Municipal Solid Wastes and Their Disposal

Transcription

1 Environmentl Helth Perspectives Vol. 27, pp , 1978 Municipl Solid Wstes nd Their Disposl by Rlph Stone* A brief overview is given of the sources, chrcteristics, nd toxic constituents of municipl solid wstes. Severl methods re presented for hndling, treting, nd disposl of solid wstes. Monitoring the lndfill site is necessry; there hs been trend to recognize tht municipl solid wstes my be hzrdous nd to provide seprte secure hndling, tretment, nd disposl for their dngerous constituents. Under current stte nd Federl regultions, permits re being required to ssure tht proper hndling of conventionl solid wstes nd more hzrdous constituents re crefully mnged. Introduction Municipl solid wstes re generted from residentil, commercil, nd industril sources. These solid wstes, exclusive of process type wstes nd sludges, re usully mixed together in collection vehicles nd re highly compctible. As shown in Tble 1, they contin heterogeneous conglomertion of diverse constituents disposed of by our society (1), including newsprint, crdbord, nd other miscellneous pper nd wood products; plstics; grden trimmings nd brush; food (grbge); textiles; glss; cns; metl; products of building demolition; street sweepings; sphlt; concrete; mnures; furniture; ded nimls; nd so forth. Municipl solid wstes lso often contin ll sorts of hzrdous nd toxic wstes such s pthogens from hospitls or homes; pesticides nd herbicides from public prks nd privte grdens; combustibles such s crbide, gsoline, oil, grese, nd sh residues from industril, commercil, or residentil sources; wste explosive mterils such s smll rms; spry or pint continers; industril chemicls, both orgnic nd inorgnic, nd ll types of cid nd lkli sludges; wstewter tretment residues such s septic tnk, nd sewge tretment plnt sludges; feces from children's disposble dipers; ded nimls; nd so forth. A brekdown of typicl solid wste genertion sources reported for the Stte of Pennsylvni, including n estimte of the quntity of hzrdous wstes generted, re listed in Tble 2. This tble indictes tht in Pennsylvni, pproximtely 5% of the totl solid wste quntities re hzrdous. Tble 3 lists some * Rlph Stone nd Compny, Inc., Snt Monic Boulevrd, Los Angeles, Cliforni December 1978 mjor industril plnts nd their toxic wste sources nd constituents. Hzrdous or toxic wstes re defined s mterils which re dngerous to humn helth nd the environment. They cn be responsible for poisoning, burning, or otherwise injuring or destroying people or other living orgnisms. Hzrdous wstes my ct immeditely upon being ingested; they cn ffect the nervous system, my be crcinogenic, or cn result in birth defects. Some toxic constituents re not biodegrdble nd cn persist in the wter, ir, or lnd, indefinitely. Toxic mterils my ccumulte in living orgnisms including the food supply. Pthogenic orgnisms, oxygen demnd, nd toxic elements or compounds re commonly present to some degree in ny municipl solid wste, nd my pose substntil dnger to humn, niml, nd plnt life. As result of incresing recognition of these problems, there is trend towrd more Federl, stte, nd locl governmentl requirements for proper hndling nd disposl of solid wstes. Discussion Originlly, municipl solid wstes were commonly disposed of by open dumping, open burning, or incinertion. Open dumping cn contribute to lnd litter nd wter pollution, nd the end products of open burning nd incinertion cn contribute to ir pollution in the form of prticultes, nitrogen oxides, noxious odors, nd other constituents. In ddition, the burning process cn produce solid residues which when ultimtely disposed cn contribute to wter pollution nd even help to crete some smll mounts of methne gs. Municipl incinertion with sophisticted energy recovery sys- 239

