76 / 2021-06-30 16:23:15

Evaluation of nitrification performance of wastewater from activated sludge solid waste treatment plant

Activated sludge; Solid waste treatment; Nitrification; Ammonia-oxidising bacteria; Cell-specific ammonia oxidation rate (CSAOR)

Excess ammonia, nitrite and nitrate in rivers and streams can cause eutrophication and pose a risk to human and environmental health. Wastewater treatment plants (WWTPs) usually use the metabolic capacity of microorganisms to remove excess nutrients, such as organic carbon, ammonia and phosphorus. Different groups of microorganisms make up the activated sludge microbial community used to remediate wastewater. Nitrification is one of the central microbial processes in wastewater treatment. Under aerobic conditions in the wastewater treatment process, nitrifying microorganisms oxidise ammonia to nitrate. Under anaerobic conditions, denitrifying bacteria reduce nitrate to gaseous nitrogen, both of which ultimately reduce the dissolved nitrogen concentration of the wastewater.

The report evaluated the nitrification performance of 23 activated sludge WWTPs by analysing laboratory data on mixed liquor suspended solids (MLSS) (Figure 1), ammonium and ammonia-oxidising bacteria (AOB), discusses the relationship between ammonium removal efficiency, quantification of AOB and cell-specific ammonia oxidation rate (CSAOR) (Figure 2). Four conclusions can be seen: 1) Within a certain range of (ammonia-oxidising bacteria) AOB concentrations, the higher the concentration of AOB, the higher the conversion to ammonium. 2) There is a negative correlation between AOB cell concentration and CSAOR (Figure 2). 3) A graph of the concentration of AOB against CSAOR can be used to potentially manage the operation of wastewater treatment. 4) In addition to Fluorescence in situ hybridisation (FISH), Flow cytometry (FCM) and Quantitative real-time fluorescence PCR (qPCR) can also quantify AOB content in activated sludge wastewater.