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1 Mastertitelformat bearbeiten Training Material

2 Training Material. This training material contains the most important issues for planning decentralised wastewater treatment plants in developing countries. It is based on the book: Decentralised Wastewater Treatment in Developing Countries. Its philosophy might be described with the slogans on the next page.

3 Learnings

4 Learnings. Wastewater is treated by applied science, not by propaganda What will not be maintained, does not need to be built Only freaks like to handle wastewater Dissemination of is different from selling proprietary articles like cell phones

5 Decentralised Wastewater Treatment Systems

6 Intro. includes only such systems which are considered suitable for decentralised application and dissemination in the case that qualified maintenance and operation cannot be expected

7 Intro. There are certain measures at hand to discharge effluent of acceptable quality provision of sufficient space at the source of pollution pre-treatment at source and post treatment where sufficient land is available pre-treatment at source and post treatment in cooperation with others accepting an effluent with higher pollution load restricting wastewater producing activities at this particular site connection to a central treatment plant via sewage line

8 Intro. Fully centralised system Lowest construction cost per volume of wastewater Up to five times the cost for the required sewerage Management costs are comparatively low Maintenance costs are quite high Semi-centralised system Construction costs are relatively low Costly management may be needed for each plant Fully decentralised system Requires capable natural environment for discharge Structural costs are likely to be the lowest Requires sludge disposal at site, or costly transportation Maintenance and management costs are negligible Centralised service and supervision may be required

9 Philosophy

10 Philosophy. is based on reliability, longevity, tolerance towards inflow fluctuation, and no need for sophisticated control and maintenance. work without technical energy, and thus cannot be switched off intentionally. provides treatment for wastewater flows from m³ per day, from both domestic and industrial sources.

11 Why Wastewater Treatment?

12 Why Wastewater Treatment? What are the benefits of wastewater treatment? What kind of wastewater can be treated? Which problems can be solved by treating wastewater?

13 Treatment

14 Treatment. Treatment means stabilisation of pollutants via oxidation removal of solids removal of harmful substances (N,P, toxins)

15 Treatment. Stabilisation is a matter of degradation of organic compounds; it is predominantly a matter of oxidising carbon (C) to carbon dioxide (CO 2 ), nitrogen (N) to nitrate (NO 3 ), phosphorus (P) to phosphate (PO 4 ) sulphur (S) to sulphate (SO 4 ). hydrogen (H) to water (H 2 O).

16 Treatment. Aerobic, anoxic and anaerobic decomposition O 2 C 6 H 12 O 6 + 6O 2 CO 2 + 6H 2 O chemical and bio-chemical degradation with or without bacteria O aerobic respiration free oxygen comes from outside the wastewater anoxic respiration oxygen comes from other substances within the wastewater (here NO 3 ) C 6 H 12 O 6 + 4NO 3 6CO 2 + 6H 2 O + 2N 2 bio-chemical degradation through bacteria anaerobic fermentation no additional oxygen; substances are split by bacteria into compounds, compounds are re-aranged C 6 H 12 O 6 3CH 4 + 3CO 2 bio-chemical degradation through bacteria

17 Ingredients of life. Biological wastewater treatment happens through bacteria. Wastewater is the feed of bacteria. The bodies of bacteria consist of H, C, O, N, S, P and trace elements. Bacteria can only multiply as far as those substances are present in wastewater. C S trace elements N H P O

18 Ingredients of life. C S trace elements N H P O Proteins contain all the necessary elements. A favourable proportion between C, N, P and S (varying around a range of 50: 4: 1: 1). Carbohydrates and fats are composed of C, O and H and cannot be fermented in pure form.

