Subspaces And Spans

yet lo be detennined and communication bet,,·een upper and lo,,er aquifers has ^)Cl to be investigated (Fox • 1989).

7. Introduce piped ,,·ater from surface ,vatcr supplies far removed from threats 10 water-borne diseases. This ,viii require large infrastructure and the possibility of contamination along the line of distribution cannot be complete!) eliminated. In addition to lhis the technolog) is costl) and requires technical expenise. It is

unlike\) to be applicable in rural areas ,vhere the problem 1s more.

There arc ho,,cver some issues of consideration ,vhen it comes to mitigating lhe impacts of As pollution ,vorld" idc. The issues ¹⁰ one ,,a> or the: other hru; the potential of limiting the success of cffons din:ctcd to,�ards this direction The) are (\VI 10. 2000)·

a. there are no pro,co technologies for the rcmovnl of As at \\ater collection points such as "'ells, hand pumps nnd �prings:

b. nc\\ types of ucatmcnt technologies including co-precipitation, ion exchange and nctivutcd alumina fihrntion arc just being field tested,

c. simple tcchnologu:s for hou">ehold ren1ovnl of As from ,,utcr arc fe" nnd ha\.c to be adopted to nnd pro, en sustuinnble in each d11tcrcnt scu111g, nnd

d some studies hll\ c Just reponcd pn:lim1nary succcs">l!s in using pacl..cts of chemicals for household in:a1men1. Some mixtures eo1nbined ,\s rcmo, ol \\'1th

disinfccuons c g the \\'ltO PAI 10 ond Centre for Sanitary Engineering und Environmental Se1ences 10 Limn. Peru (CEPIS) Rut this hus 1101 been \\11.lcl ⁾ 1mplementcd

Vanous inno,11tl\e trc:itmcnt methods rcco1111nc111Jcd for the rcn1ovol or urscn,c 1n dnnk ⁱ ng ,.,.a,er ,nelude (iullsoy1o.nn1s nnd Zouboulb, 2002, Patrusc,$1.:) ct ol, �OOR) (o) udsorpu,c fihro1ton, using iron oxide: contcd sonJ or polymeric motc:nnls,

lb) 1ero-\.alen1 iron.

(c) solur dts ⁱ nlcc11on, solor ox1dallon nnd remo,ill of rscn1c (SOR/\�).

(d) iron,baseJ odsorbcnts. such 115 gronulnr lcmc h)droxlde {GI H),

(c) b ⁱ ological ox ⁱ d:111on and n:mo,nl of oBCn1e occomphmc:d 1n1uhoneou I ⁾ wuh 1h�

biological ⁱ ron ox1dn1ton (b1orcmcd1n11on) In tuld111on, other ,norc t<1n, cnuonal nic:tho<ls for nrscn ⁱ c rcmo, I urc olS<l n, 1l11blc uch ns Iron or nlum con •ulounn hni

UNIVERSITY OF

IBADAN LIBRARY

AFRICAN DIGITAL HEALTH REPOSITORY PROJECT

soltenin�. ion exchange, activated nlumiru, nnd memb ^ra ne scpamtion processes. Dcu1ils of these n,cthods have been extensively dcscribc<l by, ,\hholT and Bnucl (.2002); Zu,,

nnd Enunct, (2002); Yuan, l.uo, I lu Ong and Ng (2003); Kutsoyinnnis and Zouboulis (2002: 2004; 2006): l.cupin nnd Jiog; (2005) and Kat.so) innnis , Zouboulis ,

Patruscvl\ky ct nl (2008).

I he uforcn,cnhoncd methods hn\'c been con,para1ivel) c,•nluatcd nnJ the relevant conclus,ons hove been dru\\ n \\ilh respect to the upplic�bility of arsenic lrcatn,cnl nicthods, depending on certain parameters, such as locally varying \\Ul�·r quality choructeristics, sus111innbilily, und economic lcnsibility (Kntsoyi,mnis and

Zouboulis, 2006).

