A comparative study of the industrial discharges effect on the anaerobic treatment of domestic wastewater in both experimental and pilot-plant scales

The aim of this study was to compare the effect of industrial discharges on the anaerobic treatment of domestic wastewater in both laboratory and pilot-plant scales at mesophilic conditions. The laboratory experiment results have shown the low process efficiency of anaerobic treatment of DW by the use of an adapted or a non-adapted methanogenic inoculum. These experiments performed in batch digesters were further confirmed by scaling up to a pilot-plant anaerobic membrane bioreactor (MBR). The treatment inefficiency in both laboratory and pilot-plant experiments could be related to the presence of toxic compounds due to the wastewater contamination by industrial discharges. The toxic character of DW was proved by the phytotoxicity and microtoxicity tests. Indeed, the luminescence inhibition percentages started at an average of 21% in the morning and reached more than 84% in the late afternoon. Moreover, the toxicity results have shown a direct relation with methanization results. Indeed, when the average microtoxicity increased to 73%, the average germination index value and the methanization efficiency expressed as the average methane percentage in the produced biogas decreased to 0% and 14.5%, respectively.