaton of the baselne wastewater/sludge treatment sstems; () Electrct/thermal energ dsplaced b bogas based electrct/thermal energ generated n the project actvt, f an. CH 4 N 2 O Excluded Excluded for smplfcaton. Ths s conservatve. Excluded Excluded for smplfcaton. Ths s conservatve. CO 2 Included Emssons from transportaton of sludge ma be ncluded. CH 4 Excluded Excluded for smplfcaton. Ths s conservatve. N 2 O Excluded Excluded for smplfcaton. Ths s conservatve. CH 4 Included Major source of emssons n the baselne. CO 2 Excluded CO 2 emssons from the decomposton of organc waste are not accounted for. N 2 O Included In case of projects that nvolve land applcaton of sludge ths s an mportant emsson source. CO 2 Included Ma be an mportant emsson source. CH 4 N 2 O Excluded Excluded for smplfcaton. Ths emsson source s assumed to be ver small. Excluded Excluded for smplfcaton. Ths emsson source s assumed to be ver small. CO 2 Included Emssons from transportaton of sludge ma be ncluded. CH 4 N 2 O Excluded Excluded for smplfcaton. Ths emsson source s assumed to be ver small. Excluded Excluded for smplfcaton. Ths emsson source s assumed to be ver small. Procedure for the dentfcaton of the most plausble baselne scenaro and assessment of addtonalt Project partcpants shall determne the most plausble baselne scenaro and assess the addtonalt of the proposed project actvt usng the latest verson of the Combned tool to dentf the baselne scenaro and demonstrate addtonalt agreed b the CDM Executve Board. The specfc gudance descrbed below should be used when applng the referred steps of the tool. 4/38

5 Step 1: Identfcaton of alternatve scenaros The plausble alternatve scenaros for wastewater and sludge treatment should be chosen so as to meet the water and sludge qualt standards defned n the applcable legslaton. Plausble alternatve scenaros for the treatment of wastewater (W) should be determned. These ma nclude, but are not lmted to, the followng: W1: Drect release of wastewaters to a nearb water bod; W2: Aerobc wastewater treatment facltes (e.g., actvated sludge or flter bed tpe treatment); W3: Exstng anaerobc open lagoons sstem wthout methane recover and flarng; W4: Exstng anaerobc open lagoons sstem wth methane recover and flarng; W5: Exstng anaerobc open lagoons sstem wth methane recover and utlzaton for energ generaton; W6: New to be bult anaerobc open lagoons sstem wthout methane recover and flarng; W7: New to be bult anaerobc open lagoons sstem wth methane recover and flarng; W8: New to be bult anaerobc open lagoons sstem wth methane recover and utlzaton for energ generaton; W9: Anaerobc dgester wthout methane recover and flarng; W10: Anaerobc dgester wth methane recover and flarng; W11: Anaerobc dgester wth methane recover and utlzaton for electrct or heat generaton. Plausble alternatve scenaros for the treatment of sludge (S) should be determned. 1 but are not lmted to, the followng: These ma nclude, S1: The sludge would have been dumped or left to deca; S2: The sludge would have been dred under controlled and aerobc condtons, wth dsposal n a landfll wth methane recover or wth use n sol applcaton; S3: Dsposal of sludge n sludge pts under clearl anaerobc condtons; S4: Land applcaton of the sludge; S5: Compostng; S6: Mneralzaton; S7: Dsposal of sludge n a landfll wthout landfll gas capture; S8: Dsposal of sludge n a landfll wth landfll gas capture and flare; S9: Dsposal of sludge n a landfll wth landfll gas capture and utlzaton for energ generaton; S10: Anaerobc dgeston wthout methane recover; S11: Anaerobc dgeston wth methane recover and flarng; S12: Anaerobc dgeston wth methane recover and utlzaton for energ generaton. For the alternatve scenaros nvolvng new to be bult anaerobc open lagoons sstems (.e., W6, W7 and W8), the specfcatons of the plausble alternatve scenaros (ncludng applcable optons for sludge treatment) shall be defned as per the followng steps: 1 Please, note that the sludge beng referred to here s not the sludge (tpe and quantt) produced n the project actvt, but the sludge that would have been produced n the baselne scenaro dependng on the wastewater treatment technologes consdered as plausble alternatve scenaros. 5/38

