[Analysis of the secondary effluent of municipal wastewater in north China].
The secondary effluent from a municipal sewage treatment plant was fractionated into three parts: the dissolved, the near-colloidal and the suspended. The variation of each composition was investigated individually during winter, spring and summer. The fractionation study revealed that the dissolved COD and DOC accounted for 78.2%-86.5% of total COD and 82.6%-86.6% of TOC, respectively. The molecular weight distribution (MWD) of the secondary effluent indicated that the organics with molecular weight (MW) < 1000 accounted for 56.3%-62.8% of total organics. The organic components constituted 75.54%-89.93 % of the mixture of suspended and near-colloidal matter. The size distribution of the particles showed that the particles ranging from 2.00 to 6.84 microm constituted more than 80% of the total particles. The secondary effluent was relatively poor biodegradable with only 0.195-0.283 of BOD5/COD ratio and 0.156-0.26 of BDOC/DOC ratio. The GC/MS analysis detected 43 and 26 kinds of compounds in dissolved and in suspended forms, respectively, and most of them are bio-refractory according to the functional groups of the chemicals. Biodegradability of the secondary effluent should be enhanced for improving the sequential biochemical removal efficiency for the organic matter.
Wang
Shu-Tao
ST
School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China. wshutao@yahoo.com.cn
Wang
Hong
H
Ma
Jun
J
Zhang
Guang-De
GD
Liu
Hui-Ling
HL
D002681:China; D002947:Cities; D010316:Particle Size; D012621:Seasons; D014865:Waste Disposal, Fluid / Q000379:methods*; D014867:Water / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
D014867:Water