DOI: 10.5176/2251-189X_SEES16.8

Authors: Kanha But, Ranjna Jindal, Nawatch Surinkul and KimN.Irvine

Abstract: This research aimed at investigating the effluent quality and evaluate the current efficiency of the wastewater treatment system that receives and treats municipal wastewater and runoff from the seaside resort town of Cha-Am, Thailand. The treatment system for Cha-Am consists of four ponds constructed in sequence: i) aeration pond (AP); ii) sedimentation pond (SP); iii) extended aeration pond (EAP); and iv) evaporation pond (EP). Effluent discharges into a canal around the treatment plant for additional evaporation, but some of the effluent also discharges to the sea along the Cha-Am beach. Water grab samples were collected at six locations in the treatment system: influent chamber (IC), inlet and outlet of the aeration pond, and outlets of the sedimentation pond, extended aeration pond, and finally evaporation pond during June to September 2015. The target pollutants investigated in the grab samples included: total suspended solids (TSS), volatile suspended solids (VSS), chemical oxygen demand (COD), Total Kjeldahl Nitrogen (TKN), and Escherichia coli (E.coli). Two YSI 6920 datasondes were installed for the continuous monitoring (recorded at 30-minute intervals) of dissolved oxygen (DO), turbidity, conductivity, temperature, and pH, at the inlet of the aeration pond and outlet of the sedimentation pond. The overall average pollutant reductions were found to be in the range of 24.64{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465}, 47.96{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465}, 18.95{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465}, 83.18{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465}, and 99.99{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} for TSS, VSS, COD, TKN, and E.coli, respectively. The treatment system appeared to be good for removing TKN and E.coli. However, the removal efficiency for TSS, VSS, and COD is low. The overall average values of the data recorded by YSIs over a period of 85 days for temperature, conductivity, DO, pH and turbidity were 31.10 oC, 4.34 mS/Cm, 3.09 mg/L, 7.44, and 70.57 NTU, respectively at AP, and 30.82 oC, 4.56 mS/Cm, 3.30 mg/L, 8.39, and 71.20 NTU, respectively at SP. Temperature and DO decreased from inlet of AP to outlet of SP. pH at the outlet of SP was higher than inlet of AP and conductivity and turbidity were almost similar in each pond. Improvement of removal efficiency could be undertaken by some measures such as, longer aeration period and shallower depth of AP to enhance dissolved oxygen concentration; increased hydraulic retention time in SP to allow substantial settling of suspended matter, etc.

Keywords: Wastewater treatment ponds, dissolved oxygen, pollutants, total suspended solids, volatile suspended solids, Total Kjeldahl Nitrogen, Escherichia coli.


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