6 (a) Defne several desgn optons for open lagoons sstems that meet relevant regulatons for treatment of the partcular wastewater stream. Take nto consderaton the local condtons, such as envronmental legslaton, ground water table, land requrement, ambent temperature, etc.. Desgn specfcatons shall nclude average depth and surface area of the lagoons, electrct consumpton, resdence tme of the organc matter and effluent adjustment factor (AD, as defned later on ths methodolog), as well as an other ke parameters. Document the dfferent desgn optons n a transparent manner and provde transparent and documented evdence of ke assumptons and data used. Offer conservatve nterpretatons of ths evdence; (b) Verf the average depth of the desgn optons, as determned n Step (a) above, based on a revew of publshed lterature establshng an average lagoon depth for the partcular tpe of wastewater. If such lterature does not exst, conduct a surve based on a control group of the fve most recentl constructed lagoons sstem n the geographcal area, as defned n the Combned tool to dentf the baselne scenaro and demonstrate addtonalt ; (c) If the average depth of the desgn optons s deeper than the average depth dentfed through lterature revew or the control group n Step (b), provde credble explanatons wh the assumptons of the least cost desgn are vald. The explanatons have to be supported b credble evdences that the depth dentfed n step (b) s not a feasble opton for the project actvt. Provde transparent and documented evdence, and offer conservatve nterpretatons of ths evdence; (d) The DOE undertakng the valdaton shall nclude an ntervew wth an ndependent wastewater expert. Durng the ntervew, the expert shall confrm () the desgn parameters and () the results of the lterature revew or the control group surve. If the project actvt ncludes electrct generaton wth bogas produced n a new anaerobc dgester whch treats the sludge from the aerobc wastewater treatment plant, plausble alternatve scenaros for the generaton of electrct should be determned. These ma nclude, but are not lmted to, the followng: E1: Power generaton usng fossl fuels n a captve power plant; E2: Electrct generaton n the grd; E3: Electrct generaton usng renewable sources of energ. If the project actvt ncludes heat generaton wth bogas produced n a new anaerobc dgester whch treats the sludge from the aerobc wastewater treatment plant, plausble alternatve scenaros for the generaton of heat should be determned. These ma nclude, but are not lmted to, the followng: H1: Heat generaton usng fossl fuels n a captve cogeneraton plant; H2: Heat generaton usng fossl fuels n a boler; H3: Heat generaton usng renewable sources of energ. Identf realstc and credble combnatons of scenaros for wastewater treatment (W), sludge treatment (S), generaton of electrct (E) and generaton of heat (H), as applcable. The suggested lst of alternatves above (W, S, E and H) s ndcatve. Project partcpants ma propose other plausble alternatves and/or elmnate techncall not feasble optons from the lst above, based on documented evdence. Make sure that the proposed project actvt not beng regstered under the CDM s ncluded amongst the realstc and credble combnatons of scenaros. 6/38

7 Step 2: Barrer analss Project proponents cannot appl a barrer analss as descrbed n Step 2 of the Combned tool to dentf the baselne scenaro and demonstrate addtonalt, but wll have to undertake an nvestment analss as descrbed n Step 3. The nvestment analss should take nto account further gudance provded n the step below. 2 Step 3: Investment analss Conduct an nvestment analss as descrbed n Step 3 of the Combned tool to dentf the baselne scenaro and demonstrate addtonalt. The most cost-effectve alternatve (e.g. wth the hghest IRR) should be selected as the baselne scenaro. The followng parameters should be ncluded n the calculaton and be explctl documented: Land cost; Engneerng, procurement and constructon cost; Labour cost; Operaton and mantenance cost; Admnstraton cost; Fuel cost; Captal cost and nterest; Revenue from electrct and/or heat sales; All other costs of mplementng the technolog of the each alternatve opton; All revenues generated b the mplementaton of the proposed technolog except for carbon credts revenues (ncludng energ savngs due to captve use of bogas as fuel for ether electrct or heat generaton at the project ste). For alternatve scenaros nvolvng new to be bult anaerobc open lagoons sstems (.e., W6, W7 and W8), the DOE undertakng the valdaton shall nclude an ntervew wth an ndependent wastewater expert. Durng the ntervew, the expert shall confrm the selecton of the least cost lagoon desgn. Baselne emssons Baselne emssons are estmated as follows: BE BECH4,ww, + BECH4,sl, + BEEL, + BEHG, + BETR, sl, = (1) 2 The reason for a mandator use of an nvestment analss for ths tpe of project actvtes s that aerobc wastewater treatment plants are often used as a preferred opton n stuatons where tght water qualt standards are requred. Under such crcumstances, the use of anaerobc open lagoons sstems could become prohbtvel expensve or even techncall not feasble. Therefore, the assessment of havng anaerobc open lagoons sstems as a credble alternatve to the proposed CDM project actvt depends manl on the costs of both optons based on the project specfc crcumstances (e.g., water standards to be met, land avalablt, etc.). A barrer analss, for example b usng a frst of a knd argument, could result n the project clamng emsson reductons whch never would have been a realstc alternatve to the project actvt. 7/38

8 BE BE CH4,ww, BE CH4,sl, BE EL, BE HG, BE TR,sl, = Baselne emssons n ear (tco 2 e/ear) = Methane emssons from anaerobc treatment of the wastewater n the baselne scenaro n ear (tco 2 e/ear) = Methane emssons from treatment of sludge n the baselne scenaro n ear (tco 2 e/ear) = CO 2 emssons assocated wth electrct generaton that s dsplaced b the project actvt and/or electrct consumpton n the baselne scenaro n ear (tco 2 /ear) = CO 2 emssons assocated wth fossl fuel combuston for heatng equpment that s dsplaced b the project n ear (tco 2 /ear) = CO 2 emssons assocated wth transportaton of sludge n the baselne scenaro n ear (tco 2 /ear) Calculaton of baselne emssons from treatment of wastewater (BE CH4,ww, ) Baselne methane emssons from anaerobc treatment of the wastewater n open lagoons are calculated usng the so-called methane converson factor method descrbed below: BE = GWP B COD MCF (2) CH4, ww, CH4 o BL,ww, BL,ww, BE CH4,ww, = Methane emssons from anaerobc treatment of the wastewater n the baselne scenaro n ear (tco 2 e/ear) GWP CH4 = Global Warmng Potental of methane vald for the commtment perod (tco 2 e/tch 4 ) B o = Maxmum methane producng capact of wastewater, expressng the maxmum amount of CH 4 that can be produced from a gven quantt of chemcal oxgen demand (tch 4 /tcod) COD BL,ww, = Quantt of chemcal oxgen demand that would have been treated n the baselne scenaro n ear (tcod/ear) MCF BL,ww, = Average baselne methane converson factor n ear, representng the fracton of organc load that would be degraded to CH 4 n the baselne scenaro (fracton) Determnaton of COD BL,ww, In prncple, the baselne chemcal oxgen demand (COD BL,ww, ) corresponds to the chemcal oxgen demand that s treated under the project actvt (COD PJ,ww, ) because the wastewater treated under the project actvt would have been drected to the open lagoons n the baselne scenaro, thus: COD = COD (3) BL, ww, PJ,ww, However, f there would be an effluent from the lagoons n the baselne, COD BL,ww, should be adjusted b an effluent adjustment factor whch relates the COD suppled to the lagoon wth the COD n the effluent, as follows: COD = AD COD (4) BL, ww, BL PJ,ww, 8/38