2. 20. l-louschold Mitigation �lcnsurc,

The proble1ns posed by As dcn1nntl thnt n11t1g.,1ini;. 11ctions be initintcd 111 \11rious h:\lcls. These oct1ons us n ,natter of necessity n1us1 include sin1ple ,\s rcmovnl methods ,vhich ,viii be nvoilnble nt household levels. rhis is bccnusc ,\s pose· problen1 spccilicnlly nt household level .u1d the de, elop,ncnt or nhcmoti ^\' c \\'Oler supphe� <1nd the ,n�tallnlion of larger ,\s rcmovol units mny not be feasible nt nll tin1cs und their

usefulness mny not be npplicoble to local situauons.

,\ number ol smoll-sculc ,\s rcmo,nl procedures \\hich h11,·e been cn1ployed in some places require chcn1icols thot arc either 1101 easily nvoilablc nnd/or olTcct \VDter tos1c and odour (�1uchtcr, L,cbl, Rcichl llunder, \Vuther and Ficht! 1997: ,\bb _io Kell), ui,,rie and Riggs, 2002; Potruscvsky ct nl. 2008) thus reducing the aesthetic volue of such

"·utcrs

SORAS (Solar Oxidution und Removal of Arsenic) is ¹¹ n11ithod 1h01 uses irrndinlion of ,vnter \\ith sunlight in PET�or other UV-1\ lnlnspM:nt bottles 10 reduce ,\s levels in dnnk1ng ,vuter The: method is based on photochcn11cut ox1do1ion of -\S(IJf)

tollo\,cd by prci;;ipitot1on ur fillf'lllion of As(\') adsorbed on Fe(lll) oxides SOR,\S could reduce As contents and ,vould be u \\'Utcr 1rea1mcn1 method u�d 111 household

level to treat small qunn11t1c::. of dnnking \\'Oler (K.itsoyiJnnis and Zouboulis ^2006).

17 UNIVERSITY OF

IBADAN LIBRARY

AFRICAN DIGITAL HEALTH REPOSITORY PROJECT

S()ARS removes ,\s in a 1wo-s1cp procedure Firstl). ,\s(l11) \\hich onh ,,e:ikl�

ndsorbs to 1 1 c (h)dr)oxidcs is oxidized to the strongly adsorbing ,\s(\ I S<.-condl�.

l·c(lll)(hydr)oxides formed fron, naturall) present iron are nllo,,cd to sctllc to the 00110n, of the contnincr ,vith lhc udsorhcd As(V) nnd the clcur \\'!Jtcr 1s Jcc.1ntcd (Fi�.

2.ll). ln\tc,td of udding chcn1ical oxidants such us chlorine or pcm1angun:11c, n:Jcti\'c oxidants ore produced photo-chemically ,v1th sunlight.

Rcscurch is ndvnncing on ho,v lo enhance ,\s(III) photo-oxidntion nt higher p�I by the tu.ldition of S{IV). In the presence of cllrote, the rcmo,nJ of,\� hus been found to be

much rn.�tcr.

Kl

UNIVERSITY OF

IBADAN LIBRARY

AFRICAN DIGITAL HEALTH REPOSITORY PROJECT

Fig. 2.8: Simple household filtration method to remove arsenic in B ^an gladesh

89 UNIVERSITY OF

IBADAN LIBRARY

Closed PI:.! bottles (fiRurcs. 2.9 _und 2.10) _h.1vc b<. "C n said 10 M\c SC\cml ndvantages O\cr open containers in that it docs not allo\\' lor contnminntion b) nirbomc pathogens, there is n1inimul loss of CO2 (,vh ¹ ch le-Jds to an increase of the pf[ ,11luc,

precipitation of iron(hydr)oxides und decantntion of the supcmu1,1nt \\iltcr is casil}

possible 1n vcnic.11ly placed bottle� PET bot1lcs urc locnll) n,·uilnblc nnd rcus.1blc for several 1non1h• (Kot,oyiunnis and Zouboulis 2006),

Other Po1nl of Use (POU) tcchnologic.s urc being c,perimcntcd in Cnlilomi11 (Fig. _2.11), llnnglndcsh nnd 01l1cr plnccs (llard,,ick. 2005). For inst.1nc, Keeler C SD introduced an nbsorplion technology cnllcd MEi's lsolux Tcchnoloro \\t.act. _ha., been

found very cllccllvc ¹ n rnnny ho,ncs. The systcn1 hus also been found to be cost ctlccuvc nnd nflordnblc cornparcd ,vith other technologies ,\ith and installotton cost of

about S300 (Hnr<hvick, 2005).

