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Jamwal, Priyanka
- Contribution of Sewage Treatment to Pollution Abatement of Urban Streams
Abstract Views :235 |
PDF Views:111
Authors
Affiliations
1 Centre for Environment and Development, Ashoka Trust for Research in Ecology and the Environment, Jakkur, Bengaluru 560 064, IN
1 Centre for Environment and Development, Ashoka Trust for Research in Ecology and the Environment, Jakkur, Bengaluru 560 064, IN
Source
Current Science, Vol 108, No 4 (2015), Pagination: 677-685Abstract
In this study, we assessed the efficiency and effectiveness of the Vrishabhavathy Valley Treatment plant (VVTP) in Bengaluru city, which is the oldest STP in the city. Since VVTP treats both raw sewage and polluted river water, with the latter constituting 80% of the influent, we sampled water quality at locations upstream and downstream of the plant to evaluate overall efficacy as well.
We found that VVTP is able to reduce biochemical oxygen demand (BOD5) by only 47%. This low efficiency can be attributed to the high and variable levels of chemical oxygen demand, consistent with episodic industrial discharges. Moreover, the mean values of pH, dissolved oxygen, total suspended solids, BOD5, nitrates, faecal coliforms and faecal streptococcus did not change significantly between upstream and downstream locations.
Treating river water using an STP is clearly not an efficacious way of improving river water quality. Thus, before setting up new STPs, sewerage boards need to invest in building the underground drainage network to bring raw sewage to existing STPs.
Keywords
Biochemical Oxygen Demand, Particulate Re-Suspension, Wastewater Treatment, Urban Stream, Water Quality.Full Text
- Effect of Flow Velocity on Chlorine Decay in Water Distribution Network:A Pilot Loop Study
Abstract Views :224 |
PDF Views:89
Authors
Affiliations
1 Centre for Environment and Development, Ashoka Trust for Research in Ecology and the Environment, Jakkur, Bengaluru 560 064, IN
2 Department of Civil Engineering, Indian Institute of Science, Bengaluru 560 012, IN
1 Centre for Environment and Development, Ashoka Trust for Research in Ecology and the Environment, Jakkur, Bengaluru 560 064, IN
2 Department of Civil Engineering, Indian Institute of Science, Bengaluru 560 012, IN
Source
Current Science, Vol 111, No 8 (2016), Pagination: 1349-1354Abstract
Experiments were run in the pipe loop setup to estimate bulk and wall chlorine decay rates under varying flow and chlorine levels for groundwater. A recirculating loop of 50 mm inner diameter polyvinyl chloride pipe and a variable flow pump with feed and recirculation tank were used to design a pipe loop. Sodium hypochlorite was introduced as free chlorine into the test water. The study came up with three important findings: (a) bulk chlorine decay rate in test water decreased with increase in chlorine levels, which is attributed to the type and level of organic matter present in test water. (b) Chlorine decay rate in pilot loop setup increased with increase in flow velocity. The result showed that under turbulent conditions, in addition to chlorine, mass flux transfer from bulk to wall and biofilm removal from pipe surface contributed to chlorine decay. We also noted that with increase in flow velocity the contribution of bulk reaction to total chlorine decay in pipe loop decreased. (c) ANOVA test on experimental dataset showed that as compared to initial chlorine levels, flow velocity has statistically significant effect on chlorine dissipation in a pipe loop. We also found that after turbulent flow is achieved, the effect of flow velocity on the wall decay is negligible.Keywords
Chlorine Decay, Pipe Loop Setup, Reynolds Number, Water Distribution Systems.Full Text
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