Combined UMBAF-MBAF process treating detergent wastewater.

A combined process of the upflow multimedium biological aerated filter (UMBAF) and the multimedia biological aerated filter (MBAF) treating detergent wastewater was investigated in this study. Results showed that the optimal filtration rate of the combined system was 1.4 m/hr while the optimized performance was observed at air to water ratio of 2:1. The average removal rate of chemical oxygen demand (COD), linear alkyl benzene sulfonate sodium (LAS), and total phosphate (TP) was up to 91.4%, 88.5%, and 40%, respectively, while the average effluent concentrations of COD, LAS, and TP under stable operation states were 35.0 mg/L, 7.0 mg/L, and 4.4 mg/L, respectively. UMBAF played a major role in TP removal; the removal of COD in the combined UMBAF and MBAF process was consistent with the general formula C = C0 e -(ah + b) , while the kinetic model of LAS removal in the combined UMBAF and MBAF process could be expressed by L = L0 e-(mh + n) . The combined UMBAF-MBAF process provides a promising technology for the treatment of detergent wastewater. The kinetic model of LAS removal in the UMBAF and MBAF units is helpful for the prediction of the treatment efficiency of organic pollutants. PRACTITIONER POINTS: A novel UMBAF-MBAF process was developed treating detergent wastewater. The average removal rate of COD, LAS, and TP by the combined process was up to 91.4%, 88.5%, and 40%, respectively. Kinetic models for the UMBAF-MBAF process were investigated.

Effects of hairy crab breeding on drinking water quality in a shallow lake.

The Yangcheng Lake, connected to Taihu, is partly served as drinking water source for Suzhou, China; the temporal and spatial changes of water quality parameters of it are investigated in this study. The Yangcheng Middle Lake with aquaculture area and the Yangcheng East Lake with important water intake are chosen to make a comparative investigation of the relationship between crab breeding and water quality. Phytoplankton community and the composition of dissolved organic matters (DOM) at different areas of the Yangcheng Lake are characterized with spectral fluorescence signatures. Results reveal that biopolymers and humic substances (HS) are the two major DOM compositions in the Yangcheng Lake. In the Yangcheng Middle Lake, the CODMn concentration at the large breeding area was lower than that in most other areas; while the concentration of algae and HS fluorescence intensity are positively correlated with each other in the Yangcheng Middle Lake. Crab breeding could accelerate nitrogen transformation and utilization. In summer and winter, the cumulative risk of building up potential harmful by-products such as DPBs caused by the biopolymers and HS is greater; the breeding of hairy crabs could reduce biopolymers and improve drinking water safety.