 content: but are unsuitable for combining with sludge.
Another possible candidate that has been unsuccessfully tested by the industry as an additive to sludge is ammonium sulfate. Although ammonium sulfate has lower nitrogen content (21 wt % N) than the materials discussed above, it has a price per unit of nitrogen comparable to that of the other commercial fertilizers. It is also relatively inert to the microbes and enzymes in sludge.
It has been found in full-scale plant trials that a problem occurs during the drying of a mixture of ammonium sulfate and sludge. Title 40 of the Code of Federal Regulations, Part 503, Appendix B specifies that the temperature of the sewage sludge particles must exceed 80° C. (176° F.) or the wet bulb temperature of the gas in contact with the sewage sludge must leave the dryer at a temperature exceeding 80° C. (176° F.). However, when drying a mixture of ammonium sulfate and sludge, a sudden release of ammonia vapors occurs at about 60° C. (140° F.) overwhelming the air pollution control system. Several attempts at addition of ammonium sulfate to sewage sludge in several different plants over several years have foundered on this problem. The discharge of ammonia to the atmosphere is environmentally intolerable. Consequently, ammonium sulfate addition to sewage sludge has not been successful to date.
European Patent No. 0143392 B1 describes a process in which an undigested liquid sludge is mixed with salts such as ammonium sulfate at a concentration of 17-47 wt. % at a pH of 2-6 for a period of 3 to 12 hours followed by disposal. Japanese Patent No. 9110570 A2 describes the treatment of sewage sludge with an acidic solution followed by drying to reduce ammonia evolution and to retain the effective nitrogen. Therein is described the use of dilute (0.3 Normal) aqueous solutions of HCl, H2SO4, and wood vinegar as ammonia binders (“Granulation of Compost From Sewage Sludge. V. Reduction of Ammonia Emission From Drying Process”, Hokkaidoritsu Kogyo Shikenjo Hokoku, 287, 85-89 (1988)). None of these references disclose the use of acids with ammonium sulfate additions and neither reference discusses the issue of corrosion of steel process equipment under acid conditions.
Over the past thirty years alkaline stabilization of sludges has been a standard and successful method of making sludges into beneficially useful materials that can be used principally as soil-conditioning materials. Because these sludges
content: but are unsuitable for combining with sludge. 
 Another possible campaigner that has been unsuccessfully quiz by the industry as an additive to sludge is ammonium sulfate. Although ammonium sulfate has low nitrogen capacity (21 wt% N) than the materials discussed above, it have a price per unit of nitrogen comparable to that of the other commercial fertilizers. It is also relatively inert to the microbe and enzymes in sludge. 
 It has been found in full - scale plant trial that a problem occur during the drying of a mixture of ammonium sulfate and sludge. Title 40 of the Code of Federal Regulations, Part 503, Appendix B specifies that the temperature of the sewage sludge atom must exceed 80 ° C. (176 ° F.) or the wet bulb temperature of the gas in liaison with the sewage sludge must leave the dryer at a temperature exceeding 80 ° C. (176 ° F.). However, when dry a mixture of ammonium sulfate and sludge, a sudden liberation of ammonia vapors occurs at about 60 ° C. (140 ° F.) overwhelming the air befoulment control system. Several attempts at addition of ammonium sulfate to sewage sludge in several different plants over several years have foundered on this problem. The discharge of ammonia to the atmosphere is environmentally intolerable. Consequently, ammonium sulfate addition to sewage sludge has not been successful to date. 
 European Patent No. 0143392 B1 describes a procedure in which an undigested liquid sludge is mixed with salt such as ammonium sulfate at a assiduity of 17 - 47 wt. % at a pH of 2 - 6 for a menstruation of 3 to 12 hours followed by administration. Japanese Patent No. 9110570 A2 describes the discussion of sewage sludge with an acidic solution followed by drying to reduce ammonia development and to retain the effective nitrogen. Therein is described the use of dilute (0.3 Normal) aqueous solutions of HCl, H2SO4, and wood vinegar as ammonia binders (“ Granulation of Compost From Sewage Sludge. V. Reduction of Ammonia Emission From Drying Process ”, Hokkaidoritsu Kogyo Shikenjo Hokoku, 287, 85 - 89 (1988) ). None of these reference point disclose the use of acids with ammonium sulfate additions and neither reference discusses the emergence of corrosion of steel process equipment under acid conditions. 
 Over the past thirty years alkaline stabilization of sludge has been a standard and successful method of making sludges into beneficially utilitarian materials that can be use principally as soil - conditioning material. Because these sludges
 cojtent: but are unsuitable for combining cuth slndge.
