Phosphorus removal characteristics of a combined AS-biofilm process cultured by different COD/TP ratios

Performance evaluation of A2O MBR system with graphene oxide (GO) blended polysulfone (PSf) composite membrane for treatment of high strength synthetic wastewater containing lead

High strength synthetic wastewater containing 5 mg L^-1 of lead was studied for treatment using an A2O MBR system. The system showed 99% removal of ammonia and COD, a maximum removal of 52% of total phosphorus and an average minimum removal of 72% of total nitrogen. A maximum lead removal of 98% was achieved for hydraulic retention time (HRT) of 144 h, which decreased to 85% when the influent COD concentration was decreased. Mass balance for lead revealed that much of its removal was through accumulation by the biomass present in the anaerobic and anoxic tanks. Comparative study on virgin PSf and GO blended PSf membrane showed that the GO blended membrane lasted 1.4 times longer than the other. SEM-EDS of membranes showed lead peaks on the fouled and un-fouled sections of the membranes indicating the association of lead with the foulant and the role of membrane in lead separation. Good separation efficiency was achieved irrespective of the membranes used.

Development of biofilm on geotextile in a new multi-zone wastewater treatment system for simultaneous removal of COD, nitrogen and phosphorus

This study investigated the formation and evolution of biofilm on a fixed cylindrical structure wrapped in geotextile, in a multi-zone wastewater treatment system called BioCAST. The organic, nitrogen and phosphorus loading rates of (OLR) 0.95-1.86 g COD/(m(3)d), (NLR) 0.02-0.08 kg N/(m(3)d), and (PLR) 0.014-0.02 kg P/(m(3)d), were applied. The results demonstrated high removal efficiencies of carbon, nitrogen and phosphorus, reaching 98.9%, 98.3% and 94.1%, respectively, after 250 d of operation. The biofilm biomass showed a fast formation (reaching 54.2g/L) and maximum phosphorus content of about 7% (dry basis). Biofilm demonstrated the ability to remove phosphorus, and its characteristics correlated with nitrogen and phosphorus removal rates. The geotextile material with filamentous structure causing rapid attachment and formation of biofilm can solve many problems encountered in conventional attached-growth wastewater treatment systems such as slow start-up, low reactor biomass content and low capacity to handle high organic loading rates.

Treatment of a slaughterhouse wastewater: effect of internal recycle rate on chemical oxygen demand, total Kjeldahl nitrogen and total phosphorus removal

This study investigated the ability of an anaerobic/anoxic/oxic (A2/O) system to treat a slaughterhouse wastewater. The system employed two identical continuous-flow reactors (101 total liquid volume each) running in parallel with the main operational variable, being the internal recycle (IR) rate. The chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN) and total phosphorus (TP) performance was evaluated as the IR flowrate was increased from a Q of 151d(-1) to 4Q at a system hydraulic retention time of 16 h and a solids retention time of 10 d. The COD:TKN and COD:TP ratios were 8.2:1 and 54:1, which supported both nitrogen and phosphorus removal. For all IR multiples of Q, the COD removal was in excess of 90%. The TKN removal showed a modest improvement (a 4-5% increase, depending on the dissolved oxygen (DO)) as the IR doubled from Q to 2Q, but no further increase was observed at the 4Q IR rate. The TP removal reached its optimum (around 85%-89% (again depending on the DO)) at the 2Q rate.

Heavy metal removal from aqueous solution by wasted biomass from a combined AS-biofilm process

This study evaluated the capability of metal biosorption by wasted biomass from a combined anaerobic-anoxic-oxic (A2O)-biofilm process with simultaneous nitrogen and phosphorus removal. Zinc, cadmium and nickel were rapidly adsorbed in 20 min by the harvested sludge from a continuous-flow pilot-plant. Biosorption equilibrium was then reached in 6h. The biosorption isotherm showed that metal biosorption behavior had fitted well to the Freundlich isotherm, but not Langmuir isotherm. The capacity constants k of Freundlich model for nickel, zinc and cadmium were 0.471, 0.298 and 0.726, respectively; the affinity constants 1/n were 0.444, 0.722 and 0.718, respectively. The order of metal affinity for the wasted biomass was Zn > Cd > Ni, which was in conformity to the other biosorption results with different biological sludge.