19 Treatment. Principle of the anaerobic process Organic matter + water carbohydrate proteins lipids hydrolysing Bacteria fatty acids acetogenic bacteria acetate hydrogen carbohydrate metanogenic bacteria methane + carbon dioxide methane + water water + mineralised sludge + bacteria mass Karstens / Berthe-Corti

20 Treatment. carbohydrates oxidation of carbon citric acid cycle organic matter + oxygen proteins enzymes dehydration / hydration respiration of carbon enzymes splitting water + mineralised sludge + bacteria mass

21 Treatment. easily degradable enzymes for decomposition are immediately available difficult degradable enzymes have first to be produced by bacteria.

22 Treatment. Aerobic is fast. Anaerobic is slow. The bacterial population, which is responsible for easy degradation tends to predominate over the others. To protect the "weaker" (slower) bacteria one may separate different bacterial populations in phases. In case of, it is easiest to provide longer retention times so that the "slow" bacteria find their food after the "quick" bacteria have consumed theirs.

23 Treatment. Anaerobic treatment of wastewater from: City sewage Distilleries Breweries Canneries Yeast production Coffee processing Milk processing Food processing Starch production Sugar factories Organic chemicals production Slaughter houses Animal and human excreta Paper mills

24 Treatment. organic nitrogen and / or N present in different forms aerobic or anoxic conditions kjeldahl nitrogen ammonia nitrogen NH 3 Nitrification from outside or other substances nitrate nitrogen + O = NO 3 Denitrification anaerobic conditions become anoxic to other substances that attract oxygen into atmosphere NO 3 - O = N 2

25 Treatment. Phosphorous compounds remain potential phosphate suppliers. Phosphorus is removed with the bacteria mass in form of settled sludge.

26 Treatment. Complete Wastewater Treatment with removal of easily settleable solids removal of easily degradable organic solids Sedimentation begin of anaerobic fermentation of bottom sludge possible Anaerobic digestion mineralisation of suspended or dissolved organic compounds, biogas production settling of mineralised particles, collection and ventilation of biogas Aerobic and facultative decomposition removal of sludge removal of sludge removal of easily and more difficult degradable solids mineralisation of suspended or dissolved organic compounds settling of mineralised particles removal of sludge Post treatment removal of suspended digested solids and active bacteria mass settling of finest suspended solids, removal of algea retaining of living and dead algea removal of sludge Other treatment steps, such as the removal of toxic materials, stripping of ammonium, etc., are not part of the concept.

27 Treatment Systems. Sedimentation Anaerobic digestion sedimentation pond anaerobic filter septic tank biogas digester anaerobic baffled reactor planted gravel filter Aerobic and facultative decomposition Post treatment aerobic-facultative ponds and aerobic polishing ponds Other systems such as UASB, sequencing batch reactors, rotating discs, activated sludge reactors, etc. do currently not belong to

28 Treatment. Area requirements of treatment plants: septic tank, Imhoff tank: 0,5 m²/m³ daily flow anaerobic filter: baffled septic tank: constructed wetland: 1 m²/m³ daily flow 1 m²/m³ daily flow 30 m²/m³ daily flow anaerobic ponds: 4 m²/m³ daily flow facultative aerobic ponds: 25 m²/m³ daily flow

29 Treatment. Combined system: UASB (foreground), settler (centre), sediment sludge biogas digester and sludge storage tank (background) (Thailand, Uni Chiang Mei, GTZ)

30 Treatment. Anaerobic Biogas Digesters at Fushan Farm. The pond receives digested sludge for feed of fish. (Zhejiang Province, P.R. China, HRIEE)

31 Treatment. Imhoff tank followed by planted gravel filter and polishing pond (Auroville, Tamil Nadu, India, CSR)

32 Treatment. Space is often a problem in industrial estates. (Noida, Uttar Pradesh, India, SIITRAT)

33 Coarse and fine screens should be avoided whenever feasible Treatment. Screening is unavoidable in case of poultry wastewater

34 Ecology

35 Ecology. Even this little stream should stay clean

36 Ecology. The biological self-purification effect of surface waters depends on: climate (temperature) and relative pollution load. The presence of free oxygen is a precondition for the self-purification process.