2. 21. Trcnhncnt tcchnoloAic�

/\ ,-.ido mngc of n1cthods hove been cmplo}cd in lhc 1rca11ncn1 of ,\s in many parts or the -.vorld. 111esc methods include·

o. ExCO\':tlion. TI1is is current!)' o \\idcly us'--d remedy for arscnic-contaminoted soils. This involved lhc rcn1ovol of soil from conuuninoted site to eliminate the po1en1inl ror lcaclnng to ground,,'llh:r. The soil is subse,1ucn1ly lnnd filled or treated ex- situ,

b. Copping: This technique utililcs an impcrmcnble surrucc barrier tho, reduces infiltmuon by pn:cipitntion or storm ,voter collected ,ll lhc lnnd's surface. Cops nrc designed 10 redirect m1nfnll to areas not conto1111n111cd nnd

or clin1inutc infiltration

C Soll SnlhJllic111ion/St11hlll,u1ion (SS) ^{SS is} ^kno,\·11 ^1L� chemical lixotion or cncap�ulauon anJ 1s extensively used 10 treat ,vr1Slc strcnms including

gruund,vatcr in·s11u or conwminu,ed •,oil� fhc moi,t con1111unly used method

utilizes cement or po12olun1c binder 10 reduce the toxicity und lenchabili1y of

In document Linear Algebra, Theory And Applications (Page 56-61)

yet lo be detennined and communication bet,,·een upper and lo,,er aquifers has )Cl to be investigated (Fox • 1989).

unlike\) to be applicable in rural areas ,vhere the problem 1s more.

There arc ho,,cver some issues of consideration ,vhen it comes to mitigating lhe impacts of As pollution ,vorld" idc. The issues 10 one ,,a> or the: other hru; the potential of limiting the success of cffons din:ctcd to,�ards this direction The) are (\VI 10. 2000)·

a. there are no pro,co technologies for the rcmovnl of As at \\ater collection points such as "'ells, hand pumps nnd �prings:

b. nc\\ types of ucatmcnt technologies including co-precipitation, ion exchange and nctivutcd alumina fihrntion arc just being field tested,

c. simple tcchnologu:s for hou">ehold ren1ovnl of As from ,,utcr arc fe" nnd ha\.c to be adopted to nnd pro, en sustuinnble in each d11tcrcnt scu111g, nnd

d some studies hll\ c Just reponcd pn:lim1nary succcs">l!s in using pacl..cts of chemicals for household in:a1men1. Some mixtures eo1nbined ,\s rcmo, ol \\'1th

disinfccuons c g the \\'ltO PAI 10 ond Centre for Sanitary Engineering und Environmental Se1ences 10 Limn. Peru (CEPIS) Rut this hus 1101 been \\11.lcl ) 1mplementcd

Vanous inno,11tl\e trc:itmcnt methods rcco1111nc111Jcd for the rcn1ovol or urscn,c 1n dnnk i ng ,.,.a,er ,nelude (iullsoy1o.nn1s nnd Zouboulb, 2002, Patrusc,$1.:) ct ol, �OOR) (o) udsorpu,c fihro1ton, using iron oxide: contcd sonJ or polymeric motc:nnls,

lb) 1ero-\.alen1 iron.

(c) solur dts i nlcc11on, solor ox1dallon nnd remo,ill of rscn1c (SOR/\�).

(d) iron,baseJ odsorbcnts. such 115 gronulnr lcmc h)droxlde {GI H),

(c) b i ological ox i d:111on and n:mo,nl of oBCn1e occomphmc:d 1n1uhoneou I ) wuh 1h�

biological i ron ox1dn1ton (b1orcmcd1n11on) In tuld111on, other ,norc t<1n, cnuonal nic:tho<ls for nrscn i c rcmo, I urc olS<l n, 1l11blc uch ns Iron or nlum con •ulounn hni

UNIVERSITY OF

IBADAN LIBRARY

soltenin�. ion exchange, activated nlumiru, nnd memb ra ne scpamtion processes. Dcu1ils of these n,cthods have been extensively dcscribc<l by, ,\hholT and Bnucl (.2002); Zu,,

nnd Enunct, (2002); Yuan, l.uo, I lu Ong and Ng (2003); Kutsoyinnnis and Zouboulis (2002: 2004; 2006): l.cupin nnd Jiog; (2005) and Kat.so) innnis , Zouboulis ,

Patruscvl\ky ct nl (2008).

Zouboulis, 2006).

2. 20. l-louschold Mitigation �lcnsurc,

usefulness mny not be npplicoble to local situauons.

"·utcrs

SORAS (Solar Oxidution und Removal of Arsenic) is 11 n11ithod 1h01 uses irrndinlion of ,vnter \\ith sunlight in PET�or other UV-1\ lnlnspM:nt bottles 10 reduce ,\s levels in dnnk1ng ,vuter The: method is based on photochcn11cut ox1do1ion of -\S(IJf)

tollo\,cd by prci;;ipitot1on ur fillf'lllion of As(\') adsorbed on Fe(lll) oxides SOR,\S could reduce As contents and ,vould be u \\'Utcr 1rea1mcn1 method u�d 111 household

level to treat small qunn11t1c::. of dnnking \\'Oler (K.itsoyiJnnis and Zouboulis 2006).

17

UNIVERSITY OF

IBADAN LIBRARY

S()ARS removes ,\s in a 1wo-s1cp procedure Firstl). ,\s(l11) \\hich onh ,,e:ikl�

ndsorbs to 1 1 c (h)dr)oxidcs is oxidized to the strongly adsorbing ,\s(\ I S<.-condl�.

l·c(lll)(hydr)oxides formed fron, naturall) present iron are nllo,,cd to sctllc to the 00110n, of the contnincr ,vith lhc udsorhcd As(V) nnd the clcur \\'!Jtcr 1s Jcc.1ntcd (Fi�.

2.ll). ln\tc,td of udding chcn1ical oxidants such us chlorine or pcm1angun:11c, n:Jcti\'c oxidants ore produced photo-chemically ,v1th sunlight.

Rcscurch is ndvnncing on ho,v lo enhance ,\s(III) photo-oxidntion nt higher p�I by the tu.ldition of S{IV). In the presence of cllrote, the rcmo,nJ of,\� hus been found to be

much rn.�tcr.

Kl

UNIVERSITY OF

IBADAN LIBRARY

Fig. 2.8: Simple household filtration method to remove arsenic in B an gladesh

89

UNIVERSITY OF

IBADAN LIBRARY

Closed PI:.! bottles (fiRurcs. 2.9 und 2.10) h.1vc b<. "C n said 10 M\c SC\cml ndvantages O\cr open containers in that it docs not allo\\' lor contnminntion b) nirbomc pathogens, there is n1inimul loss of CO2 (,vh 1 ch le-Jds to an increase of the pf[ ,11luc,

precipitation of iron(hydr)oxides und decantntion of the supcmu1,1nt \\iltcr is casil}

possible 1n vcnic.11ly placed bottle� PET bot1lcs urc locnll) n,·uilnblc nnd rcus.1blc for several 1non1h• (Kot,oyiunnis and Zouboulis 2006),

Other Po1nl of Use (POU) tcchnologic.s urc being c,perimcntcd in Cnlilomi11 (Fig. 2.11), llnnglndcsh nnd 01l1cr plnccs (llard,,ick. 2005). For inst.1nc, Keeler C SD introduced an nbsorplion technology cnllcd MEi's lsolux Tcchnoloro \\t.act. ha., been

found very cllccllvc 1 n rnnny ho,ncs. The systcn1 hus also been found to be cost ctlccuvc nnd nflordnblc cornparcd ,vith other technologies ,\ith and installotton cost of

about S300 (Hnr<hvick, 2005).

