1. Analyses of chemic,li composition. of raw sludge. precipitated with lime was collected from. 2. Encapsulation of heavy metal

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2 be llsed as Por1tland cement replacement n varoll~ ap~lcaton ncludng waste contanment. The st~dy on contanment of heavy metal sludge fro~ the ndustral Waste TreatmenL Centre Samaedarn n Portland cement mortar showed large decrease n melal lenchate [2]. Sllce large quantty of cement has to be use~, partal replacement of Portland cement wth flyash may re~ult n consderable savngs. n ths study. Mae- moh flyash wa~ used as a cement replacement ll contanng Samaedam heavy metal waste. Portlao~ cement-oyash-waste mx was prepared ~s mortar 111 vanous ratlos. The mxes we,re tested for compressve strength and ]ea~hate then the optmum mxes were delermnej:l. Flyash-lmc mx was also tred n the en'capsulaton of heavy metal sludge. The et1fcenccs of metal contanment by both types of encapsulaton were compared. SJGNFC~NCE OF THE RESEARCH The r~sllts of the study should provde a better understandng of effectveness of the method of dsposal of heavy metal l sludge by enq.psulaton n flyash-cemcnt and lme-f1yash mxtures. t also gves a prelmnary gu~dance on the proportons of the cementtous rnxtutcs for each level of contanment. ' MATERAL AND METHODS 1. Analyses of chemc,l composton of raw sludge The sample of heavy metal sludge precptated wth lme was collected from the ndustral Waste Treatment Centre Samaedal1l The sludge was analysed for water content, total solds. volatle and fxed solds by gravmetrc method. Another porton of the sample was dgested for heavy metal content analyses by atomc absorplon spectrophotometer [3]. 2. Encapsulaton of heavy metal sludge wth f1yash-portland cement Raw sludge was mxed wth tlyash and Portland cement at varous proportons. The mx was cast n 5.0x5.0x5.0 cm. cubes and 9X4X2 em. prsms. All the mxes were controhed to have 80% flow. 2.1 p:f:w cubes were te~ted for compressve strength at 3,7, and 7.8 days. 2.2 Raw sluetge and the p:f:w mxes wth strength averll ksc (stpulated by the Mnstry of ndustry for stablzed waste to be dumped at dump ste) was selected for leachate test usng acetc acd as leachalt n USEPA -Extracton procedure f~]' The p:f:w prsms were mmersed n acetc acd leachant for 90 days. The leachant was then fltered through membrane of 0.45m pore sze. The fltrate was adjusted to ph2 for further analyses of Cll, Zn and Cr content by Atomc Absorpton Spectrophotometer.

3. Encapsulaton of heavy metal sludge n me-fl)'3sh mxture Raw sludge wa~ mxcd wth tlyash and lme (:f:w mx) at varous proportons (0.1 :0.9, 0.2:0.8,...,0.9:0.1) and cast n prsms.

3 3. Encapsulaton of heavy metal sludge n me-fl)'3sh mxture Raw sludge wa~ mxcd wth tlyash and lme (:f:w mx) at varous proportons (0.1 :0.9, 0.2:0.8,...,0.9:0.1) and cast n prsms. Afer settng, the specmens were dcmouldcd and were further ncubated untl the age of 28 days. 3.1 Settng tme and the strength of l:f:w mxes were examned. 3.2 Acceptable :f:w mxes were tested for leachablty as p:f:w mx. Leachablty of each mx. was compared to that of raw sludge. Optmum rato was determned hom the compressve strength and leachablty. 4. Comparson of encapsulaton effectveness of p:f:w and :f:w mxes Encapsulaton effectveness was defned as the capacty of heavy metal leachate reducton relatve to weght of metal leachcd from raw sludge. Encapsulaton effectveness 100 x (Ws-Wm)/Ws RESULTS AND D.SCUSSON 1. Analyses ofchemcal composton of raw sludge Chemcal composlllons of heavy metal sludge sample from Samaedam, collected on July 30,1998, are shown n tables 1a and 1 b. The sludge held hgh water content of 71.1 % w (h norganc matters (fxed solds) as a major consttuent of 22.9% by w. of raw sludge. t was found to contan ron(fe) and chromum (Cr) as major components. 2. Encapsulaton of heavy metal sludge n flyash-portland cement 2.1 Compressve strength of waste encapsuated n flyash - Portland cement mxes. p:r:w morlar specmens of varous mxes were tested for <.;ornpressvc strength at 3, 7 and 28 days. Mac-moh flyash affected the development of compressve strength of Portland cement mortar to some extent. The?a-day compressve strength of Portland cement mortar decreased from 913 bc. to , 353 ksc. n the pj mxes of 1: :0.8, and 1:1.2 respectvely (fg. 1). Compressve strength development of Portland cement mortar was sgnfcantly affected by sludge (fgure 2). Wth no ccmenttous property, sludge acted a~ a fller n tbe mxes, reducng compressve strength to 45, 1 (" 10, and 7 ksc n the p:w mx.es of 1:0.5,1:1, 1:1.5, and 1::;> respectvely. When the 3 components were mxed, the 28-day compressve strength of the same p:w rato ncreased wth an ncrease n tlyash proporton (sec table 2). Ths resulted both from the sphercal shape of the flyash, thus rcductng the water/bnder rato and also from ls pozzolanc reacton from the cementtous propelty of the major components n t1yash. SO?> Al 2 0 3, and CaO. At the rato of p:f = 1: tar can contan 1.5 parts of sludge wth acceptable