37 Ecology. 1,8 1,6 1,4 Oxygen intake via surface contact factor 1,2 1 0,8 0, temperature in C

38 Ecology. faktor kr 0,6 0,5 0,4 0,3 0,2 Ability of surface waters to recover oxygen after pollution 0,1 0 pond lake slow river medium f ast river fast river cascades after Garg

39 Ecology. Nutrients from wastewater increase algae growth in receiving waters. Too many algae turn the water dark and green. Thus, algae do not produce, but consume oxygen. Supply of free oxygen decreases. Aquatic life is affected. Nutrients should return to the nutrient cycle: irrigation of agricultural production, gardening.

40 Ecology. Chlorine disinfects wastewater. Chlorine does also disinfect the receiving waters. Disinfected water is dead water. Therefore: save chlorine!

41 Ecology. Effluent from paper mills is one of the most polluting and difficult wastewaters (P.R. China)

42 Parameters

43 Parameters. Data required to design daily wastewater flow times or periods of major wastewater flow or other data describing fluctuations and maximum flow average COD values and range of fluctuation average BOD values or average COD/BOD ratio suspended solids content, percentage of settleable solids ph ambient temperature and temperature of wastewater at source

44 Parameters. Total solids in wastewater inorganic solids (ash) volatile (organic) solids inorganic solids (ash) water

45 Parameters. Hydraulic load (weak wastewater) m³/m³ * d wastewater volume per reactor volume per day m³/m² * d wastewater volume per surface area per day Organic load (strong wastewater) kg/m³ * d organic mass (BOD, COD) per reactor volume per day kg/m² * d organic mass (BOD, COD) per surface area per day

46 total oxygen demand COD - oxygen demand that can be captured by a defined chemical analysing method total oxygen demand COD BOD if all matter is biodegradable: à BOD = COD BOD - total oxygen demand of biodegradable substances Parameters. if all matter is biodegradable within 5 days: à BOD 5 = BOD BOD 5 BOD 5 - part of the BOD that can be captured by a defined biological analysing method within 5 days. The Oxygen Demand is the unit that measures the weight of oxygen which is required to stabilise polluting matter. It is mostly measured in mg/l

47 Treatment Systems

48 Treatment Systems. Organic loading rates, treatment efficiency and optimum temperature of various treatment systems typical values aerobic ponds maturation ponds water hyacinth ponds anaerobic ponds anaerobic filters baffled reactors loading rates (BOD 5 kg/m³*day) 0,11 0,01 0,07 0,3-1,2 4,00 6,00 efficiency (BOD 5 removed) 85% 70% 85% 70% 85% 85% temperature optimum 20 C 20 C 20 C 30 C 30 C 30 C different sources

49 Treatment Systems. 100% 90% 80% 70% 60% 50% 40% Composition of domestic wastewater settl. solids susp. solids diss. solids BOD org. DM min DM diss. solids susp. solids settl. solids 30% 20% 10% 0% BOD org. DM min DM organic dry matter mineral dry matter

50 Treatment Systems. % of total 1,2 1 0,8 0,6 0,4 0,2 0 Removal rates in settling tests of domestic wastewater SS TS BSB CSB ,25 61% 32% 15% 10% 0,5 85% 45% 19% 12% 0,75 90% 57% 21% 15% 1 95% 63% 23% 16% 1,5 98% 69% 26% 17% 2 100% 73% 28% 20% 3 100% 77% 32% 23% 4 100% 80% 35% 25% 5 100% 80% 36% 28% 6 100% 80% 36% 30% 7 100% 80% 36% 30% settling time in hours SS TS BSB CSB

51 Treatment Systems. Principle of the Septic Tank 1. Sedimentation and floatation 2. Fermentation of bottom sludge

52 Treatment Systems. Characteristics of the Septic Tank kind of treatment: sedimentation, sludge stabilisation, COD rem 20-50% type of wastewater: domestic and others with settleable solids advantages: simple, durable, underground, area required: 0,5m²/m³ wwpd disadvantages: only pre-treatment, effluent not odourless

