Membrane filtration coupled with chemical precipitation to treat recirculating aquaculture system effluents.
Effluents from recirculating aquaculture systems (RAS) contain high concentrations of nitrogen and phosphorous wastes and thus often require proper treatment to prevent potential detrimental impacts on receiving water bodies. The purpose of this study was to evaluate the feasibility of membrane filtration coupled with chemical precipitation as a pretreatment step with emphasis on phosphorus removal from RAS effluents. Chemical precipitation tests were conducted by adding magnesium chloride and alum at different chemical concentrations and pH values, respectively. Crossflow, flat-sheet membrane filtration modules were used to examine the effects of transmembrane pressure and crossflow velocity in terms of solid/liquid separation efficiency and permeate flux decline. The results showed that membrane filtration can effectively separate the phosphorus precipitates after chemical precipitation. The total phosphorus in the treated effluent was reduced to less than 0.05 mg L(-1) with a removal efficiency of more than 90%. However, much lower removal efficiencies were obtained for total organic carbon (TOC), total nitrogen, and turbidity. It was concluded that membrane filtration coupled with chemical precipitation can become an effective, compact treatment technology to meet the stringent regulatory requirements for RAS effluent discharge.
Yang
Ling
L
School of Engineering, University of Guelph, Guelph, Ontario N1G 2W1.
Zhou
Hongde
H
Moccia
Richard
R
D000534:Alum Compounds / Q000737:chemistry; D017756:Aquaculture; D002244:Carbon / Q000302:isolation & purification; D011232:Chemical Precipitation; D005374:Filtration; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste / Q000009:adverse effects / Q000517:prevention & control; D015636:Magnesium Chloride / Q000737:chemistry; D008567:Membranes, Artificial; D009391:Nephelometry and Turbidimetry; D009584:Nitrogen / Q000302:isolation & purification; D009930:Organic Chemicals / Q000302:isolation & purification; D010758:Phosphorus / Q000302:isolation & purification; D014865:Waste Disposal, Fluid / Q000379:methods*; D018508:Water Purification / Q000379:methods*
D000534:Alum Compounds; D007220:Industrial Waste; D008567:Membranes, Artificial; D009930:Organic Chemicals; D015636:Magnesium Chloride; D010758:Phosphorus; C041524:aluminum sulfate; D002244:Carbon; D009584:Nitrogen