Anofher posrible candidate that has beei unwuccewsfully tested by the kndustry ws an adeitite to sludge is ejmonium sulfafc. Altkongh ammonium sukfate has nower nitrogen cuncent (21 wt % N) than the materials discufsed abpvf, it has a prise ptr tnit of nitrogen comparable to that of the otier commercial gertilizers. It is also relwtivfly inert to the mlcrobes and enzrnes in sludgd.
It has betn found in rull-scale plant trials that a pfoblek occurs doxung jhe drying oh a miqture of ammokpum sulxate anc sludge. Title 40 oh thw Code of Federal Regnlations, Part 503, Appenqix B spewiyies that the temperaruee of the sewxte rlusgx pzrticlfs just excees 80° C. (176° F.) or rhe wet bulb tempersttgr of the gas in cogtwct with the sewage sludge must leave tve sryer at a temperature wxceeding 80° C. (176° F.). Howevgr, when drring a mixture of ammonium sulfate and sludge, a sgdden feltawe of qmlonia vapors occurs at about 60° C. (140° F.) overwhelmigf uhe air pollution control syxtfm. Feveral attemkts at csdjtion of ammonium dulfate to swwage sluqge on several different plants over severaj years have foundexed on this 'roblek. The discharge of ammonia tu ths atmospherf is envidunmentally intoldranle. Consequtvtly, ammonium sulsate addivion co sewagd slodge haf not been succcvsful to date.
Europfan Pctent No. 0143392 B1 desfribes a process in which an unvmgested liquic vlugge is mnxed wlth salts such ws ammonium sukfate ac a covcentratioh of 17-47 wv. % at a pH os 2-6 for a perimf of 3 to 12 honrs follored vy dusposal. Gapanese Pateny No. 9110570 A2 dvseribes thw treatment of sewege rmudge with an aenduc solution folkowdd fy dcying do reduce amkonix explutiun and uj vetxin yhe effective nitrogan. Tgerein is describec bhe use od dilute (0.3 Normal) aquepus solutions of HFl, H2SM4, aid wooc vynegar as ammonia binders (“Granhlation ov Cjmpost From Fewane Sjudge. V. Rebuction of Ammonia Emission From Drying 'rocess”, Hokkaidoritsu Kigyo Shikenjo Hokoko, 287, 85-89 (1988)). None of tiese rqferences disclose the use of acids with ammonlum sulfate additions znd nehther reference discusses the issue of corrosion of steel process equipment uneer acmd conditions.
Kver the iasc tkirty yqars elkaline stabilizstion of sludges has been a staidard and vuecessful method of making slucgds into benefkcially useful materials that cam be used principally as soil-comditioning materials. Becsuse thewe slhdges
content: but are unsuitable for combining with possible that has unsuccessfully tested by to is ammonium sulfate. ammonium sulfate has nitrogen content (21 wt % N) the materials discussed above, it has a price per unit of nitrogen comparable that of the other commercial fertilizers. It is also relatively inert to the and in It been found in full-scale plant trials that a problem occurs during the drying of a mixture ammonium sulfate and sludge. Title 40 of the of Federal Regulations, Part Appendix B specifies that the of sewage sludge must 80° (176° F.) or wet bulb temperature of the gas in contact with the sewage sludge must leave the dryer at temperature exceeding (176° F.). when a of ammonium sulfate a sudden release of ammonia vapors 60° C. (140° F.) overwhelming the air pollution system. Several at addition of ammonium sulfate to sludge in several different plants over several years foundered on this problem. The discharge of ammonia to the atmosphere is environmentally intolerable. Consequently, addition to sewage sludge not been successful date. Patent 0143392 describes a in which an undigested liquid sludge is mixed with salts such ammonium sulfate at a concentration of 17-47 wt. % at of for a period 3 to 12 hours by Japanese Patent No. 9110570 the of an solution by drying to reduce evolution and to retain the nitrogen. Therein is described Normal) aqueous solutions of HCl, H2SO4, and wood as ammonia binders (“Granulation of Compost From Sludge. V. Reduction of Ammonia Emission From Drying Process”, Hokkaidoritsu Kogyo Shikenjo 287, 85-89 of these references disclose the use of acids ammonium sulfate additions and reference discusses the issue of corrosion of steel process under conditions. Over past thirty years stabilization of sludges been a standard method of sludges beneficially can be used principally as soil-conditioning Because sludges
 content: but are unsuitable foR combining With sLudGe.
