The surface characteristics, including rheological, fractal characteristics, hydrophobicity as well as surface free energy, of H2-producing sludge in acidogenic fermentative process were investigated in this study. Both rheological and fractal characteristics of the H2-producing sludge changed slightly in the acidogenesis. The sludge fractal dimension was larger than those of other microbial aggregates, whereas the affinity of the microbial cells for the hydrocarbon had a peak value in the fermentation process. Both specific H2 and volatile fatty acids/ethanol production rates of the sludge had a peak of 108 mL-H2 L-1 h-1 g-VSS-1 and 480 mg L-1 h-1 g-VSS-1. There was a relationship between the hydrophobicity of the H2-producing sludge and its specific H2-producing activity. The surface free energy of the H2-producing microorganisms had a lowest value in their growth process.
The present paper deals with absorption of heavy ions of Pb2+, Cd2+ in water on potassium tetratitanate whisker (PTW). The effects of quantity of PTW, time and pH value on the absorption is studied. The test results show that the absorption efficiency of PTW increases with the quantity of absorbent, time and pH value. The absorption of Pb2+ and Cd2+ ions on PTW follows Freundlich's Equation. The property of PTW regeneration is also investigated in the present paper. The possibility of using PTW to treat industrial waste water containing heavy metal ions is discussed.
The reduction of ammonia-nitrogen fluxes from polluted streams entering the Tai Lake is an important task in areas with limnetic eutrophication. Biofilm technique for the polluted streams has been proposed as one effective method to reduce ammonia-nitrogen fluxes entering the Tai Lake. In this study, ammonia-nitrogen biodegradation in a created biofilm purification engineering was evaluated by a dynamic model of ammonia-nitrogen in a polluted stream (Linzhuanggang) in western Tai Lake of China. The ammonia-nitrogen biodegradation model was described with Monod dynamic equation and hydraulic characteristic of the stream, and modified and evaluated by analyzing biodegradation effect in different periods and at different environmental conditions. Due to temperature dependence and seasonal variation in the stream, decrease in ammonia-nitrogen concentration mainly occurred during summer periods, which affected biodegradation effect of ammonia-nitrogen to some degree. The model showed that the purification engineering reduced the nitrogen transport to the Tai Lake with approximately 5%-40% in the test period.
The behavior of nitrite oxidizers in the nitrification/denitrification process for the treatment of coak-oven wastewater was studied by using molecular methods. An activated sludge process was operated with simulated coak-oven wastewater. In the existence of thiosulfate, partial nitrification was observed, while in its absence, full nitrification was observed. In the activated sludge treating simulated coak-oven wastewater, only Nitrobacter species were found as the nitrite oxidizers by using PCR and FISH targeted at different nitrite oxidizers. The QP-PCR (quenching primer PCR) method was applied for the quantitative monitoring of Nitrobacter species. The QP-PCR method demonstrated that Nitrobacter species increased when thiosulfate was absent. Nitrobacter species was found to have been the major nitrite oxidizing species at least in one of the operational periods with full nitrification. On the other hand, in another period with full nitrification, their absolute amount was too small to explain nitrite oxidation.
To quantify Candidatus ‘Accumulibacter phosphatis’ in activated sludge, quantitative PCR method was developed utilizing SYBR GREEN I and a specific primer set targeted on the 16S rRNA gene of Candidatus ‘Accumulibacter phosphatis’. Following optimization of PCR condition, specificity was evaluated based on the melting curve and the sequencing analysis of the PCR products with DNA extracted from activated sludge. Both the melting curve and the sequencing analysis of the PCR product showed that only the target DNA from Candidatus ‘Accumulibacter phosphatis’ was amplified. Standard curves with a series of tenfold dilution of the DNA from 16S rRNA gene fragment of Candidatus ‘Accumulibacter phosphatis’ gave R2 values greater than 0.999. The minimum detection limit was 1.0×103 copies per reaction. The amount of Candidatus ‘Accumulibacter phosphatis’ in laboratory-scale and full-scale activated sludge samples were quantified both by the quantitative PCR method and by the FISH method. The quantification results by these two methods agreed satisfactorily, with an R2 value of 0.6871 showing a statistically significant correlation (p<0.001). Thus, we developed a rapid quantification method by using quantitative PCR for the quantification of Candidatus ‘Accumulibacter phosphatis’ in activated sludge.