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Web End = Environ Sci Pollut Res (2015) 22:1643416440 DOI 10.1007/s11356-015-5307-8
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Web End = REVIEW ARTICLE
An obstacle to Chinas WWTPs: the COD and BOD standards for discharge into municipal sewers
Zhenliang Liao1,2 & Tiantian Hu1 & Scott Albert C. Roker2
Received: 25 April 2015 /Accepted: 24 August 2015 /Published online: 5 September 2015 # Springer-Verlag Berlin Heidelberg 2015
Abstract In 2001, a construction campaign regarding waste-water treatment plants (WWTPs) occurred in China. Unfortunately, the treatment has not yet achieved anticipated effectiveness. A critical reason for this is that the influent chemical oxygen demand (COD) and biochemical oxygen demand (BOD) concentrations in WWTPs are unacceptably low. This paper indicates that a fundamental, but commonly overlooked contributing factor to this problem is that a large portion of easily degradable COD and BOD is degraded prematurely before entering municipal sewers, and this is directly correlated to Chinas standards for pollutant discharging into municipal sewers. This perspective is further unfolded through retrospection of the history of Chinese wastewater treatment and the investigation of standards among developed zones and districts. This paper suggests that in China, the standards for pollutant discharging into municipal sewers should be relaxed. Meanwhile, unnecessary pretreatment of COD and BOD should cease for the purpose of ensuring that easily degradable COD and BOD can be transferred to WWTPs to improve treatment efficiency. Moreover, additional alternatives are presented to resolve this problem.
Keywords Wastewater treatment plants . Influent concentrations . Discharge . Standards . Municipal sewers
Introduction
To remedy severe water pollution resulting primarily from substantial discharge of wastewater, China launched a construction campaign of wastewater treatment plants (WWTPs) in 2001, which is mainly based on biochemical processing. The number of WWTPs is increasing rapidly. The number was 315 in 2000 (Qiu et al. 2010b). However, this number rose to 3340 by 2012 (Jin et al. 2014). The Twelfth Five-Year Plan of Energy Conservation and Emission Reduction (2011 to 2015) of China indicates that the municipal wastewater treatment rate should reach 85 % at the end of 2015. Furthermore, sufficient reduction of nitrogen (N) and phosphorus (P) is required by...