Page 434 - Industrial Wastewater Treatment, Recycling and Reuse

406 Industrial Wastewater Treatment, Recycling, and Reuse

10.2.2 Treatment Cost for Various Technologies
All these latest and advanced technologies employed in domestic wastewa-
ter treatment are highly energy intensive due to the aeration demand for
organic oxidation. The operating cost of aeration systems ranges from Rs.
3
1to9/m , making them unviable options for future use. The treatment
cost to produce effluent of a quality better than the Indian standard for dis-
charge into water bodies (biological oxygen demand (BOD 5 )<30 mg/L,
SS<30 mg/L) is different for different technologies. The WSP technology
3
has the lowest treatment cost and treats sewage at a cost of Rs. 1/m .The
conventional ASP system has a moderate treatment cost and produces trea-
3
ted water at a cost of Rs. 3.5/m .The treatment costforan SBRsystemis
3
Rs. 5/m . Similarly, among treatment options that produce effluents of
recyclable quality (BOD 5 <5mg/L and SS<5 mg/L), ASP followed by
sand filtration and carbon filtration has the lowest treatment cost, i.e.,
3
Rs. 6.5/m while the MBR process generatestreated waterat acost of
3
Rs. 9/m . The SBR system, followed by sand filtration and carbon
3
filtration, produces treated water at a rate of Rs. 7.5/m .The operating
cost of a UASB-based domestic sewage treatment system is in the range
3
of Rs. 0.5–1/m . However, it is necessary to evaluate these on a case-
by-case basis depending on the specific situation before arriving at a
conclusion. The application of UASB technology is a good option for
reducing the operating costs and enhancing energy generation from waste-
water. However, there are multiple process and operational difficulties
associated with the UASB system. There is no single solution for complete
wastewater treatment and a downstream aeration system is required for
complete treatment. UASB plants installed under various government
schemes failed to deliver the desired discharge quality of effluent due to
frequent operational failures. These failures occur because of maintenance
of biomass in the reactors and frequent washouts. It is very important to
maintain proper hydraulic conditions within UASB reactors. Upflow
velocity and settling rates need to be balanced for efficient functioning
of the bioreactor. Anaerobic microbial species are very sensitive to organic
shock loads and temperature variations. In general, UASB technology
demands more highly skilled operators compared with other aerobic
wastewater treatment technologies.
Considering the above facts, water and energy nexus have become crit-
ical factors in developing efficient and sustainable technologies for sewage
treatment. A need exists to develop technologies that can provide recyclable
quality water with low-operating costs and a smaller footprint. The