2 Tble 1. Composition of municipl solid wstes. Composition (wet weight), % Ctegory of wste Ocensideb Los Angeles" Snt Clrd Long Isln& Ntionl vergef Pper Newsprint Crdbord Miscellneous pper Totl Food Glss nd cermics Metls Totl vegettion (tree nd shrub-prunings, grss & leves) Textiles Rubber, lether, plstics Hrd rubber, lether, plstics Fom rubber nd plstic Totl Wood Soil, concrete, rock, sh Dirt, snd, sh Concrete, rock Totl Other (2 in. sieve) 9.4 Dt of Stone (1). b Composite of four qurterly smples tken during c Los Angeles, Cliforni (wet weight) s received 1/14/71 (88 loeds). d Snt Clr, Cliforni (2). e Long Islnd, New York (suburbn, similr to Ocenside) (3). f Dt of Hickmn (4). Tble 2. Sold wste genertion in Pennsylvni. Residuls generted yerly Million dry metric tons (Tg), (estimted) Mining nd minerl wstes 33.5 Industril wstes 18.2 Agriculturl wstes 24.5 Municipl wter nd wstewter 0.6 tretment wstes Demolition wstes 1.8 Privte, municipl, nd commercil refuse 9.1 Totl wste generted 87.7 Estimtes of hzrdous wste genertion Dt of Merritt nd Glid (5). tems were populr in lrge Europen nd Americn cities t the turn of the century, but becme extinct due to high operting costs. Similrly, in former yers, grbge ws reclimed for hog feed; niml wstes were rendered for fts to mnufcture sop nd other products. These prctices hve become less populr becuse of public helth requirements to sterilize grbge, nd becuse of the economies of mixed refuse collection. However, the recovery of pper, metls, nd other solid wstes continues to be prcticed by scrp delers whenever economiclly fesible. In recent yers, municipl solid wste incinertion hs become less populr becuse of gretly incresed ir pollution control requirements. Snitry lndfills hve become predominnt s methods for disposl of municipl solid wste. The snitry lndfill ws first ntionlly pplied in Gret Britin during World Wr II s low cost wy of controlling litter nd other undesirble open-dumping conditions. Snitry lndfills re normlly defined s solid wste sites receiving dily 6-in. (15 cm) fresh, clen soil cover over compcted refuse generlly plced in 5- to 20-ft (1.5- to 6-m) depth cells. The soil covet minimizes flies nd rodents by restricting their ccess to or escpe from the orgnics present in the refuse. The soil cover lso helps to bury litter nd serves s rod bse for the disposl vehicles which will dischrge dditionl wste in the next lift. The erth cover lso restricts ir movement nd prevents fires. A finl soil cover, 2 ft deep or more, is plced on the top lift of lndfill to control infiltrting wter, grow vegettion, nd enble the use of the completed site for other purposes. The design of snitry lndfills involves multiple professionl disciplines nd requires specilized 240 Environmentl Helth Perspectives

3 Tble 3. Industril wste types. Code Stndrd industril No. clssifiction Wste type Composition 20 Food nd kindred products Cnning Trimming wstes Orgnics Met Orgnics Grin mills Residues Acids 22 Textile products Wool, synthetics, cotton 26 Pper nd llied products 28 Chemicls nd llied plstics, Synthetics Sops, detergents Pints, vrnishes Chemicls, fertilizers 29 Petroleum refining 31 Lether nd lether products 32 Stone, cly, concrete 33 Primry metls 34 Fbricted metls 35 Electricl utilities Dt of Merritt nd Glid (5). Preprtion sludges, pulping, sludges wste liquor, fly sh, filter ckes, fly sh prticultes, slg, mining nd milling fibers, pickling liquors Slg Slimes nd tilings Annodizing sludges, chromting sludges, phosphting sludges, glvnizing sludges, electroplting sludges Prticultes, sludges Acids, lklis, metl slts, phenols, oxidizers, dyes, flmmble solvents Sulftes, orgnics, sops, sulfites, mercptns Zinc, slts, brines, phenols, cids Surfctnts, polyphosphtes, luminum, copper, nd chrome oxides Metl slts, other toxics Sulfuric, phosphoric cids, orgnic phosphorus, copper sulfte, mercury rsentes, spent cids Spent cids, spent custics, hydrocrbons, metllic slts, cyclic intermedites Chrome slts, oils, dyes, orgnics, cids Sulfur, mmoni chlorides, phenols, cynide, oils, chrome, lklis, cids Oxides, sulfur, iron Copper, zinc, led, luminum Metllic slts, cids, oils, lklis, evnides Fly sh, sulfur dioxide knowledge of hydrology, geology, biology, gronomy, chemistry, nd engineering. The decomposition of lndfilled solid wstes generlly occurs in n nerobic environment. Dringe of wter through lndfill cn produce lechte contining ll types of orgnic nd inorgnic dissolved compounds. These lechte constituents cn pollute the receiving groundwter or surfce wter. A summry of representtive dt on initil lechte composition derived from municipl solid wste is shown in Tble 4. Lrge quntities of combustible methne gs, s well s inert crbon dioxide, re continuously generted by orgnic decomposition in snitry lndfills. Methne gs is explosive when present in ir in the rnge of 5-15% by volume; it is odorless nd does not dissolve significntly in wter. The methne gs hs been known to migrte severl thousnd feet from snitry lndfill, nd to cuse severe explosions in buildings, sewers, nd other structures. Anlysis of typicl lndfill gs constituents is shown in Tble 5. Engineering clssifiction of disposl sites bsed on the locl geology, hydrology, topogrphy, nd the types of wstes is described in Tble 6. This clssifiction ws originlly developed by the Stte of Cliforni Wter Pollution Control Bord, Los Angeles Region. Clss 1 lndfill sites re locted in nonwter-bering loctions which re not connected with groundwter nd cn, therefore, re- December