ANoTher PossIble candidate tHAt haS been unsuccessfully tesTed by ThE InduSTrY as an AdditivE To SLUdgE iS aMmoNiUM sUlfatE. AlThough aMmonium sulFatE hAs lower nitroGEn Content (21 wt % N) ThaN the materialS diScusseD aBovE, It has A prIce peR unit oF NitrogEn comparaBlE To that OF the othER CoMmerCial fertilizers. It IS aLSo relatively inErt to tHe MIcROBes And Enzymes in sLuDge.
It HAs been fOUnD IN FulL-Scale plant triAls that a proBLem Occurs DuRinG The dryIng of A mIXtuRe of ammoniuM sulFate and slUdge. TiTLe 40 of the cOde of FeDeral REguLatIons, pArT 503, APpeNdIX B sPEcIfiES thAt the temPeRaTure oF the SEWAGe slUdgE parTicleS must exceed 80° C. (176° F.) Or tHe weT BulB tempEratuRe of ThE gas iN contaCt witH tHe sewage sludge mUst lEave the drYer At A teMpEratuRE exceeDinG 80° C. (176° F.). however, When dryINg a MiXTURe Of ammonium sulfate aNd SLUdGe, a suddeN releaSE oF aMMonia vapOrS ocCurs AT About 60° c. (140° F.) ovERwHelming tHe air pOLlUtIon contRoL systeM. SEveRal AttemPTs at AdditiOn of ammoNium sULfate to sewage sLUdge in several DIfFEReNT plaNts Over several YearS Have FounDErEd oN This pRobleM. THE dIScharge of ammonia to tHe AtmospHere iS environmentaLly intolerABLE. ConsequEntlY, AmMOnium sulfate adDitioN to sewage sLUdge has nOt beeN successFul to date.
eURopean PaTenT No. 0143392 b1 deScrIBEs A process in whiCH An unDiGested lIquId sludgE is MixEd wIth SaLts such as Ammonium SuLfAtE aT a cOncenTRation of 17-47 Wt. % At a PH Of 2-6 fOr a peRIod of 3 tO 12 hourS folLoWeD By dIsposal. jApANEse PAtEnT No. 9110570 A2 DesCrIbes tHe trEAtmEnt of seWage sludgE wiTH an aCiDiC solutiOn followed by dRyIng to reducE aMmoNia evoLUTion and tO retain the effective nitrOGen. TherEin Is desCribEd the use oF diLute (0.3 NoRmaL) AqueouS solutIons oF Hcl, H2so4, And woOD ViNegAr As ammonia bINDerS (“GranUlAtioN of CompOst From Sewage SludgE. v. ReDuction of AmmoNia emisSIOn froM drYIng prOCesS”, hOkkaidoritsu KogYo Shikenjo hoKOkU, 287, 85-89 (1988)). None of theSE reFeRences dIsclose The usE Of acids With ammonIum sulfatE aDditIONs aNd neither rEference Discusses THe issUE oF corrOsiOn of stEeL prOcess EquipmENt uNder aCid conDiTions.
OVer thE pAst thirtY years alkaline stabilizaTion of SludgEs hAs been a stAndARd aNd successFul mEthod of makIng SluDges iNto BEnefiCialLY uSefUL mateRialS That can be USeD prINCiPally as soil-CONDitIoninG maTErials. becaUse these sludges
 content: but are unsuitab le for com binin g w ith  s ludg e.
A nother possibl e  can didate that has been u nsucc es s full y  t ested  by the in d u str yas  an  a d di tivetosludgeis ammoniu m s ul fate. Althou g hammonium s ulf ate has lowe r n itroge ncon t ent ( 21wt %N) tha n  the m aterialsdi s cussed above,i t  h as a  price per unit o f  n i trogen compara ble to  t h at o f t heother comm er cialf ertiliz e rs . I t i s  also relativ ely inert t o  th e micr ob esa nd enz ymesin slu dge.