Table 1a composton of sludge Table 1b heavy metal content of sludge Water content; Total solds Fxed solds Volatle solds! 71.1 28.9 22.9 5.9 Copper (ell) 811 Znc (Zn) 7,806 Chromum (Cr) 11.

4 Table 1a composton of sludge Table 1b heavy metal content of sludge Water content; Total solds Fxed solds Volatle solds! Copper (ell) 811 Znc (Zn) 7,806 Chromum (Cr) ron (Fe) 94,643 Manganese (Mn) 1,483 Lead (Pb) 622 Cadmum (Cd) u en ~ 1(fD ) c ~ (j) (1) :(X) > 'en en 0 ~ a. E 0 u Fg. 1 Effect 1f o 5 1) 15.J) 3) ~(days) f' :0:0 _1:0.4:0!, -+-1:0.8:0 l!~1:12: 1 Mae-moh f1yasb on compressl'e strength ofportland cement mortar po, ho 20 o :0:1 -'-1:0:2 o age (days) Fg.2 Effect or heavy metal sludge on compressve strength of Portland eemc/lt mortar

Table 2 Compressve strength of p:f:w mortar at 28 days *_tt;) :~:~11rj~~~f:!0~ ;'~~t1tf; '_~~~~~W,.~}}~~Jfjf;;.1 w 0 913 S21 392 353 w 0.5 45 57 81 80 w 1.0 16 15 24 22 w 1.5 10 13 17 13 w 2.

5 Table 2 Compressve strength of p:f:w mortar at 28 days *_tt;) :~:~11rj~~~f:!0~ ;'~~t1tf; '_~~~~~W,.~}}~~Jfjf;;.1 w S w w w w strength conformng to the Mnstry of ndustry's requrement for dsposal of soldfed waste. 2.2 Heavy metal contaluncnt of sludge encapsulated n f1yash- Portland cement mxes. Encapsulaton of sludge n cement mx at varous rato affected leachablty of metal (see table 3). Leachablty ncreases wth ncreasng n raw sludge content. whje ncreasng n flyash content wth the same waste rato tends to decrease lcachabty. 'Tle rato of p:f:w = 1:0.3:1 and 1:1.2:1 gave good results n contanng Cr, wth maxmum waste proporton and yeldng the leachate of Jess than 5 mg/l (confomlng to USEPA standard). The 2 mxes were then found to be optmum mxes when compressve su'ength was also taken nto consderaton. 3. Encapsulaton of heavy metal sludge n lme-flyash mxture 3.1 Settng tme and strength of sludge encapsulated n Lme-flyash mxes. Varous mxes of lme:flyash (0.1: :0.13,...0.9:0.1) requred dfferent tme to set. Settng tme vared from J1 days for the mxes of less lme content to 12 days for more lme mxes. After 28 days llcubaton, the mxes wth more than 0.7 parts of lme were degraded n water, whle the mxes wth parts of lme were easly fallen off when pressng wth hands. Tlms only the :f mxes of 0.1 :0.9, 0.2:0.8. and 0.3:0.7 were used n further test. 3.2 Heavy metal contanment of sludge encapsulated n lme-fjyash mxes. Encapsulaton of sludge n U:w mxes decrease leachahlty of metal (table 4). Leachablty ncreased wth ncreasng: n raw sludge content. Decrease of f1yash content whle ncreasng of lme cuntent resulted n better conta lment. 'fhe l:f rato of 0.3:0.7 gave the least leachate among the tested mxes. However no mx of :f:w conformed to USEPA standard n contanng Cr (less than smg!1 leachate). 4. Comparson of contanment effectveness Both p:f:w and :f:w mxes reduced