4 Tble 4. Composition of initil lechte from municipl solid wste. Composition, mg/i.b Study A Study B Component Low High Low High ph Hrdness, CCO Alklinity, CCO C Mg N K Fe (totl) Ferrous iron 8.7c 8.7c Chloride % Sulfte Phosphte Orgnic N NH4N BOD 21,700 30,300 COD ,715 Zn Ni Suspended solids 13 26,500 Dt of Brunner nd Keller (6). b Averge composition, mg/l. of first 1.3 liters of lechte per cubic foot of compcted, representtive, municipl solid wste. c One determintion. Time intervl since strt Tble 5. Lndfill gs composition. Content, verge % by volume of cell completion, months N2 CO2 CH Dt of Brunner nd Keller (6). ceive ll types of solid wste, including toxic or hzrdous mterils. Norml municipl wstes re disposed of into so-clled Clss 2 sites locted less thn specified minimum distnce bove ny potentil groundwter tble (commonly 3 m). Mterils disposed into Clss 2 or 3 lndfil site should not contin hzrdous or toxic industril wstes. Provisions re mde for monitoring the subsurfce groundwter for lechte pollution. In most res of the semirid western United Sttes the rinfll is not sufficient enough to sturte snitry lndfill when proper surfce dringe is engineered to void concentrtion nd percoltion into the lndfill. Diversion drins nd impervious or sloped surfces re used to prevent lechte in ll 242 types of disposl sites. Clss 3 disposl sites re used solely for reltively more inert type solid wstes such s construction refuse, demolition rubble, broken concrete nd sphlt, erth, nd street sweepings. In the lst few yers there hs been concern bout developing specil fcilities for lndfiling segregted hzrdous wstes in secure re. The secure lndfils should provide for seprtion of incomptible hzrdous wstes-for exmple, chemicls which cn cuse dngerous rections re not mixed but, rther, re seprted in fenced nd lined bsins to prevent fires, explosions, or other hzrds tht my occur s result of chemicl or biochemicl rections. Secure lndfills my hve double liners with monitoring wells to test tht there re no leks in the lining; in ddition, they my be provided with collection sumps to store ny possible under-dringe. Negtive dringe creted by perimeter brriers nd interior collection wells cn lso support fil-sfe lechte controls. Secure res should be doublefenced nd posted. In ddition, on-site lndfill fcilities my hve tretment works for neutrliztion of cid nd lkli wstes. The segregtion of unmixed solid wste or sludge residues lso llows for their reclmtion by employing the reltively pure wste residue s rw mteril for new products. For exmple, some oily wstes my be reclimed s fuel. Specil vehicles should be used to hul nd unlod hzrdous wstes t secure lndfills. The vehicles should crry mnifests which describe the chemicl nlysis of the hzrdous wstes crried, the quntities, the originl owner, the disposl loction, nd, if necessry, proper hndling nd lndfl disposl procedures. Secure lndfills, s well s other clsses of lndfils should hve provisions for perpetul site mintennce nd environmentl monitoring to void future pollution or lnd use problems. Perpetul site mintennce my be provided by public gencies or by suitble privte trust funds. In ddition to the trend towrd improved solid wste engineering, tretment, control, monitoring, nd mintennce prctices, there hs lso been incresed concern with the helth nd sfety of personnel hndling municipl solid wstes. Solid wste collection nd disposl hs been trditionlly one of the most dngerous occuptions in the United Sttes. Under the Federl Occuptionl Sfety nd Helth Act there hs been greter impetus to protect employees from ccidents, wether, nd flying debris. Uncontrolled public scvenging of solid wstes is now in disfvor becuse of the helth nd sfety hzrds tht my be ssocited with solid Environmentl Helth Perspectives