9 COD BL,ww, AD BL COD PJ,ww, = Quantt of chemcal oxgen demand that would have been treated n the baselne scenaro n ear (tcod/ear) = Effluent adjustment factor expressng the percentage of COD that s degraded n open lagoons n the baselne scenaro (fracton) = Quantt of chemcal oxgen demand that s treated n the aerobc wastewater treatment plant n the project actvt n ear (tcod/ear) Determnaton of COD PJ,ww, 12 COD = Q w (5) PJ, ww, m= 1 PJ,ww,m PJ,COD,ww,m COD PJ,ww, Q PJ,ww,m w PJ,COD,ww,m m = Quantt of chemcal oxgen demand that s treated n the aerobc wastewater treatment plant n the project actvt n ear (tcod/ear) = Quantt of wastewater that s treated n the aerobc wastewater treatment plant n the project actvt n month m (m³) = Average chemcal oxgen demand n the wastewater that s treated n the aerobc wastewater treatment plant n the project actvt n month m (tcod/m³) = Months of ear of the credtng perod Determnaton of AD BL If the baselne scenaro s dentfed as beng a new to be bult anaerobc open lagoons sstem (W6), AD BL s determned based on the desgn features that were dentfed usng the procedure outlned n Step 1 of the Procedure for the dentfcaton of the most plausble baselne scenaro and assessment of addtonalt. Opton A below should be used applng the desgn COD nflow for COD BL,n,x and the desgn COD effluent for COD BL,out,x. Otherwse, f the baselne scenaro s dentfed as beng exstng open lagoons (W3), use ether Opton (A) or Opton (B) below to determne AD BL, as applcable: Opton A: In case at least one ear hstorcal data of the COD nflow and COD effluent are avalable, AD BL should be determned as follows: AD BL COD BL,out,x = 1 (6) COD BL,n,x AD BL COD BL,out,x COD BL,n,x x = Effluent adjustment factor expressng the percentage of COD that s degraded n open lagoons n the baselne scenaro (fracton) = COD of the effluent of open lagoons n the baselne scenaro n the perod x (tcod) = COD drected to the open lagoons n the baselne scenaro n the perod x (tcod) = Representatve hstorcal reference perod (at least one ear) 9/38

10 Opton B: In case at least one ear hstorcal data of the COD nflow and COD effluent are not avalable, AD BL should be determned b conductng measurements of the COD nflow to and effluent from the lagoons durng a measurement campagn of at least 10 das. The measurements should be undertaken durng a perod that s representatve for the tpcal operaton condtons of the plant and ambent condtons of the ste (temperature, etc). The average COD BL,n,x and COD BL,out,x values from the measurement campagn shall be used n Opton A and the result shall be multpled b 0.89 to account for the uncertant range (of 30% to 50%) assocated wth ths approach as compared to one-ear hstorcal data. Determnaton of MCF BL,ww, The quantt of methane generated from COD dsposed to the open lagoon depends manl on the temperature and the depth of the lagoon. Accordngl, the methane converson factor s calculated based on a factor f d, expressng the nfluence of the depth of the lagoon on methane generaton, and a factor f BL,T, expressng the nfluence of the temperature on the methane generaton. In addton, a conservatveness factor of 0.89 s appled to account for the consderable uncertant assocated wth ths approach. MCF BL,ww, s calculated as follows: MCF = f f 0.89 (7) BL, ww, BL,d BL,T, MCF BL,ww, = Average baselne methane converson factor n ear, representng the fracton of organc load that would be degraded to CH 4 n the baselne scenaro (fracton) f BL,d = Factor expressng the nfluence of the depth of the lagoon on methane generaton (fracton) f BL,T, = Factor expressng the nfluence of the temperature on the methane generaton n ear (fracton) 0.89 = Conservatveness factor For the purpose of ex ante estmatons, IPCC default values of methane converson factors (MCF) for dfferent treatment tpes and condtons should be used as per IPCC Gudelnes. Determnaton of f BL,T, In some regons, the ambent temperature vares sgnfcantl over the ear. Therefore, the factor f BL,T, s calculated wth the help of a monthl stock change model whch ams at assessng how much COD degrades n each month. Based on monthl values of f T,m the annual value f BL,T, s calculated as follows: f BL,T, = 12 m= 1 12 m= 1 AD f BL T,m Q COD PJ, ww, m BL, avalable, m w PJ, ww, COD, m (8) 10/38

