Chemical and microbial similarities and heterogeneities of wastewater from single-household cesspits for decentralised water reuse

ABSTRACT In Brandenburg, Germany, 8% of households rely on single-household cesspits for wastewater collection. This study analysed the chemical and microbial characteristics of wastewaters from 12 single-household cesspits and pit lorry samples to assess their suitability for water reuse. The analyses include physico-chemical parameters (pH, electrical conductivity, chemical and biochemical oxygen demand, total nitrogen, ammonium, phosphorus), 11 heavy metals, 67 organic trace substances, and bacteria concentrations. Measurements showed strong similarity across single-household cesspits for pH, electrical conductivity, Shannon Index and Richness of the microbial communities. In contrast, there was high variability across cesspits for oxygen demand, nitrogen, phosphorus, heavy metals, organic trace substances and total and damaged bacteria concentrations. Comparison with municipal wastewater showed that cesspits contained higher concentrations of organic and inorganic pollutants, which may be related to household-specific use patterns and limited dilution by wastewater from other sources. Physico-chemical analyses indicate that cesspits contained mainly easily degradable organic substances. The high variability of wastewater from cesspits points to the need for flexible treatment approaches. The results enhance the understanding of composition of wastewater from decentralised sources in Central Europe and support efforts towards sustainable water management and the development of adaptable treatment solutions for different wastewater compositions.