Organic loads have been significantly reduced in nightsoil plants along with the employment of sewage treatment plants. Nightsoil consisting of 10% septage and showing higher ratios of alkalinity and carbon to nitrogen helped nitrification and denitrification for those combined plants with weak piggery waste. However, alkalinity and carbon addition was necessary with the weak nightsoil consisting of 80% septage when the combined influent was less than 21 g/L COD. The piggery waste could be applied at a rate of 0.5 kgTKN/oxic m3/d, but the organic load should be limited to 0.7 kgCOD/m3/d with strong piggery waste during summer in order not to exceed the reactor temperature higher than 35°C.

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