53 Treatment Systems. urs COD removal rate 60% 50% 40% 30% 20% 10% COD removal rates in settlers COD rem. factor 0 0% 1 27% 3 40% 30 55% 40 55% 0% settling time in hours

54 Treatment Systems. 100% 75% 50% months sludge 0 100% 36 50% % Reduction of sludge volume during storage 25% 0% months

55 Treatment Systems. Principle of the Imhoff-Tank 1. Sedimentation 2. Protection against upflow of sludge particles 3. Fermentation of bottom sludge Floatation outside funnel Sedimentation inside funnel cross section longitudinal section manhole liquid flow tank 1 2 scum inflow outflow 3 sludge

56 Treatment Systems. Imhoff-Tank before placing the cover (Auroville, Tamil Nadu, India, CSR)

57 Treatment Systems. Characteristics of the Imhoff-Tank kind of treatment: sedimentation, sludge stabilisation, COD rem 20-50% type of wastewater: domestic and others with settleable solids advantages: simple, durable, underground, odourless effluent, area required: 0,5m²/m³ wwpd disadvantages: less simple than septic tank, needs very regular desludging

58 Treatment Systems. Principle of the Anaerobic Baffled Reactor 1. Sedimentation/floatation of solids 2. Anaerobic digestion of suspended & dissolved solids through contact with sludge 3. Anaerobic digestion (fermentation) of bottom sludge 4. Sedimentation of mineralised (stabilised) bottom sludge biogas manholes inflow scum outflow sedimentation clarification primary sludge inoculation of wastewater with active sludge

59 Treatment Systems. Characteristics of the Anaerobic Baffled Reactor kind of anaerobic degradation of suspended treatment: and dissolved solids, COD rem 60-90% type of pre-settled domestic & strong industrial wastewater: wastewater of narrow COD/BOD ratio advantages: simple, reliable and durable, high efficiency, underground, area required: 1 m²/m³ wwpd disadvantages: larger space during construction, less efficient with weak wastewater, longer time for maturation

60 Treatment Systems. factor 120% 100% 80% 60% 40% COD removal rate in relation to HRT in Baffled Reactors HRT(h) BODrem 0 0% 5 51% 10 82% % % 20% 0% HRT in hours

61 Treatment Systems. factor 100% 80% 60% 40% 20% Comparing Efficency of Baffled Reactor and fully Mixed Reactor 0 0% 0 0,42 82% 1 0,84 94% 2 1,04 100% % % % % 100 0% HRT in days baffled fully mixed

62 Treatment Systems. 1,20 1,00 Influence of number of up-flow chambers on COD removal in Baffled Reactors 1 0,40 2 0,70 3 0,90 8 1,2 factor 0,80 0,60 0, number of chambers

63 Treatment Systems. 1,2 1 Influence of wastewater strength on treatment efficiency in anaerobic Baffled Reactors factor 0,8 0,6 0,4 strengths 0 0, , , , , , , BOD mg/l

64 BORD Treatment Systems. Principle of the Anaerobic Filter 1. Sedimentation/floatation of solids 2. Anaerobic digestion of suspended and dissolved matter inside the filter 3. Anaerobic digestion (fermentation) of bottom sludge gas manhole inflow scum outflow sludge sedimentation tank filter units

65 Treatment Systems. Anaerobic filter under construction (Chengdu, Sichuan, P.R.China, CEEIC)

66 Treatment Systems. Anaerobic filter constructed underground (Chengdu, Sichuan, P.R.China, CEEIC)

67 Treatment Systems. Characteristics of the Anaerobic Filter kind of anaerobic degradation of suspended treatment: and dissolved solids, COD rem 65-85% type of pre-settled domestic and industrial wastewater: wastewater of narrow COD/BOD ratio advantages: simple and durable if well constructed, high treatment efficiency, underground, area required: 1 m²/m³ wwpd disadvantages: costly in construction because of filter material, clogging possible, effluent smells slightly

