ABSTRACT
Many articles have been published on coagulant dosing in membrane bioreactors, though few have been long-term studies examining the treatment of real wastewater. This study summarises the results of a membrane bioreactor pilot-plant (flat sheet membrane, nominal pore size 0.03 µm) that treated real municipal wastewater for two-years. Both influence of phosphorus precipitation by ferric sulphate on membrane permeability (flux decrease) and soluble microbial product concentration (especially on carbohydrates and proteins) were monitored. Flux decrease over work cycles lasting several months without phosphorus precipitation were compared to two periods with precipitation. X-ray elemental diffractometry of the filtration cake showed differences in the main contributors to inorganic fouling, with decreases in Ca and Si during operation with coagulant addition, and an increase in Fe.
Subject(s)
Bacteria, Anaerobic/metabolism , Bioreactors/microbiology , Membranes, Artificial , Ultrafiltration/instrumentation , Water Pollutants, Chemical/isolation & purification , Water Pollutants, Chemical/metabolism , Water Purification/instrumentation , Equipment Design , Equipment Failure Analysis , Fractional Precipitation , Phosphorus , SolubilityABSTRACT
A seasonally operated full-scale membrane bioreactor plant (flat sheet, 0.03 µm) treating municipal wastewater from a recreation facility was monitored for 2 years. In particular, membrane bioreactor operation characteristics and development and changes in extracellular polymeric substances and soluble microbial product concentrations were observed, which were both dependent on volume and quality of incoming wastewater. Microbiological effluent quality, nutrient removal efficiency and activated sludge characteristics were analysed on a regular basis. Correlations between activated sludge quality, extracellular polymeric substance and soluble microbial product concentrations were identified. Pathogen related changes in effluent quality during plant operation were also observed. Nutrient removal efficiency was very good, despite fluctuations in influent flow.
Subject(s)
Bioreactors/statistics & numerical data , Cities , Membranes, Artificial , Seasons , Waste Disposal, Fluid/methods , Water Purification/methods , Biological Oxygen Demand Analysis , Environmental Monitoring/methods , Environmental Monitoring/statistics & numerical data , Nitrogen/isolation & purificationABSTRACT
The main goal of this research was to investigate how different factors influence membrane fouling. The impact of the different concentrations of activated sludge and the amount of extracellular polymer substances (EPS) were monitored. Two pilot plants with submerged membrane modules (hollow fiber and flat sheet) were operated and the raw wastewater was used. Humic substances were identified as the major components of EPS in the activated sludge (more than 34%) in both pilot plants. As the basic constituent in permeate, humic substances were identified as the most dominant components in the effluent (61%) in both pilot plants. Conversely, proteins were mostly analyzed in permeate and supernatant below the detection limit. The total amount of EPS [mgg(-1) (VSS)] was similar for concentrations of activated sludge 6, 10 and 14 g L(-1). Carbohydrates were identified as the component of EPS which tends most to clog membranes.
