Influence of Microwave Radiation on Pollutant Removal and Biomethane Production Efficiency in Anaerobic Treatment of High-Load Poultry Wastewater

The growing consumption of poultry meat has spurred the development of meat-processing plants and an associated rise in wastewater generation. Anaerobic digestion is one of the preferred processes for treating such waste. The current push towards biogas upgrading and out-of-plant use necessitates new, competitive ways of heating digesters. One such alternative is to use electromagnetic microwave radiation (EMR). The aim of the study was to assessment how EMR used as a heat source impacts the anaerobic processing of high-load poultry slaughterhouse wastewater (H-LPSW) and its performance. Microwave heating (MWH) was found to boost the CH4 fraction in the biogas under mesophilic conditions (35 degrees C) as long as the organic load rate (OLR) was maintained within 1.0 kgCOD/dm(3)center dot d to 4.0 kgCOD/dm(3)center dot d. The best performing variant-EPM heating (55 degrees C), OLR = 3.0 kgCOD/dm(3)center dot d, HRT = 5 days-produced 70.4 +/- 2.7% CH4. High COD and TOC removal, as well as the highest biogas yields, were achieved for loadings of 1.0 gCOD/dm(3)center dot d to 4.0 gCOD/dm(3)center dot d. Effluent from the EMR-heated reactors (1.0 gCOD/dm(3)center dot d) contained, on average, 0.30 +/- 0.07 gO(2)/dm(3) at 55 degrees C and 0.38 +/- 0.10 gO(2)/dm(3) at 35 degrees C. The corresponding COD removal rates were 97.8 +/- 0.6% and 98.1 +/- 0.4%, respectively. The 5.0 gCOD/dm(3)center dot d and 6.0 gCOD/dm(3)center dot d OLR variants showed incremental decreases in performance. Based on the polymerase chain reaction results of 16S rDNA analysis, diversity of bacterial communities were mostly determined by OLR, not way of heating.

Automated summary

The increase in poultry meat consumption has led to the growth of meat-processing plants and an increase in wastewater generation. Anaerobic digestion is a preferred method for treating this waste. The use of electromagnetic microwave radiation (EMR) as a heat source can enhance the anaerobic processing of high-load poultry slaughterhouse wastewater (H-LPSW). The best performance was achieved with an OLR of 3.0 kgCOD/dm(3)center dot d, producing 70.4 +/- 2.7% CH4. The effectiveness of EMR heating was influenced by the OLR rather than the way of heating, as determined by bacterial diversity analysis.