Improved alkaline stabilization of municipal wastewater sludge.
In Mexico, physicochemical sludge contains high levels of pathogens; and alkaline stabilization is an alternative for their control. However, the odours caused mainly by ammonia generation represent a disadvantage. On the other hand, the ammonia is known as an effective disinfectant. The aim of this study was to evaluate the disinfectant properties of ammonia in sludge, and use it in a closed alkaline stabilization system, which, not only copes with odours but also increases the efficiency of the process. Raw sludge from a municipal wastewater treatment plant using a physicochemical process was used. Ammonia was applied in doses from 10 to 50% w/w; also, doses from 5 to 40% of CaO were applied in open and closed systems and raw and treated sludge quality was evaluated. Results showed that ammonia removed 6 and 5 logs of faecal coliforms and Salmonella spp., respectively and up to 94% of viable helminth ova. The closed system was more efficient than the open system when applying doses from 5 to 20% of CaO. Finally, the results indicate that the ammonia represents an alternative to disinfecting wastewater sludge and it can be used to enhance alkaline stabilization processes.
Méndez
J M
JM
Instituto de Ingeniería UNAM, Apartado Postal 70-402, Ciudad Universitaria, 04510 Coyoacan, Mexico, D. F.
Jiménez
B E
BE
Barrios
J A
JA
D000641:Ammonia / Q000032:analysis*; D004202:Disinfectants; D004755:Enterobacteriaceae / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D008800:Mexico; D012475:Salmonella / Q000302:isolation & purification; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology; D014865:Waste Disposal, Fluid / Q000379:methods*
D004202:Disinfectants; D012722:Sewage; D000641:Ammonia