Performance Evaluation of Central Wastewater Treatment Plant: a Case Study of Hetauda Industrial District, Nepal

Abstract

A central wastewater treatment plant (CWWTP) was established in Hetauda Industrial District (HID) to
treat industrial as well as sanitary wastewater. Brewery, dairy, vegetable ghee and soap factories are major
sources of high strength wastewater in HID. The main objective of this study was to evaluate the
performance of CWWTP in terms of BOD5, COD, TSS, TDS, oil and grease and ammonical nitrogen
removal. Moreover, the performance of the CWWTP related to pretreatment of wastewater in those
industries, so performances of pretreatment were also included in this study. Samples of wastewater were
collected from the CWWTP and from brewery, dairy, and soap factories for characteristic analysis. The
secondary data of influent and effluent monitoring of the CWWTP and pretreated wastewater of vegetable
ghee factory was also used. This study revealed that average concentrations of BOD5, COD, TSS, TDS,
oil and grease, and ammonical nitrogen in the effluent of CWWTP were 252, 1,226, 595, 384, 6.2 and
36.16 mg/l, respectively, which did not meet the effluent standards for BOD5, COD and TSS. The
pretreatment of wastewater at brewery, dairy, vegetable ghee and soap factories were not sufficient to
meet the pretreatment criteria. To overcome inefficient treatment, more factory sewerage systems should
be connected to the CWWTP to solve the problem of under BOD loading in anaerobic pond.wastewater
should be treated to meet pretreatment criteria before discharging to the CWWTP.