The effect of a two-step process on the concentration of pathogens and indicator microorganisms in black water (0.9–1% total solids) was studied. The treatment combined auto-thermal aerobic digestion (ATAD) and ammonia sanitisation. First, the temperature of the black water was increased through ATAD and when a targeted temperature was reached (33, 41 and 45.5 °C studied), urea was added to a 0.5% concentration (total ammonia nitrogen >2.9 g L−1). Escherichia coli and Salmonella spp. were reduced to non-detectable levels within 3 days following urea addition at temperatures above 40 °C, whereas when urea was added at 33 °C E. coli was still present after 8 days. By adding urea at temperatures of 40 °C and above, a 5 log10 reduction in Enterococcus spp. and a 3 log10 reduction in Ascaris suum eggs was achieved 1 week after the addition. With combined ATAD and ammonia treatment using 0.5% ww urea added at an aerobic digestion temperature >40 °C, black water was sanitised regarding the pathogens studied in 2 weeks of total treatment time.
Sanitising black water by auto-thermal aerobic digestion (ATAD) combined with ammonia treatment
Annika C. Nordin, Björn Vinnerås; Sanitising black water by auto-thermal aerobic digestion (ATAD) combined with ammonia treatment. Water Sci Technol 16 December 2015; 72 (12): 2112–2121. doi: https://doi.org/10.2166/wst.2015.432
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