[Elasticity plastic filler for purification of polluted streams in situ entering lake].

The biofilm process using a new-type elasticity plastic filler was adopted in a typical polluted stream entering the Tai Lake (the Linzhuanggang). The experiments at pilot scale ran for about 0.5 years. Results show the average removal percentage of permanganate index by biofilm attached to the elasticity plastic filler is about 5.4%, the biggest removal percentage is 9.9%, the average removal percentage of NH(4+) -N is approximately 5.35%-39.91%, the biggest removal percentage of TP is 28.6%. And the bacteriological experimental results show there is the same change laws between the removal percentage of permanganate index and the numbers of heterotrophic bacteria; the numbers of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) are matching with removal of NH(4+) -N.

[Experiment and model simulation of suspended solids in Taihu Lake under wind-wave disturbance].

The bottom mud in Taihu Lake was simulated indoors in a wave tank. The rules of starting principle of the bottom mud were analyzed under different kinds of disturbing intensity in this paper. The common wave intensity of Tai Lake could be systematically simulated in the wave tank. The critical sheer stress of bottom mud in Tai Lake is 0.050Pa by the experiment. The calculated result of the flow field and suspended solids from the advanced model of FVCOM conforms to the observation data in Taihu Lake very well, which proves validity of the model. Because the conflict of field observation data in time and space greatly influences the accuracy of model parameters, simulating the suspended solids indoors is very important to the cure of Eutrophication in Taihu Lake.

[Simulation and model computation on dynamic release of nutrition factors of bottom mud in Taihu Lake].

The dynamic release of bottom mud in Taihu Lake was simulated indoors in an annular tank. The rules of starting principle, resuspension and release rate of bottom mud were analyzed under different kinds of disturbing intensity. The velocity of flow was basically uniform in the annual tank. Both the rotation rate of the tank and the velocity of flow can be controlled precisely. The relational expression between the release rate of TN, TP (y) and flow velocity (x) was calculated on the basis of the relationship between them. The calculated result from the model of ECOMSED conforms to the observation data in Taihu Lake very well. Because the conflict of field observation data in time and space greatly influences the accuracy of model parameters, simulating the dynamic release of bottom mud indoors is very important to the cure of eutrophication in Taihu Lake.

Distribution of extractable fractions of heavy metals in sludge during the wastewater treatment process.

Sludge samples were collected from different treatment steps of Gaobeidian wastewater treatment plant (WWTP) of Beijing City, PR China, to investigate the distributions of total and chemical fractions of Fe, Mn, Ni, Cu, Zn, Cr, Pb, and Mo in different sludges. The highest total concentrations were found for Fe, Mn, Pb, and Mo in digested sludge (DS), Ni and Cr in thickened sludge (TS), Zn in dewatering sludge (DWS), and Cu in active sludge (AS). The lowest concentrations were observed in AS, except for Cu in TS. Significant differences of total metal concentration were observed between AS and TS (or DS), suggesting that sludge thickening and digesting treatments significantly influenced the total metal concentrations. Fe, Cu, Ni, Cr, Mo, and Pb distributed principally in the residual fraction in all sludges, while Zn and Mn presented in a highly available fraction. For same metal in different sludges, the portion of easily mobile fraction decreased significantly along the wastewater treatment process, and metals in AS presented in the highest available fraction. Organic matter contents, TN, and TP of sludges exhibited a significant positive correlation with the concentrations of exchangeable and reducible fraction of Pb, Mo, Cr, Cu, and Fe, while sludge pH demonstrated significant negative correlations with the concentrations of these metals.