68 Treatment Systems. 1,20 1,00 Influence of temperature on COD removal in Anaerobic Filters Temeprature COD removal rate 10 0, , , , ,10 factor 0,80 0,60 0, temperature in C

69 Treatment Systems. factor 1 0,8 0,6 0,4 m²/m³ COD removal in relation to filter surface in Anaerobic Filters % COD removal 0 0 1, % 1, % 1, % 1, % 1,06 1,000 0, specific filter surface m²/m³

70 Loose plastic rings Cinder Bamboo rings Treatment Systems. Corrugated plastic sheets Rock / Gravel Plastic bottle cleaners or soft filling Filter Material for Anaerobic Baffled Reactor

71 O 2 O 2 BORDA Treatment Systems. Principle of the Vertical Filter 1. submerged for equal distribution of wastewater through flush charging 2. oxygen follows the percolating wastewater by vacum effect 3. oxygen is available for decomposition during resting time plants keep filter surface porous waste water flooded with wastewater fine sand O 2 O 2 O 2 O 2 coarse sand O 2 O 2 O 2 coarse gravel ventilated channel

72 Treatment Systems. Vertical filter: 1. bed charged by flooding, 2. bed at rest (D. Esser)

73 Treatment Systems. There is never equal distribution without flooding (D. Esser)

74 Treatment Systems. Principle of the Horizontal Filter 1. continuous oxygen supply to the upper layers only 2. anaerob-facultative conditions in the lower layers 3. roots of plants provide favourable environment for bacteria diversity O 2 O 2 O 2 O 2 internal water level inflow manhole upper sand layer central outlet shaft final outlet cross distribution trench filled with rocks main filter body filled with coarse gravel cross collection trench filled with rocks perforated pipe connected to swivel pipe for adjustable height

75 Treatment Systems. Horizontal filter and polishing pond for a bungalow (Auroville, Tamil Nadu, India, CSR)

76 Treatment Systems. Characteristics of the Horizontal Gravel Filter kind of aerobic-facultative-anaerobic degradation treatment: of dissolved and fine suspended solids, COD rem 60-95% type of wastewater: suitable for pre-treated domestic and weak industrial wastewater advantages: high treatment efficiency when properly designed and constructed, pleasant landscaping possible, no wastewater above ground, no nuisance of odour disadvantages: large permanent space, costly, difficult construction, experienced supervision required in the beginning, area required: 30m²/m³ wwpd

77 Treatment Systems. Darcy's Law cross sectional area of filter bed [m²] = A c = Q s kf * dh / ds flow rate [m³/sec] hydraulic conductivity [m/sec] x slope [m height/m length]

78 Treatment Systems. Influence of Grain Size and Grain Shape on Filter Properties Ø 25 mm pore space 22,1 % max pore size 2,8 mm spec. surface 143 m²/m³ Ø 5 mm pore space 45,7 % max pore size 0,6 mm spec. Surface 652 m²/m³ Ø 5 mm (5%) and Ø 25 mm (95%) pore space 23,9 % max pore size 1,6 mm spec. Surface 164 m²/m³ mixed grain size mixed grain shape pore space and pore size unpredictable

79 Treatment Systems. factor 1,4 1,2 1 0,8 0,6 0,4 Relation between treatment efficiency and HRT in Planted Gravel Filters rembod HRT factor 60% 0,45 70% 0,53 75% 0,61 80% 0,7 85% 0,83 90% 1,01 95% 1,31 60% 65% 70% 75% 80% 85% 90% 95% treatment efficiency (BOD rem. rate)

80 Treatment Systems. HRT in days Influence of temperature on HRT in Planted Gravel Filters temp HRT (90% rem. Effic) temperature in C

