Drinking Water Quality Assessment and Analysis of Centralized and Decentralized Wastewater Treatment Systems in the Philippines
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Date
2009-08-10
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Abstract
The Philippines is a nation in Southeast Asia seeking to move forward in its development. The centralized and decentralized water and sanitation industries are growing, and a nongovernmental organization, Gawad Kalinga (GK), has taken a leading role to address issues of homelessness and poverty, significant problems throughout the country. This project had two main goals: to assess the effectiveness and sustainability of water and sanitation systems installed in villages built by Gawad Kalinga to help ensure systems installed in future villages are reliable; and to assess the microbial populations in three of the wastewater treatment plants (WWTPs) operated in Metro Manila, with the goal of identifying organisms present in the treatment plants to allow for improved design and operation of future WWTPs.
Water quality was measured at 27 GK sites (from 43 sources) using Hach portable laboratory equipment and 3M coliform petri plates. The following parameters were measured: pathogens, total coliforms and thermotolerant bacteria (E. coli), acidity, alkalinity, arsenic, carbon dioxide, chloride, chlorine dioxide, free and total chlorine, color, total dissolved solids, copper, hardness, iron, manganese, nitrate, nitrite, ammonia, pH, dissolved oxygen, phosphate, sulfate, sulfide, suspended solids, temperature and turbidity.
Results show that 95% of the sites visited tested positive for pathogens, as indicated by the Hach PathoScreen test. Many wells (52%) tested positive for total coliforms. E. coli was found in several of the wells (16%), but was not found in any municipally provided water source. Nitrate levels above the WHO and Philippine national standard of 35 mg/L were found in 30% of sources measured, and arsenic levels at or above the WHO standard of 50 ppb was found in one site. Interviews with 154 beneficiaries indicated that GK was responsible for a net improvement in water availability and sanitation access for 28% of its residents after they moved to GK villages.
Three WWTPs were sampled for molecular analysis: University of the Philippines (UP), PhilAm, and Makati South. These three plants serve different communities and are designed slightly differently. Terminal restriction fragment length polymorphism (T-RFLP) was performed on samples taken from each of the plants in February, 2008 and again in March (UP) or June (PhilAm, Makati South) to determine changes in the microbial communities over time. Results indicate that though there was a change over time (most significantly for the UP treatment plant), most of the terminal restriction fragments do not match with known fragments, indicating most of the species in the samples are not in the T-RFLP database. Cloning results confirm the presence of potentially novel species, and approximately 64% of species cloned did not match 98% identity with known sequences. Results that were able to be matched with known species via phylogeny indicate that β-Proteobacteria comprise the largest fraction of microorganisms in the sampled WWTPs, followed by Firmicutes.
The Makati South WWTP had lowest levels of diversity and richness among the three plants, but Manila Water Services, Inc reports that Makati South is the most reliable WWTP among those sampled for effluent water quality.
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molecular methods, Philippines, Manila, WWTP, activated sludge, microbial community, Wastewater treatment, Water Quality, Septic Tanks, Developing Country, developing countries
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Degree
MS
Discipline
Civil Engineering
