Search

The removal of total nitrogen in wastewater treatment plants (WWTPs) is often unsatisfactory for a variety of reasons. One possible measure to improve nitrogen removal is the addition of external carbon. However, the amount of carbon addition is directly related to WWTP operation costs, highlighting the importance of accurately determining the amount of external carbon required. The objective of this study was to obtain a low nitrate concentration in the anoxic zone of WWTPs efficiently and economically by optimizing the external carbon source dosage. Experiments were conducted using a pilot-scale pre-denitrification reactor at a Nanjing WWTP in China. External carbon source addition based on online monitoring of influent wastewater quality and a developed nitrification-denitrification numerical model was investigated. Results showed that carbon addition was reduced by 47.7% and aeration costs were reduced by 8.0% compared with those using a fixed-dose addition mode in the pilot reactor. The obtained technology was applied to the full-scale Jiangxinzhou WWTP in Nanjing with promising results. [ABSTRACT FROM AUTHOR]

We describe a simple, cost-effective approach for surface modification of various substrates with SnO2 nanoparticles by controlled hydrolysis, which is not confined on specific chemical states of the surface. Specifically, these SnO2 nanoparticles were loaded onto the surfaces of carbon-based materials (graphene), ionic crystals (tin sulfide), polymer materials (silk fiber) and biological materials (yeast) with uniform distribution, despite the great differences in surface chemistries. Moreover, the formation mechanism of the SnO2 nanoparticles has been discussed, confirming that the process described can be easily implemented and adapted to other systems. These as-synthesized nanocomposites are expected to have wide applications in the fields of gas sensing, photocatalysis and biomaterials. [ABSTRACT FROM AUTHOR]

Mathematical models based on instant environmental inputs are increasingly applied to optimize the operation of wastewater treatment plants (WWTPs) for improving treatment efficiency. This study established a numerical model consisting of the activated sludge module ASM3 and EAWAG bio-P module, and calibrated the model using data from a full-scale experiment conducted in a WWTP in Nanjing, China. The calibrated model was combined with online sensors for water temperature, chemical oxygen demand, NHþ 4 -N and PO3- 4 -P to optimize and dynamically adjust the operation of the WWTP. The results showed that, compared to the original default operation mode, the effluent water quality was significantly improved after optimization even without supplementation of external carbon or alkalinity, and the required aeration rate in spring, summer, autumn, and winter was reduced by 15, 41, 33 and 11%, respectively. The study indicated that there was the potential for application of closed-loop automatic control to regulate operating parameters to improve wastewater treatment processes through the integration of data on influent characteristics and environmental conditions from sensors, and results from simulation models. [ABSTRACT FROM AUTHOR]