Meng Xuezheng

Nitrite accumulation during wastewater denitrification

Characteristics and mechanisms of nitrite accumulation during wastewater denitrification were reviewed based on our experimental results and literatures reports. Nitrite accumulation may be caused by the rate difference between nitrate reduction and nitrite reduction. It can also is the results of some species of bacteria or enzymes absence in the denitrification sludge. Although literature reports were inconsistency, temperature, dissolved oxygen, pH, types of carbon source and C/N ratios are the main environmental factors that have a big influence on nitrite accumulation. Nitrite is detrimental to aquatic organism if the wastewater containing enough nitrite was discharged to waters or can be a big problem for activated sludge process operation. Nitrite accumulated in denitrification may serve as electron donor for anammox reaction and the demonstration tests are undergoing in our lab.

Toxicology of Di-(2-ethylhexyl) phthalate in reclaimed wastewater and its removal options

Di-(2-ethylhexyl) phthalate (DEHP) is one of the typical endocrine disrupting chemicals found in water and wastewater. Concentrations of DEHP in water, wastewater and reclaimed wastewater are summarized based on published literatures. Concentrations of DEHP in source water for drinking or final sewage effluents sometimes definitely exceeded legal stipulations for DEHP limits in China. Although physicochemical and biological treatments are the main effective and practical technologies for DEHP removal from water or wastewater, they need further exploration. Novel sustainable treatment technology such as membrane separation processes is essentially needed.