11 f BL,T, f T,m COD BL,avalable,m AD BL Q PJ,ww,m w PJ,COD,ww,m m = Factor expressng the nfluence of the temperature on the methane generaton n ear (fracton) = Factor expressng the nfluence of the temperature on the methane generaton n month m (fracton) = Quantt of chemcal oxgen demand avalable for degradaton n month m (tcod) = Effluent adjustment factor expressng the percentage of COD that s degraded n open lagoons n the baselne scenaro (fracton) = Quantt of wastewater that s treated n the aerobc wastewater treatment plant n the project actvt n month m (m³) = Average chemcal oxgen demand n the wastewater that s treated n the aerobc wastewater treatment plant n the project actvt n month m (tcod/m³) = Months of ear of the credtng perod Determnaton of f T,m The monthl factor to account for the nfluence of the temperature on methane generaton s calculated based on the van t Hoff-Arrhenus approach: f T,m 0 E (T2,m -T = exp R T1 T 1 1 2,m ) f f f T < 283 K 283 K < T T 2, m 2, m 2, m > 303 K < 303 K (9) f T,m = Factor expressng the nfluence of the temperature on the methane generaton n month m (fracton) E = Actvaton energ constant (15,175 cal/mol) T 1 = K ( K + 30 K) R = Ideal gas constant (1.987 cal/k.mol) T 2,m = Average temperature at the project ste n month m (K) m = Months of ear of the credtng perod As ndcated n the equaton above, the value of f T,m cannot exceed 1 and should be assumed to be zero f the ambent temperature s below 10 C. Determnaton of COD BL,avalable,m The quantt of chemcal oxgen demand avalable for degradaton n the open lagoon for each month m, s gven b the balance of the quanttes of wastewater drected to the lagoon, the quantt of organc compounds that deca n the lagoons, and the quantt of an effluent water from the lagoon. Therefore, COD BL,avalable,m s assumed to be equal to the amount of organc matter drected to the open lagoon, less an effluent, plus the COD that ma have remaned n the lagoon from prevous months, as follows: COD = AD Q w + (1- f ) COD (10) BL, avalable,m BL PJ,ww,m PJ,COD,ww,m T,m BL,avalable,m-1 11/38

12 COD BL,avalable,m AD BL Q PJ,ww,m w PJ,COD,ww,m f T,m m = Quantt of chemcal oxgen demand avalable for degradaton n month m (tcod) = Effluent adjustment factor expressng the percentage of COD that s degraded n open lagoons n the baselne scenaro (fracton) = Quantt of wastewater that s treated n the aerobc wastewater treatment plant n the project actvt n month m (m³) = Average chemcal oxgen demand n the wastewater that s treated n the aerobc wastewater treatment plant n the project actvt n month m (tcod/m³) = Factor expressng the nfluence of the temperature on the methane generaton n month m (fracton) = Months of ear of the credtng perod The carr-over calculatons are lmted to a maxmum of one ear. In case the resdence tme n the open lagoon s less than one ear, carr-over calculatons are lmted to the perod where the wastewater remans n the lagoon. In other words, n case the lagoon s empted, the nflow and COD avalable from the prevous month should be set to zero and the accumulaton of organc matter should be started agan. Project partcpants should provde evdence of the tpcal resdence tme of the organc matter n the lagoon. If the baselne scenaro s dentfed as beng a new to be bult anaerobc open lagoons sstem (W6), use the resdence tme of organc matter accordng to the desgn features of the lagoon that was dentfed usng the procedure outlned n Step 1 of the Procedure for the dentfcaton of the most plausble baselne scenaro and assessment of addtonalt. Calculaton of baselne emssons from treatment of sludge (BE CH4,sl, ) If the sludge that would have been produced n the baselne scenaro from the treatment of wastewater n the open lagoons sstem would have been treated b means of controlled drng under aerobc condtons and then dsposed to a landfll wth methane recover or wth use n sol applcaton (S2), the correspondng methane emssons (BE CH4,sl, ) are consdered to be neglgble and are not accounted for. Therefore: BE 0 (11) CH 4, sl, = Ths s conservatve snce ths wll lead to lower baselne emssons. Otherwse, f the sludge that would have been produced n the baselne scenaro from the treatment of wastewater n the open lagoons sstem would have been dumped or left to deca (S1), correspondng methane emssons (BE CH4,sl, ) are calculated as: 16 = (12) 12 BE CH 4, sl, GWPCH 4 F DOCF MCFBL, sl DOCBL, sl QBL, sl, BE CH4,sl, = Methane emssons from treatment of sludge n the baselne scenaro n ear (tco 2 e/ear) 16/12 = Rato between molar mass of methane and molar mass of carbon 12/38

13 GWP CH4 = Global Warmng Potental of methane vald for the commtment perod (tco 2 e/tch 4 ) F = Fracton of methane n the gas. IPCC default value of 0.5 should be used (fracton) DOC F = Fracton of degradable organc content dssmlated to bogas. The IPCC default value of 0.5 should be used (fracton) MCF BL,sl = Methane converson factor for the ste where sludge would have been dumped or left to deca n the baselne (fracton) DOC BL,sl = Degradable organc content of the sludge that would have been produced n the baselne scenaro n ear. IPCC default values should be used: 0.05 for domestc sludge (wet bass, consderng a default dr matter content of 10%) and 0.09 for ndustral sludge (wet bass, assumng dr matter content of 35%) (fracton) Q BL,sl, = Quantt of sludge that would have been produced and treated n the baselne scenaro n ear (tonnes/ear) Determnaton of MCF BL,sl The average baselne methane converson factor for sludge (MCF BL,sl ) should be determned n accordance wth the gudance provded n IPCC 2006 Gudelnes for Natonal Greenhouse Gas Inventores. The same s provded below: Tpe of dsposal ste MCF BL,sl, Anaerobc managed sold waste dsposal stes - These must have controlled placement of waste (.e. waste drected to specfc deposton area, a degree of control of scavengng and a degree of control of fres) and wll nclude at least one of the followng: () Cover materal; () Mechancal compactng; () Levellng of the waste. 1.0 Sem-anaerobc managed sold waste dsposal stes - These must have controlled placement of waste and wll nclude all of the followng structures for ntroducng ar to waste laer: () Permeable cover materal; () Leachate dranage sstem; () Regulatng pondage; (v) Gas ventlaton sstem. 0.5 Unmanaged sold waste dsposal ste (deep and/or wth hgh water table) - Ths comprses of all sold waste dsposal stes not meetng the crtera of managed sold waste dsposal stes and whch have depths of greater than or equal to 5 metres and/or hgh water table at near ground level. Latter stuaton corresponds to fllng nland water, such as pond, rver or wetland, b waste. 0.8 Unmanaged shallow sold waste dsposal stes- Ths comprses all sold waste dsposal stes not meetng the crtera of managed sold waste dsposal stes and whch have depths of less than 5 metres /38