Table 3 Leach/ltc from raw sludge and p:f:w mx (90 days n acetc acd C3chant ) ~~[at'jzlt(:j~~~~~;t:'~:~t~l'k~=], Cr 21.8J.183 w 0.5 ',.7625 L1.4597 2.7455 2.3126 w 1.0 (,.4251 5.8303 4.8986 3.

6 Table 3 Leach/ltc from raw sludge and p:f:w mx (90 days n acetc acd C3chant ) ~~[at'jzlt(:j~~~~~;t:'~:~t~l'k~=], Cr 21.8J.183 w 0.5 ',.7625 L w 1.0 (, w w ~) Zn w w 1.0 ~ w v.,.' J Cu _. w w J w 1,..J w ~P-"";~ Table 4 Leachrtc from raw sludge and :f:w mx (90 days n acetc acd leachant ) w w J V ,9714 w Zn w L Vo w W 2.0 H Cu w w SOLl9 OJ ~. w w

'JVU# 45 'th::~nd 2545 Table 5 Comparson of contanment percentage of optmum flyash mxes p:f:w 1:l.2:1 66.87 47.56 76.34 p:f:w 1:0.8:l 63.l9 62.58 74.77 l:f:w 0,2:0.8:1 35.29 28.73 42.55 l:f:w 0.3:0.

7 'JVU# 45 'th::~nd 2545 Table 5 Comparson of contanment percentage of optmum flyash mxes p:f:w 1:l.2: p:f:w 1:0.8:l 63.l l:f:w 0,2:0.8: l:f:w 0.3:0.7:l leachate from raw,sludge through encapsulaton (table 5). Portland cement-flyash mxes were marc effectve n contanng heavy metal sludge at the same proporton of f1yash:waste (0.8:1). However, l:f mx at 0.3:0./ also showed sgnfcant contanment capacty. CONC"USON Two factors nfluencng the choce of encapsulaton materals and proportons were addressed n ths study, frstly, the materals must yeld strong enough mxes to wthstand handlng durng dsposal Secondly, the resultng matrx must encapsulate the waste suffcently well to prevent excessve leachate uoder dsposal condtons. ndvdually, Portland cement was the most potent materal, provdng both the strength and encapsulaton. For cost redw.:toll, nyash and lme were tred. Flyash was also effectve actng n tandem wth ether Ponland cement or wth lme. Whle flyash-cement was the more effectve of the two, flyashlme provded an attractve alternatve. REFERENCES [J Berry, E.E. and Malhotra, V.M. (1978). Fly ash for use n concrete. Part2: A crtcal revew of the effects of fly ash on the propertes of concrete. Energy, Mnes arld Resources. Canada,Ottawa, ON. CANMET report [2j Suwanvtaya, P. and Tuanpoosa, p. (l998). Hazardous waste stablzaton by cement. Engneerng Journal Kasetsart, v.33, pp [3J Amercan PubLc Health Assocaton (APHA), Standard Me/bod for the Examnaton of Water and Wastewater, '18th Edn, APHA, Washngton D.C., [l] US.Envronmental Protecton Agency. (1 ';/S). Ha7aTdous Waste ChaTacterstcs Federal Regsler, 43 (243).

Improvement on the properties of gypsum particleboard by adding cement*

Improvement on the properties of gypsum particleboard by adding cement* J Wood Sc (1998) 44:98-102 The Japan Wood Research Socety 1998 Yuhe Deng Takesh Furuno Tohru Uehara Improvement on the propertes of gypsum partcleboard by addng cement* Receved: February 26, 1997 / Accepted: