Sanitary

SAINT LOUIS UNIVERSITY

SCHOOL OF ENGINEERING AND ARCHITECTURE

DEPARTMENT OF CIVIL ENGINEERING

CE 424

SANITARY ENGINEERING

BAGUIO SEWAGE TREATMENT PLANT

SUBMI TTE TTED BY: BALDE LDERAS, J OHN BENEDI CT B. B.

DATE: TE: 03- 19- 13

SUBMI TT TTED TO: EN ENGR. J . R R.. CR CRUZ

RATI NG NG:

HISTORY & BACKGROUND: Somet i mes i n 1970, t he Ci t y of Bagui o was sued by t he muni ci pal i t y of La Tr i ni dad, Benguet f or pol l ut i ng t he Bal i l i Ri ver . The Bal i l i Ri ver or i gi nat es f r om t he ci t y of pi nes and r uns down t o l a Tr i ni dad Val l ey. At t hat t i me al l sewage wat er comi ng f r om r esi dent i al houses ar e di r ect ed t o st r eams t hat ar e connect ed t o t he r i ver t her eby pol l ut i ng t he wat er t hat f l ows t hr ough i t causi ng t he i r e of t he near by muni ci pal i t y as t hey cannot any mor e use t he wat er even f or wat er i ng t hei r pl ant s. As a sol ut i on, i t was agr eed t hat t he ci t y of Bagui o wi l l const r uct a sewage t r eat ment pl ant so t hat t he sewage comi ng f r om r es i dent i al hous es wi l l be t r eat ed f i r s t bef or e bei ng r el eas ed t o t he Bal i l i Ri ver t o i mpr ove t he qual i t y of t he wat er and s o t hat i t c an s t i l l be ut i l i z ed t o wat er c r ops i n L a t r i ndad. The const r uct i on of a gr i t chamber & PST was st ar t ed i n 1975 and was compl et ed i n 1980 but l acked t he necess ar y f undi ng and has t o be st opped. At one t i me, t he mayor was abl e t o get a Gr ant t hr ough i t s si st er ci t y i n J apan; t he agr eement was f or t he J apanese count er par t t o desi gn and const r uct t he Sewage t r eat ment pl ant whi l e t he ci t y of Bagui o wi l l const r uct t he ci t y sewer l i nes t o whi ch sewage comi ng f r om houses i n di f f er ent bar angays wi l l be connect ed. I n 1982, engi neer s f r om  J apan came t o conduct a f easi bi l i t y st udy and at t he same t i me gat her al l i nf or mat i on needed f or t he desi gn of an STP and went

back t o J apan t o make t he desi gn. I n 1984 t he Pl ant const r uct i on was st ar t ed and was compl et ed and oper at i onal i n 1986. The cont r act or was Tobi shi ma whi l e t he super vi sor was LUWA. Today, we have an Act i vat ed Sl udge Pr ocess STP oper at i ng 24 hour s a day @ 8600 cu. m/ day capaci t y f or al r eady 27 year s.

SEWAGE PROCESS AND TREATMENT  Two t ypes of pr ocesses occur dur i ng t r eat ment as t he sewage passes t hr ough t he di f f er ent st ages i n t he pl ant : t he physi cal pr ocess and t he Bi ol ogi cal Pr ocess. The f ol l owi ng i s t he st ep by st ep pr ocess st ar t i ng f r om t he i nl et of sewage t o t he out l et of t r eat ed wat er and c ol l ec t e d f er t i l i z er s :

The Grit Chamber: Her e t he sewage passes t hr ough st eel

gr at es

t o screen t he l ar ge si zed wast e. Thi s pr ocess i s cal l ed scr eeni ng and i t i s a Physi cal pr ocess.

The preliminary Sedimentation Tank Sludge Collector. Her e

t he s et t l e abl e s l udge s et t l es and i s col l ect ed i n t he s l udge c ol l ec t o r ; t hi s s l udge i s t hen pumped t o t he f i nal sedi ment at i on t ank. The sewage wi t h t he unset l l eabl e sl udge pr oceeds t o t he oxi dat i on di t ch passi ng t hr ough t he aer at or s. Thi s i s a physi cal pr ocess.

 Aerators/Oxidation Ditch. Her e i s a Bi ol ogi cal pr ocess wher ei n

t he sewage i s aer at ed and t he mi cr oor gani sms r esi di ng i n i t wi l l eat t he non- s et t l eabl e s ol i ds t hat wi l l l at er on s et t l e wi t h t he bact er i a t hat has eat en enough sol i ds. The Bagui o Sewage t r eat ment pl ant has at l east ei ght aer at or s t hat ar e oper at i onal .

Final sedimentation sludge collector / Chlorinator/thickened sludge collector/ sludge storage mixer/ sludge drying bed. Her e

t he pr evi ousl y non set t l eabl e sol i ds whi ch was eat en by t he mi croor gani sms wi l l set t l e and ar e col l ect ed i n t he f i nal sedi ment at i on t ank. The t r eat ed wat er on t op pr oceeds t o t he Chl or i nat or and t hen r el eased t o t he Bal i l i Ri ver whi l e t he sl udge at t he bot t om pr oceeds t o t he sl udge t hi ckener , t hen t o t he sl udge st or age t ank mi xer and f i nal l y t o t he dr yi ng bed, her e t he sol i d sl udge l ooks l i ke soi l and can be used as f er t i l i zer s.

Conclusion and Observation: As was gat her ed dur i ng t he si t e vi si t , t he desi gn capaci t y of t he STP i s 8, 600 cu. m / day but t he act ual r ecei ved sewage per day i s 10, 250 cubi c met er , meani ng t he pl ant i s over i t s desi gn capaci t y. Of t he 127 bar angays i n Bagui o ci t y, onl y 60 bar anggays ar e par t i al l y connect ed t o t he sewer s. Si nce gr avi t y i s used t o t r anspor t sewage t hr ough t he sewer s, onl y t hose houses t hat has sewage out l et hi gher t han t he sewer ar e abl e t o connect . Ther e i s, however , a const ant i ncr ease i n t he act ual sewage bei ng pr ocess ed i n t he pl ant because ot her new connect i ons ar e bei ng made i n t i me. Wi t h t he si t uat i on j ust st at ed, and consi der i ng t hat t he STP i s al r eady over l oad wi t hout cover i ng even hal f of Bagui o, we can concl ude t hat t he Bagui o sewage pl ant i s not enough and al r eady i nadequat e. The or i gi nal pur pose of mi ni mi z i ng t he pol l ut i on i n t he Bal i l i Ri ver i s no l onger al so a good obj ect i ve i f we have t o make t he ci t y of Bagui o cl ean and gr een. One obser vat i on al so i s t hat t he ar ea wher e t he Sewage t r eat ment pl ant i s l ocat ed i s al r eady cr owded wi t h r esi dent i al houses and t he smel l of t he sewage can be smel l ed even at a di st ance. The sewage i n t he oxi dat i on

di t ch i s exposed t o open ai r and a good amount of unt r eat ed sewage evapor at es al so pol l ut i ng t he ai r i n t hat ar ea. Wi t h t hi s obser vat i on agai n, even t he l ocat i on of t he sewage t r eat ment pl ant i s not any mor e a good l ocat i on unl ess addi t i onal measur es ar e done t o t r eat t he odor ous ai r evapor at i ng f r om i t .

Recommendation: A pr oposal may be t o moder ni ze t he pr esent STP whi ch i s, accor di ng t o t he engi neer i n char ge, convent i onal and ol d met hod of pr ocessi ng sewage. Cur r ent l y, t he pl ant occupi es one hect ar e of l and i n or der t o oper at e. A Sequential Batch Reactor or (SBR) can pr ocess 10, 000 cu. m/ day

of sewage and r equi r es onl y 400 sq. m of l and t o be oper at i onal ; meani ng at l east 20 of t hi s ki nd can be i nst al l ed i n a one hect ar e ar ea and can pr ocess 200, t housand cubi c met er of sewage day. I f t hese f aci l i t i es can be put up i n st r at egi c pl aces i n Bagui o, t hen per haps i t can sol ve t he pr obl em of sewage pol l ut i on i n t he ci t y. A t hor ough f easi bi l i t y st udy, however , i s needed i n or der t o come up wi t h such pr oposal . Anot her r ecommendat i on i s t o do somet hi ng on t he bad smel l emanat i ng f r om t he STP.  Though no peopl e ar e compl ai ni ng, i t wi l l not t ake a

geni us t o know t hat i n one way or anot her , t hi s af f ect s t he heal t h of t he peopl e r esi di ng ar ound i t .