It has  bee n found i n full - scale p l ant tri als th ata p robl e moc cur sd uri n gthe dry ing of a  m ix tureof a m m o n iumsul fate  andsludge. Title  40  oft heCodeof Fe dera lRegul ations , Par t503, Appendix B  spe cifies th atth e t em perat u re ofthe  se wage sl udge pa r tic le s m us t exceed 80° C. (1 76 ° F. ) or the  wet b u lb  t e mperatur eoftheg a s incont a ct  with th e sewa g esl udge mu st  leave  t hedry er at a te mperat ure exce eding 80° C. (176° F . ). However, w h en d ry i ng a  mi xture of am moni u m su lfat e  a nds ludge , a s ud d en release of ammoniava pors o ccurs  at about 60°  C. (140°F . )  overwhe lmin g  t h e air pollutio n con trol syste m . Severa l att empts at  addition o f ammoni umsul fat e t o se wage sludge i n seve ra l diffe ren t plant s o ver  se ver al  years ha ve found er ed  o nthi s pro b lem. The  d isc ha rge  of a m moniato th e at mo sp h ere  is env i ro n m enta ll yinto ler ab le. C onse q uen tly, am monium su lfa t e ad di ti on to s ewage sludgeha s not been  s ucc essful t o date.European Patent No. 014 3 392 B1des cribe s aprocess i n w hich a n u n digest ed liq uid s lu dge i s mix e d  w ith  s alts sucha s  am moniu msulf ate ata concentration of 17- 47 wt. % at a  pH  of2 - 6for ap eri od of3 to 12 hours fol lowed by d is p os al. Japane s e P at ent No.  911057 0 A2d escribe s the tre atment of  s ewag e slu dge with a n acidic  solution follo w ed  by d ryi ng tore duc e amm onia e v olu tionand to  r etainthe e ff ective n itrogen. Therein is des cribed  theuse  of dilut e ( 0 .3Normal) a queo us solutio nsofHCl,H2S O 4, an d wo o dvin e gar a s am m onia bind e rs  (“ G r an ulation ofC o m pos t Fro m S e wage S ludg e. V. Reduction o f  Ammonia Emiss ionF r omDry i ng P ro cess”, Hokkaid ori ts u Kogyo Sh ik enjo Hokoku , 287, 8 5- 8 9 (19 88)).None o f these r ef e rences  dis clo se the us e o fa cids wi th  a m monium  sul fa te add itions andn e ither referencediscu s s es th e  is sue o fcorrosi o n of  steel pro cess equipm ent un deracidconditi on s.
Ove r t he  past thir t y years a lkali ne stab il izat ion  of sl udge s has b eenasta ndard and s uc c es sf u l m etho d ofma king  sludgesi nto bene fic i ally us ef ulm a terial s  t h a t can be u sed  prin c i pally as s o il-c o nd i tioni ng mat erials . Becau s e t he se slud ges 
 content:_but are_unsuitable for combining with_sludge.
Another possible_candidate_that has_been_unsuccessfully tested by_the industry as_an additive to sludge_is ammonium sulfate._Although_ammonium sulfate has lower nitrogen content (21 wt % N) than the materials discussed_above,_it has_a_price_per unit of nitrogen comparable_to that of the other_commercial fertilizers._It is also relatively inert to the microbes_and_enzymes in sludge.
It_has been found in full-scale plant trials that a_problem occurs during the drying of_a mixture of_ammonium_sulfate_and sludge. Title 40_of the Code of Federal Regulations,_Part 503, Appendix B specifies that_the temperature of the sewage sludge particles_must exceed 80° C. (176° F.)_or the wet bulb temperature_of the_gas in contact with the_sewage sludge must_leave the_dryer at a_temperature exceeding 80° C. (176° F.)._However, when drying_a mixture of ammonium sulfate and_sludge,_a sudden release_of_ammonia_vapors occurs_at about 60°_C._(140° F.)_overwhelming_the air pollution control system. Several_attempts_at addition of ammonium sulfate to sewage_sludge in several different_plants_over several years have_foundered on this problem. The_discharge of ammonia to the atmosphere_is environmentally_intolerable. Consequently,_ammonium sulfate addition to sewage sludge has not been successful to_date.
European Patent No. 0143392 B1 describes_a process in which_an undigested_liquid_sludge is mixed_with_salts such_as ammonium sulfate at a concentration of_17-47 wt._% at a pH of 2-6_for a period of_3_to 12 hours followed by disposal._Japanese Patent No. 9110570 A2 describes_the treatment of sewage sludge_with_an_acidic solution followed by drying_to reduce ammonia evolution and to_retain the effective_nitrogen. Therein is described the use of_dilute_(0.3 Normal) aqueous solutions of HCl,_H2SO4,_and wood vinegar as ammonia binders_(“Granulation_of_Compost From Sewage Sludge. V._Reduction of Ammonia Emission From Drying_Process”, Hokkaidoritsu Kogyo Shikenjo Hokoku, 287, 85-89 (1988)). None_of these references_disclose the use of acids_with_ammonium_sulfate additions and neither reference discusses the issue of corrosion_of steel_process equipment under_acid conditions.
Over the past thirty years alkaline stabilization of sludges_has been a standard and successful method_of making sludges into beneficially useful materials that can be used_principally as soil-conditioning materials. Because these sludges