81 Treatment Systems. Principle of Treatment Ponds

82 Treatment Systems. Aerobic-facultative pond at a rice mill (SIITRAT, Delhi)

83 Treatment Systems. Characteristics of the Anaerobic Pond kind of sedimentation, anaerobic degradation, treatment: sludge stabilisation, COD rem 50-70% type of wastewater: strong and medium industrial wastewater advantages: simple in construction, flexible degree of treatment, little maintenance disadvantages: occupies open land, can be stinky, difficult mosquito control, area required: 4m²/m³ wwpd

84 Treatment Systems. Characteristics of Aerobic Pond kind of aerobic-facultative degradation, treatment: pathogen reduction, COD rem 60-95% type of wastewater: advantages: weak, pre-treated domestic and industrial wastewater simple in construction, reliable if properly designed, high pathogen removal rate, fish farming possible disadvantages: large permanent space requirement, mosquitoes and odour can become a nuisance if undersized, algae can increase effluent BOD, area required: 25m²/m³ wwpd

85 Treatment Systems. BOD g/m²*d Max. organic load in relation to temperature in Aerobic-Facultative Ponds temp BOD g/m*d 10 7,5 17, temperature in C

86 Treatment Systems. Long canals covered with water cabbage for final treatment of effluent (Fushan Farm, Zhejiang Province, P.R. China, HRIEE)

87 Treatment Systems. Principle of Sludge Drying Bed charging of sludge splash plate 30 cm free board for sludge 15 cm sand 30 cm gravel rocks drain

88 Treatment Systems. Sludge truck in Yuhang (Zhejiang Province, P.R. China, HRIEE)

89 Biogas Utilisation

90 Biogas Utilisation. Biogas Potential of Wastewater theoretical constant 350 l methane per 1 kg BOD removed practical use 200 l biogas per 1 kg COD removed

91 Biogas Utilisation. factor 120% 100% 80% 60% 40% 20% 0% COD removal rates in relation to HRT in fully mixed digesters 0 0% 5 40% 10 75% 15 90% 20 95% 25 98% % % HRT in days

92 Biogas Utilisation. Principle of Fixed Dome Biogas Plant 1.A) Original charging B) In operation after all gas had been used 2. In Operation, gas storage completely full, highest gas pressure

93 Biogas Utilisation. annual pro annual profit Profit on additional cost for biogas use at 80% COD removal rate inflow COD mg/l

94 Biogas Utilisation. Spherical dome digester under construction (Tanzania, CAMARTEC)

95 Biogas Utilisation. Anaerobic filter for biogas production of tofu effluent (Zhejiang Province, P.R. China, HRIEE)

96 Dissemination

97 Dissemination. First recognise the problem, then think of possible solutions Wastewater treatment may be only a part of a whole package of measures required in a given situation

98 Dissemination. There are certain measures at hand to discharge effluent of acceptable quality: provision of sufficient space at the source of pollution pre-treatment at source and post treatment where sufficient land is available pre-treatment at source and post treatment in cooperation with others accepting an effluent with higher pollution load restricting wastewater producing activities at this particular site connection to a central treatment plant via sewage line.

99 Dissemination. A dissemination strategy has to observe: the social aspect the economic aspect the technical aspect the legal aspect

100 Dissemination. Local adaptation of is influenced by: the technical requirements and solutions the geographical or physical environment the social and socio-economic circumstances

101 Dissemination. The best maintenance could not make good for an originally faulty construction

102 Dissemination. Treatment cost are influenced by: the degree and the kind of water pollution the degree and kind of treatment the chosen treatment system the applied level of technology the degree of reusing water, sludge and biogas the management system the legal discharge standard and fees

103 Dissemination. The objectives of organising people may be manifold: collecting investment capital, contributing land, giving permission for trespassing of sewers collective operation and maintenance collective financing of services for operation reuse of effluent or biogas.

104 Dissemination. Concepts, which require the participation of the general public, are not likely to work too well, and consequently, should be avoided whenever possible, unless a demand responsive approach is adopted.