5 Tble 6. ClssifIction of disposl sites. Clss Chrcteristics Wstes cceptble for disposl t clss disposl siteb Clss I Sites locted on nonwter-bering rocks or No limittion s to either solid or Clss II Clss III underlin by isolted bodies of unusble groundwter, which re protected from surfce runoff nd where surfce dringe cn be restricted to the site or dischrged to suitble wstewy, nd where sfe limittions exist with respect to the potentil rdius of percoltion Sites underlin by usble, confined, or free groundwter when the minimum elevtion of the dump cn be mintined bove nticipted high groundwter elevtion, nd which re protected from surfce runoff nd where surfce dringe cn be restricted to the site or dischrged to suitble wstewy Sites so locted s to fford little or no protection to usble wters of the stte liquid wstes Limited to ordinry household nd commercil refuse nd other rubbish, grbge, decomposble orgnic refuse, nd scrp metl of the nture indicted below t sfe elevtions bove nticipted high groundwter elevtion in the vicinity of the site: Empty tin cns Metls Pper nd pper products Cloth nd clothing Wood nd wood products Lwn clippings, sod, nd shrubbery Hir, hide nd bones Smll ded nimls Roofing pper nd tr pper Thoroughly quenched shes from high temperture incinertors Unquenched shes mixed with refuse Mrket refuse Grbge All mteril cceptble t Clss III without regrd to elevtion of nticipted high groundwter Limited to nonwter-soluble, nondecomposble inert solids of the nture indicted below Erth, rock, grvel, nd concrete Asphlt pving frgments Glss Plster nd plsterbord Mnufctured rubber products Steel mill slg Cly nd cly products Asbestos shingles Americn Public Works Assocition clssifiction (7). b This list is not intended to be complete or comprehensive but rther n indiction of the nture of wstes cceptble t ech clss of disposl site. Mterils other thn those listed my be considered seprtely by the interested governmentl gencies nd the Regionl Wter Pollution Control Bord. wste mterils. The U. S. Environmentl Protection Agency 208 plnning elements will influence future solid wste mngement since solid wstes include point sources, intermittent, nd non-point sources of pollution. Comprehensive wter qulity plnning requires tht both physicl (structurl), nd mngement (nonstructurl) techniques be used to control wter pollution t existing nd nticipted future soil wste sites. Nonpoint sources of solid wste include griculture, silvculture, bndoned nd ctive mines, construction nd run-off from completed structures, subsurfce wste disposl in wells nd excvtions, slt wter intrusion, hydrologic modifiction, onsite sewge lnd disposl, diffused sources from wste type lnd disposl prctices nd ir qulity chnges tht my result in "cid rin" or other fllout. The first purpose of the 208 plnning elements is to develop lterntive pollution control methods for municipl nd other solid wstes. To ccomplish this tsk, n inventory of the extent of solid wste is first required. Secondly, coordinted re-wide December

6 solid wste pln must be developed under n overll stte progrm. The third ctivity is to estimte the future solid wste lod bsed on projected popultion, use, economic ctivities, nd required wter nd ir pollution control requirements. The fourth step is to evlute the control nd surveillnce progrms for monitoring the solid wste. The fifth step is to estblish priorities for the different ctegories of individul solid wste ccording to their pollution impcts, s well s their economic nd socil effects. The lst nd sixth step is to estblish solid wste pollution control schedule for ll point source nd non-point source solid wstes for implementing the btement progrm. Permits re being required to enforce the locl, Stte nd Federl government solid wste progrm. Municipl solid wste mngement is similr in economic mgnitude to wter, sewge, or power utilities. In the United Sttes, over 6 lb (2.7 kg) per cpit per dy, tht is, more thn 2000 lb (900 kg) of municipl solid wste per cpit per yer, re generted. With the incresed requirements for clen ir nd wter, even more solid wste will be disposed to the lnd. Municipl solid wstes re now recognized s n importnt source of hzrdous pollutnts tht must be properly controlled. The recent federl solid wste legisltion in Public Lw , entitled the Resource Conservtion nd Recovery Act of 1976 (8). A mjor provision under Subtitle C is concerned with hzrdous wste mngement. Hence in the future even greter emphsis will be plced on regulting hzrdous solid wste in the municipl nd other source strems. REFERENCES 1. Rlph Stone nd Compny, Inc. Disposl of Sewge Sludge Into Snitry Lndfill. EPA SW-71d Rlph Stone nd Compny, Inc. Underground incinertion of solid wstes. Report, U. S. Public Helth Service Grnt G06-EC-00190, July Kiser, E. Therml processes for refuse reduction. Pper presented t APWA, Institute for Solid Wstes, Annul Meeting, Boston, Mss., Oct. 1-5, Hickmn, H. L., Jr. Chrcteristics of municipl solid wstes. Scrp Age, Feb Merritt, G. L., nd Glid, G. R. Overview of residuls mngement in Pennsylvni. Lnd Appliction of Residul Mterils. Proceedings Engineering Foundtion Conference. Eston Mrylnd, September 26-October 1, 1976, Americn Society of Civil Engineers, New York. 6. Brunner, D. R., nd Keller, D. J. Snitry lndfill design nd opertion. EPA Publiction, SW-65 ts, U. S. Government Printing Office, Wshington, Americn Public Works Assocition. Municipl Refuse Disposl, 2d ed., Interstte Printers nd Publishers, Dnville, Ill., Resource Conservtion nd Recovery Act of 1976 nd Title II-Solid Wste Disposl, Public Lw , 94th Congress, Oct. 21, Environmentl Helth Perspectives