To develop urban stormwater management effectively, characterization of urban runoff pollution between dissolved and particulate phases was studied by 12 rainfall events monitored for five typical urban catchments. The average event mean concentration (AEMC) of runoff pollutants in different phases was evaluated. The AEMC values of runoff pollutants in different phases from urban roads were higher than the ones from urban roofs. The proportions of total dissolved solids, total dissolved nitrogen, and total dissolved phosphorus in total ones for all the catchments were 26.19%–30.91%, 83.29%–90.51%, and 61.54–68.09%, respectively. During rainfall events, the pollutant concentration at the initial stage of rainfall was high and then sharply decreased to a low value. Affected by catchments characterization and rainfall distribution, the highest concentration of road pollutants might appear in the later period of rainfall. Strong correlations were also found among runoffs pollutants in different phases. Total suspended solid could be considered as a surrogate for particulate matters in both road and roof runoff, while dissolved chemical oxygen demand could be regarded as a surrogate for dissolved matters in roof runoff.

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Bio-stability and health security of drinking water have become basic requirements to protect human health. The conventional water purification process, which is composed of coagulation, sedimentation, filtration and disinfection, can not solve the problems of organic matters in the micro-polluted source water effectively. So the by-products generated in the chlorination disinfection increased the carcinogenic risks of drinking water. The higher concentrations of Fe, Mn and trace heavy metals in the water are also harmful to health. In this study, bio-sand filter was adopted to treat the micro-polluted source river water. UV 254 was used as a controlling parameter to measure the organic matters, BDOC and TP were used as evaluation parameters to measure the bio-stability of water quality. Combined with the removal of Fe, Mn and trace heavy metals in the source water, the effects of bio-sand filter on improving the health security and bio-stability of drinking water were investigated. The results demonstrate that bio-sand filter has good removal of UV 254 , and the average removal is 37.13%. The average removal of Fe, Mn and trace lead and chromium are 74.75%, 76.55%, 74.07% and 68.82%, respectively. The bio-sand filter has good removal of BDOC and TP. The average removal of BDOC is 61.78%. The removal of TP ranges from 58.76% to 78.53%, and the average removal is 68.62%. Applying the biofiltration process in the water purification process can remove the biodegradable natural organic matters and control the production of disinfection byproducts, as well as the re-growth of micro-organisms in the water distribution system. The bio-sand filter process can remove Fe, Mn and trace heavy metals from the micro-polluted source water effectively. The bio-sand filter has great significance to improve the bio-stability of water quality, to limit the re-growth of microorganisms in the water distribution system and to protect human health.

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a b s t r a c tA bench-scale university of cape town-membrane bioreactor (UCT-MBR) process was operated treating real municipal wastewater with reference to the synergistic effects of aeration intensity and mixed liquor recycling ratio on biological nutrient removal performance and membrane fouling propensity. Results showed that chemical oxygen demand (COD) and NH 4 + -N removal was slightly dependent on variations in aeration intensity and recycling ratio. The increase in recycling ratio strengthened the enrichment of denitrifying poly-phosphate accumulating organisms (DPAOs) and the anoxic dephosphorization efficiency. The largest ratio of DPAOs to poly-phosphate accumulating organisms (PAOs) (50.7%) could be obtained when a low aeration intensity (100-125 L/h) and the highest recycling ratio (r 1 : 400%) were demonstrated. In contrast, a higher aeration intensity level (250-300 L/h) resulted in the deterioration of the anoxic dephosphorization efficiency, decreasing to 78%, 77.03% and 70% from 93%, 92.6% and 79.6% (r 1 from 400% to 200%), respectively. The bio-cake resistance was significantly reduced by a higher aeration intensity notwithstanding higher concentrations of extracellular polymeric substances (EPS). The combined shear forces induced by these two parameters promoted the smaller-size particles and higher concentrations of soluble microbial products (SMP) in the bulking sludge which resulted in the increased resistance of deep pore clogging. Fourier transform infrared spectroscopy (FT-IR) analysis revealed that variations in these two parameters had no effect on the main composition of organic matters in the membrane foulants.