Design strategy for a simultaneous nitrification/denitrification of a slaughterhouse wastewater in a Sequencing Batch Reactor: ASM2d modeling and verification.

Sequencing Batch Reactor (SBR) was used to treat slaughterhouse wastewater which contains average Chemical Oxygen Demand (COD) concentration of 5000 mg l(-1) and ammonium of 360 mgN l(-1). Nitrification/denitrification process was conducted for nitrogen removal. The influent wastewater as internal carbon source and sodium acetate as an external one was used for completing denitrification to achieve the simultaneous organic matter removal (95-96%) and nitrogen removal (95-97%). In addition, the dynamic SBR simulation model for biological nitrogen removal based on the Activated Sludge Model No. 2d (ASM2d) and GPS-X software is presented. The experimental study for the calibration and validation of the model was carried out using laboratory SBR. The study showed that the model provides a powerful tool to reduce the experimental expenditure and time to find the optimum strategy.

Treatment of slaughterhouse wastewater in a sequencing batch reactor: simulation vs experimental studies.

In wastewater treatment, the objective of process optimization is primarily to obtain a good treatment efficiency of a specific pollutant. The operational objective of increased productivity has also to be met. This includes a sufficient reduction in the duration of a batch process through batch scheduling. The aim of this paper is thus to find the best cycles for simultaneous carbon, nitrogen and phosphorus (CNP) removal from slaughterhouse wastewater in a sequencing batch reactor (SBR) using GPS-X software and ASM2d model. Simulations with different aeration strategies, residence time, sludge age and feed strategies were carried out to determine the best system performance. The simulation results showed best performance with a system comprised of two equal feeds operated at 48 h hydraulic retention time (HRT) and 20 d solids retention time (SRT). Simulation also showed that addition of metal salts was necessary to reduce the level of phosphorus (P) to meet the requirement (P<1 mg l(-1)). The addition of acetate was also necessary to complete the denitrification process. The simulated results were compared against the experimental results obtained from laboratory SBR. The simulated results of COD, nitrates/nitrites and ammonia removal were very close to the experimental results. A diference of 2-4% between the simulated COD and the experimental COD was observed and that could be attributed to the error in evaluation of the inert COD. For ammonia removal, the simulated (99.9%) and experimental (93-100%) results were practically identical. However, a notable difference in o-PO4 concentration was observed (38% removal by simulation against 78% removal through experiments). After metallic salts addition, P removal efficiency was 98% or 1% less than that observed through experimental results.