14 Tpe of dsposal ste MCF BL,sl, Uncategorzed sold waste dsposal stes- Onl f the project proponents cannot categorze ther SWDS nto above four categores of managed and unmanaged SWDS, the MCF for ths categor can be used Calculaton of baselne emssons from consumpton of electrct (BE EL, ) In ths step, baselne emssons from the followng sources are estmated: Baselne emssons from consumpton of electrct assocated wth the treatment of wastewater; If electrct s generated wth bogas from a new anaerobc dgester under the project actvt: baselne emssons from the generaton of electrct n the grd (E2) and/or wth a captve fossl fuel fred power plant (E1) n the absence of the electrct generaton wth bogas. As a smplfcaton, project partcpants ma neglect one or both emsson sources. Baselne emssons for the generaton of power n the project actvt and/or consumpton of electrct n the baselne are calculated as follows: EL, ( ECBL, + EGPJ, ) EFBL,EL, BE = (13) BE EL, EC BL, EG PJ, EF BL,EL, = CO 2 emssons assocated wth electrct generaton that s dsplaced b the project actvt and/or electrct consumpton n the baselne scenaro n ear (tco 2 /ear) = Annual quantt of electrct that would be consumed n the baselne scenaro for the treatment of the wastewater and sludge (MWh) = Net quantt of electrct generated n ear wth bogas from the new anaerobc bodgester, f applcable (MWh) = Emsson factor for electrct generated and/or consumed n the baselne scenaro n ear (tco 2 /MWh) = Year of the credtng perod Determnaton of EF BL,EL, To determne the baselne emsson factor for electrct generaton n the baselne, the followng scenaros have to be consdered for the dsplacement of electrct b the project: Scenaro A: Dsplacement of electrct generaton n the grd. The electrct s suppled to/purchased from the grd onl. Ether no captve power plant s nstalled at the ste of electrct consumpton or, f an on-ste captve power plant exsts, t s not operatng or t can not change ts operaton as a result of the project actvt. 3 For uncategorzed sold waste dsposal stes, the IPCC prescrbes an MCF equal to 0.6. For conservatveness reasons, the value 0.4 should be used nstead n ths methodolog. 14/38

15 Scenaro B: Scenaro C: Dsplacement of electrct from (an) off-grd fossl fuel fred captve power plant(s). One or more fossl fuel fred captve power plants are nstalled at the ste of the electrct consumpton source. The captve power plant(s) s/are not connected to the electrct grd. Under the project actvt, no power s fed nto the grd. Dsplacement of electrct from the grd and (a) fossl fuel fred captve power plant(s). One or more fossl fuel fred captve power plants operate at the ste of the project actvt or have been operated pror to the mplementaton of the project and would contnue to operate n the baselne scenaro. The power generaton under the project actvt ma dsplace electrct generaton n both the captve power plant(s) or the grd. Smlarl, electrct demand n the baselne ma be generated b the captve power plan(s) or the grd. For the determnaton of EF BL,EL, the three correspondng scenaros n the latest approved verson of the Tool to calculate baselne, project and/or leakage emssons from electrct consumpton should be appled to calculate baselne emssons from electrct consumpton (BE EC, ). Baselne emssons from the generaton of heat (BE HG, ) Ths step s applcable f the bogas captured from the new anaerobc dgester n the project scenaro s used for heat generaton. If the baselne scenaro for heat generaton s that heat would have been generated usng fossl fuels n a captve cogeneraton plant (H1): 4 BF = 0 (14) HG, If the heat, n the baselne, would have been generated usng fossl fuels n a boler (H2), baselne emssons are calculated as follows: BE HG, HGPJ, EFCO2, FF, heat = (15) η BL, heat BE HG, HG PJ, EF CO2,FF,heat η BL,heat = CO 2 emssons assocated wth fossl fuel combuston for heat producton n the baselne scenaro n ear (tco 2 /ear) = Net quantt of heat generated n ear wth bogas from the new anaerobc dgester (TJ) = CO 2 emsson factor of the fossl fuel used for heat generaton n the baselne scenaro (tco 2 /TJ) = Effcenc of the boler that would be used for heat generaton n the baselne scenaro (fracton) = Year of the credtng perod 4 In case of producton of heat n a cogeneraton plant n the baselne scenaro (H1), the emsson reductons from usng the bogas for heat producton are alread reflected n the emssons related to electrct producton. 15/38