2. 21. Trcnhncnt tcchnoloAic�

/\ ,-.ido mngc of n1cthods hove been cmplo}cd in lhc 1rca11ncn1 of ,\s in many parts or the -.vorld. 111esc methods include·

o. ExCO\':tlion. TI1is is current!)' o \\idcly us'--d remedy for arscnic-contaminoted soils. This involved lhc rcn1ovol of soil from conuuninoted site to eliminate the po1en1inl ror lcaclnng to ground,,'llh:r. The soil is subse,1ucn1ly lnnd filled or treated ex- situ,

b. Copping: This technique utililcs an impcrmcnble surrucc barrier tho, reduces infiltmuon by pn:cipitntion or storm ,voter collected ,ll lhc lnnd's surface. Cops nrc designed 10 redirect m1nfnll to areas not conto1111n111cd nnd

or clin1inutc infiltration

C Soll SnlhJllic111ion/St11hlll,u1ion (SS) SS is kno,\·11 1L� chemical lixotion or cncap�ulauon anJ 1s extensively used 10 treat ,vr1Slc strcnms including

gruund,vatcr in·s11u or conwminu,ed •,oil� fhc moi,t con1111unly used method

utilizes cement or po12olun1c binder 10 reduce the toxicity und lenchabili1y of

yet lo be detennined and communication bet,,·een upper and lo,,er aquifers has ^)Cl to be investigated (Fox • 1989).

There arc ho,,cver some issues of consideration ,vhen it comes to mitigating lhe impacts of As pollution ,vorld" idc. The issues ¹⁰ one ,,a> or the: other hru; the potential of limiting the success of cffons din:ctcd to,�ards this direction The) are (\VI 10. 2000)·

disinfccuons c g the \\'ltO PAI 10 ond Centre for Sanitary Engineering und Environmental Se1ences 10 Limn. Peru (CEPIS) Rut this hus 1101 been \\11.lcl ⁾ 1mplementcd

Vanous inno,11tl\e trc:itmcnt methods rcco1111nc111Jcd for the rcn1ovol or urscn,c 1n dnnk ⁱ ng ,.,.a,er ,nelude (iullsoy1o.nn1s nnd Zouboulb, 2002, Patrusc,$1.:) ct ol, �OOR) (o) udsorpu,c fihro1ton, using iron oxide: contcd sonJ or polymeric motc:nnls,

(c) solur dts ⁱ nlcc11on, solor ox1dallon nnd remo,ill of rscn1c (SOR/\�).

(c) b ⁱ ological ox ⁱ d:111on and n:mo,nl of oBCn1e occomphmc:d 1n1uhoneou I ⁾ wuh 1h�

biological ⁱ ron ox1dn1ton (b1orcmcd1n11on) In tuld111on, other ,norc t<1n, cnuonal nic:tho<ls for nrscn ⁱ c rcmo, I urc olS<l n, 1l11blc uch ns Iron or nlum con •ulounn hni

soltenin�. ion exchange, activated nlumiru, nnd memb ^ra ne scpamtion processes. Dcu1ils of these n,cthods have been extensively dcscribc<l by, ,\hholT and Bnucl (.2002); Zu,,

SORAS (Solar Oxidution und Removal of Arsenic) is ¹¹ n11ithod 1h01 uses irrndinlion of ,vnter \\ith sunlight in PET�or other UV-1\ lnlnspM:nt bottles 10 reduce ,\s levels in dnnk1ng ,vuter The: method is based on photochcn11cut ox1do1ion of -\S(IJf)

level to treat small qunn11t1c::. of dnnking \\'Oler (K.itsoyiJnnis and Zouboulis ^2006).

Fig. 2.8: Simple household filtration method to remove arsenic in B ^an gladesh

Closed PI:.! bottles (fiRurcs. 2.9 _und 2.10) _h.1vc b<. "C n said 10 M\c SC\cml ndvantages O\cr open containers in that it docs not allo\\' lor contnminntion b) nirbomc pathogens, there is n1inimul loss of CO2 (,vh ¹ ch le-Jds to an increase of the pf[ ,11luc,

Other Po1nl of Use (POU) tcchnologic.s urc being c,perimcntcd in Cnlilomi11 (Fig. _2.11), llnnglndcsh nnd 01l1cr plnccs (llard,,ick. 2005). For inst.1nc, Keeler C SD introduced an nbsorplion technology cnllcd MEi's lsolux Tcchnoloro \\t.act. _ha., been

found very cllccllvc ¹ n rnnny ho,ncs. The systcn1 hus also been found to be cost ctlccuvc nnd nflordnblc cornparcd ,vith other technologies ,\ith and installotton cost of

C Soll SnlhJllic111ion/St11hlll,u1ion (SS) ^{SS is} ^kno,\·11 ^1L� chemical lixotion or cncap�ulauon anJ 1s extensively used 10 treat ,vr1Slc strcnms including