16 Baselne emssons from transportaton of sludge (BE TR,sl, ) The baselne emssons resultng from transportaton of sludge that would have been produced n the baselne scenaro should be calculated as: BE TR, sl, N BL,, DBL, FBL, NCVBL, j EFBL, j = (16) BE TR,sl, N BL,, D BL, F BL, NCV BL,j EF BL,j j = CO 2 emssons assocated wth transportaton of sludge n the baselne scenaro n ear (tco 2 /ear) = Number of trps (vehcle of tpe wth smlar loadng capact) for transportaton of the sludge that would have been produced n the baselne scenaro n ear (trps) = Average dstance per trp, that would have been travelled b the transportaton vehcle of tpe, for transportaton of sludge n the baselne scenaro (km) = Specfc fuel consumpton of the transportaton vehcle of tpe (mass or volume unts of fuel/km) = Net calorfc value of the transportaton fuel j (TJ/mass or volume unts) = CO 2 emsson factor of the transportaton fuel j (tco 2 /TJ) = Vehcle tpe = Fuel tpe used n vehcles = Year of the credtng perod If the emssons assocated wth transportaton of sludge n the baselne scenaro and n the project scenaro are found to be comparable (.e. wthn +1% range) or emssons n the project scenaro are lower, then both can be excluded n the calculaton of baselne emssons and project emssons as a smplfcaton. Determnaton of N BL,, The number of trps of the transportaton vehcle of tpe s calculated as: N BL, Q BL, sl,, = (17) q BL, N BL,, Q BL,sl, q BL, = Number of trps (vehcle of tpe wth smlar loadng capact) for transportaton of fnal sludge generated b the waste water treatment sstem n the baselne scenaro n the ear (trps) = Quantt of sludge that would have been produced and treated n the baselne scenaro n the ear (tonnes) = Average vehcular capact of the transportaton vehcle of tpe (tonnes/trp) = Year of the credtng perod 16/38

17 Project emssons Project emssons are calculated as follows: PE PECH 4, ww, + PECH4,sl, + PEN 2O, sl, + PEEC, + PEFC, + PETR, sl, = (18) PE PE CH4,ww, PE CH4,sl, PE N2O,sl, PE EC, PE FC, PE TR,sl, = Project emssons n ear (tco 2 e/ear) = Methane emssons from treatment of wastewater n the project actvt n ear (tco 2 e/ear) = Methane emssons from treatment of sludge n the project actvt n ear (tco 2 e/ear) = N 2 O emssons from treatment of sludge n the project actvt n ear (tco 2 e/ear) = Project emssons from electrct consumpton n ear (tco 2 e/ear) = Project emssons from fossl fuel consumpton n ear (tco 2 e/ear) = CO 2 emssons assocated wth transportaton of sludge n the project actvt n ear (tco 2 /ear) = Year of the credtng perod Methane emssons from treatment of wastewater (PE CH4,ww, ) Project emssons due to wastewater treatment comprse two components, emssons from the aerobc wastewater treatment plant due to nadequate operaton and/or overloadng, and emssons due to the presence of degradable organc carbon n the treated wastewater after leavng the aerobc wastewater treatment plant: PE CH 4, ww, PECH 4, wwtp, + PECH 4, effl, = (19) PE CH4,ww, PE CH4,wwtp, PE CH4,effl, = Methane emssons from treatment of wastewater n the project actvt n ear (tco 2 e/ear) = Methane emssons from the aerobc wastewater treatment plant n ear due to nadequate operaton and/or overloadng (tco 2 e/ear) = Methane emssons due to the presence of degradable organc carbon n the effluent from the aerobc wastewater treatment plant n ear (tco 2 e/ear) Methane emssons from the aerobc wastewater treatment plant PE CH4,wwtp, Although aerobc wastewater treatment plants are desgned to operate under aerobc condtons, thereb resultng n neglgble emssons of methane, the IPCC recognzes that several factors ma render an aerobc wastewater treatment plant to develop anaerobc condtons durng operaton, thereb resultng n emssons of methane whch cannot be dsregarded. The IPCC gudelnes propose a set of default values for methane converson factors (MCF) n aerobc treatment plant, rangng from 0 to 0.4, dependng on plant management as follows: 17/38

18 Well managed plants (some CH4 can be emtted from settlng basns and other pockets): the default MCF value s 0 (range 0-0.1); Not well managed plant: the default MCF value s 0.4 (range 0-0.4). Those MCF ranges are desgned to account for dfferent operatonal problems whch can arse n aerobc treatment sstems, and subsequentl lead to the development of anaerobc condtons and the converson of a fracton of the organc matter to CH4 rather than to CO2 (.e. anaerobcall rather than aerobcall). Factors whch nfluence wastewater treatment plants operaton n ths context nclude: General hdraulc desgn and operaton: most wastewater treatment plants are desgned to maxmse gravt flow and mnmse the need for mechancal pumpng (due to operatonal costs of pumpng). Whatever the approach adopted, the desgn must mantan full flow and mxng of the wastewater through the dfferent treatment unts (e.g. prmar sedmentaton tanks, aeraton tanks, secondar clarfers/fnal settlement tanks), as well as wthn connectng channels and ppework. Poor desgn can lead to the development of dead zones.e., areas where partculates accumulate, whch, f left untreated, ma lead to the formaton of anaerobc condton, and subsequentl CH4 emssons; Hdraulc short-crcutng (n actvated sludge plants, boflter plant): excessve buld up of sludge, or the formaton of large sludge flocks or flamentous algae can lead to sludge bulkng wthn treatment unts, whch can result n hdraulc short-crcutng.e. condtons where the wastewater passes through the plant at hgher than desgn rates. In boflter plants, blocked nozzles on rotor dstrbuton arms can also lead to lead to poor dstrbuton of wastewater, and create sludge buld ups n the flter matrx. The lack of mxng n the areas where sludge has bult up can result n anaerobc condtons developng, and thus the formaton of CH4; Loadng: loadng of unt processes s a ke desgn consderaton for wastewater treatment plants. Overloadng of a plant can lead to both poor hdraulc condtons evolvng, and poor performance of the bologcal treatment processes as the resdence tme n the treatment unts s not suffcent to allow the bactera to breakdown organc matter. Large varatons n flow to the plant, coupled wth poor plant szng, can augment these problems. Shock loads can also lead to temporar reductons n plant performance, whch can result n the development of plant rregulartes as descrbed prevousl; Mxng and aeraton effcenc (actvated sludge plants and oxdaton dtches): good mxng, ether through surface aeraton of dffuse aeraton sstems, s crtcal to sstem effcac and to mantan suffcent dssolved oxgen (DO) levels n the aeraton tank for the gven level of load; Development of anaerobc mcro-envronments wthn boflocs: under certan crcumstances, development of a bulk sludge can lead to the evoluton of mcro-anaerobc envronments wthn sludge flocs, whch n turn can gve rse to the development of mcro anaerobc communtes, whch can lead to CH4 formaton. These condtons can also arse under normal operatons, and operatonal practces to avod sludge bulkng, such as chemcal addton, can be undertaken; Frequenc of desludgng/sludge wastng: approprate rates of desludgeng of tanks s crtcal to avod excessve sludge buld up wthn treatment unts, whch can lead to anaerobc condtons developng wthn the tank sludge blanket. Desludgng s also mportant to mantan the correct F/M rato. Due to the hghl ste specfc nature of the factors leadng to the development of anaerobc condtons n aerobc wastewater treatment plants, t s dffcult to provde a clear-cut procedure and montorng parameters to determne CH 4 emssons for plants under nadequate operatonal condtons. Ths 18/38

19 methodolog apples a prox parameter, the oxdsaton rato (OR) descrbed further below. In order to conservatvel account for emssons, the hgher value (MCF=0.4) of the IPCC MCF range for aerobc treatment plant should be used f the oxdsaton rato (OR) s out of an acceptable range. If the oxdsaton rato s wthn the acceptable range, emssons should be consdered zero. Therefore, methane emssons from the aerobc wastewater treatment plant n ear due to nadequate operaton and/or overloadng should be calculated as follows: 0, f OR 0.8 = 365 PE CH 4, wwtp, (20) ( ) < GWPCH 4 Bo 0.4 CODPJ, ww, CODPJ, effl,, f OR 0.8 = 1 PE CH4,wwtp, = Methane emssons from the aerobc wastewater treatment plant n ear due to nadequate operaton and/or overloadng (tco 2 e/ear) OR = Oxdsaton rato, representng the rato between organc matter n the output and organc matter n the nput of the aerobc wastewater treatment plant n da of ear (fracton) GWP CH4 = Global Warmng Potental of methane vald for the commtment perod (tco 2 e/tch 4 ) B o = Maxmum methane producng capact of wastewater treated n the ear, expressng the maxmum amount of CH 4 that can be produced from a gven quantt of chemcal oxgen demand (tch 4 /tcod) 0.4 = Default methane converson factor (MCF) for not well managed plants (fracton) COD PJ,ww, COD PJ,effl, = Quantt of chemcal oxgen demand that enters the aerobc wastewater treatment plant n the project actvt n the da of ear (tcod) = Quantt of chemcal oxgen demand n the effluent of the wastewater treatment plant n the project actvt n the da of ear (tcod) Determnaton of the quanttes of chemcal oxgen demands (COD PJ,ww, and COD PJ,effl, ) The quanttes of chemcal oxgen demands n the wastewater and effluent are calculated as follows: COD COD PJ, ww, PJ, effl, = Q = Q PJ, ww, PJ, effl, w w PJ, COD, ww, PJ, COD, effl, (21) COD PJ,ww, Q PJ,ww, w PJ,COD,ww, COD PJ,effl, = Quantt of chemcal oxgen demand that enters the aerobc wastewater treatment plant n the project actvt n the da of ear (tcod) = Quantt of wastewater that s treated n the aerobc wastewater treatment plant n the project actvt n da of ear (m³) = Average chemcal oxgen demand n the wastewater that s treated n the aerobc wastewater treatment plant n the project actvt n da of ear (tcod/m³) = Quantt of chemcal oxgen demand n the effluent of the wastewater treatment plant n the project actvt n the da of ear (tcod) 19/38

20 Q PJ,effl, w PJ,COD,effl, = Quantt of effluent that leaves the aerobc wastewater treatment plant n the project actvt n da of ear (m³) = Average chemcal oxgen demand n the effluent that leaves the aerobc wastewater treatment plant n the project actvt n da of ear (tcod/m³) Determnaton of the oxdsaton rato (OR ) The determnaton of whether the aerobc wastewater treatment sstem s well operated (managed) or not s made b montorng the qualt of the wastewater at the outlet of the treatment plant to make sure t meets the target specfed n the proposed desgn of the proposed CDM project actvt. If t does meet ths requrement t can be trusted to be a well managed faclt wth lttle to no CH4 emssons durng the project mplementaton. Ths approach s consdered as approprate, but the followng two problems are often encountered: In man developng countres the urban areas ether do not have separate storm water dran sstems or the storm water dran sstems do not work properl. Due to ths reason, durng ran seasons, the wastewater gets dluted from the ngress of ranwater before reachng the treatment plant. Because of the dluton effect, the COD n the wastewater decreases and can appear wthn the acceptable range even f the treatment plant s not n operaton; The legslaton n man of the developng countres specfes the maxmum lmt for wastewater COD, but the legslaton generall does not specf the partcular wastewater treatment technolog whch should be used to acheve the objectve. It s possble to acheve an acceptable level of COD n the fnal effluent b dlutng t (drectl mxng water to t) just before t s dscharged nto the fnal recevng bod (mostl fresh water streams). To address these two ssues, the followng approach s suggested: OR COD PJ, ww, PJ, effl, = (22) COD COD PJ, ww, OR COD PJ,ww, COD PJ,effl, = Oxdsaton rato, representng the rato between organc matter n the output and organc matter n the nput of the aerobc wastewater treatment plant n da of ear (fracton) = Quantt of chemcal oxgen demand that enters the aerobc wastewater treatment plant n the project actvt n the da of ear (tcod) = Quantt of chemcal oxgen demand n the effluent of the wastewater treatment plant n the project actvt n the da of ear (tcod) Methane emssons due to the presence of degradable organc carbon n the effluent PE CH4,effl, The methane emssons due to the presence of degradable organc carbon n the effluent from the aerobc wastewater treatment plant are calculated as: 365 PE = GWP B MCF COD (23) CH 4, effl, CH 4 o PJ, effl, = 1 PJ, effl, 20/38

21 PE CH4,effl, = Methane emssons due to the presence of degradable organc carbon n the effluent from the aerobc wastewater treatment plant n ear (tco 2 e/ear) GWP CH4 = Global Warmng Potental of methane vald for the commtment perod (tco 2 e/tch 4 ) B o = Maxmum methane producng capact of wastewater treated n the ear, expressng the maxmum amount of CH 4 that can be produced from a gven quantt of chemcal oxgen demand (tch 4 /tcod) MCF PJ,effl, = Average methane converson factor n ear, representng the fracton of organc load n the effluent that s degraded to CH 4 n ear. The factor s based on the tpe of treatment and dscharge pathwa of the effluent of the aerobc wastewater treatment plant (fracton) COD PJ,effl, = Quantt of chemcal oxgen demand n the effluent of the wastewater treatment plant n the project actvt n the da of ear (tcod) = Year of the credtng perod Determnaton of MCF PJ,effl, The methane converson factor s calculated based on a factor f PJ,d, expressng the nfluence of the depth and a factor f PJ,T, expressng the nfluence of the temperature on the methane generaton. In addton, a conservatveness factor of 0.89 s appled to account for the consderable uncertant assocated wth ths approach. MCF PJ,effl, s calculated as follows: MCF MCF BL,effl, f PJ,d, f PJ,T, = f f 0.89 (24) PJ, effl, PJ,d, PJ, T, = Average baselne methane converson factor n ear, representng the fracton of organc load n the effluent that s degraded to CH 4 n ear. The factor s based on the tpe of treatment and dscharge pathwa of the effluent of the aerobc wastewater treatment plant (fracton) = Factor expressng the nfluence of the depth on methane generaton n ear = Factor expressng the nfluence of the temperature on the methane generaton n ear 0.89 = Conservatveness factor For the purpose of ex ante estmatons, IPCC default values of methane converson factors (MCF) for dfferent treatment tpes and condtons should be used as per IPCC Gudelnes. Determnaton of f PJ,T, In some regons, the ambent temperature vares sgnfcantl over the ear. Therefore, the factor f PJ,T, s calculated wth the help of a monthl stock change model whch ams at assessng how much COD degrades n each month. Based on monthl values of f T,m the annual value f PJ,T, s calculated as follows: f 12 m= 1 PJ,T, = 12 m= 1 f T,m Q COD PJ,effl,m w PJ, avalable, m PJ,COD,effl,m (25) 21/38

22 f PJ,T, f T,m COD PJ,avalable,m Q PJ,effl,m w PJ,COD,effl,m m = Factor expressng the nfluence of the temperature on the methane generaton n ear = Factor expressng the nfluence of the temperature on the methane generaton n month m = Quantt of chemcal oxgen demand n the effluent from the aerobc wastewater treatment plant avalable for degradaton n month m (tcod) = Quantt of effluent that leaves the aerobc wastewater treatment plant n the project actvt n month m of ear (m³) = Average chemcal oxgen demand n the effluent that leaves the aerobc wastewater treatment plant n the project actvt n month m of ear (tcod/m³) = Months of ear of the credtng perod Determnaton of COD PJ,avalable,m The quantt of chemcal oxgen demand avalable n the effluent for each month m, s gven b the balance of the quanttes of COD n the effluent, the quantt of organc compounds that deca, and the quantt of fnal effluent. Therefore, COD PJ,avalable,m s assumed to be equal to the amount of organc matter drected to the dscharge pathwa, less fnal effluent, plus the COD that ma have remaned n the dscharge pathwa from prevous months, as follows: COD = Q w + (1- f ) COD (26) PJ, avalable,m PJ,effl,m PJ,COD,effl,m T,m PJ,avalable,m-1 COD PJ,avalable,m Q PJ,effl,m w PJ,COD,effl,m f T,m m = Quantt of chemcal oxgen demand avalable for degradaton n the effluent from the aerobc wastewater treatment plant n month m (tcod) = Quantt of effluent that leaves the aerobc wastewater treatment plant n the project actvt n month m of ear (m³) = Average chemcal oxgen demand n the effluent that leaves the aerobc wastewater treatment plant n the project actvt n month m of ear (tcod/m³) = Factor expressng the nfluence of the temperature on the methane generaton n month m = Months of ear of the credtng perod The carr-over calculatons are lmted to a maxmum of one ear. Methane emssons from treatment of sludge n the project actvt n ear (PE CH4,sl, ) The sludge produced n the aerobc wastewater treatment plant can be treated n the project scenaro b means of one of the followng methods: (1) The sludge s dred under controlled and aerobc condtons, and then dsposed to a landfll wth methane recover or used n sol applcaton; (2) The sludge s dumped or left to deca; (3) The sludge s treated n a new anaerobc dgester, wth the bogas extracted from the anaerobc dgester beng flared and/or used to generate electrct and/or heat. The resdues from the anaerobc dgester after treatment are dehdrated, lmed and stored before fnal dsposal n a controlled landfll. Correspondng project emssons should be calculated accordngl as explaned below. 22/38