Results of life cycle inventory (LCI) and life cycle assessment (LCA) for septic tanks collecting domestic sewage were presented. The study included the whole life cycle: construction, use and end-of-life stages of septic tanks. The analyses were conducted basing on actual data concerning performance of 793 septic tanks in Żory. Environmental impact assessment of the life cycle of septic tanks was conducted with TRACi and ReCiPe methods. Greenhouse gas (GHG) emission, eutrophication, fossil fuel depletion and metal depletion indicators were calculated and determinants of LCA of septic tanks were analysed. The system boundary was from cradle to grave. It was concluded that at the construction stage, GHG emission and fossil fuel depletion indicators are determined by the amount of concrete, steel, polyester resin, polyethylene, cast iron and PCV. At the use stage, GHG emission is determined by the amount and type of electricity used to treat sewage in a wastewater treatment plant (WWTP). Untreated wastewater, introduced into the environment (leaking tanks and users discharging sewage), is a determinant of infl uence on eutrophication. Life cycle inventory and environmental assessment of septic tanks with life cycle perspective are presented in the literature for the fi rst time. The results highlight the importance of including each stage in the environmental assessment of elements of the urban wastewater system.

The objective of this study is to assess the physical-chemical quality of urban wastewater from the city of Boumerdès, in northern Algeria with regard to the threshold values for irrigation or their discharge in aquatic ecosystems. Five sampling points were carried out of the study area in April 2017. The results obtained of physical- chemical parameters indicating pollution show that the water course is exposed to pollution mainly of organic origin. It’s expressed by a high maximum value according to Algerian and World Health Organisation standards: chemical oxygen demand ( COD 886 mg O ₂∙dm ^–3), biochemical oxygen demand ( BOD ₅ 490 mg O2∙dm ^–3), nitrate (NO ₃ ^– 73.09 mg∙dm ^–3), nitrite (NO ₂ ^–6 mg∙dm ^–3), ammonium (NH ₄ ⁺ 23 mg∙dm ^–3) and phosphates (PO ₄ ^3– 7.3 mg∙dm ^–3). The COD to BOD ₅ rate of 1.8, show that the effluents must be treated before being discharged into the receiving environment. However, it is lower than 2, which makes them easily biodegradable and can be treated by a biological system such as a natural lagoon. It shows also a diversified origin of the pollution. It is predominantly domestic origin, it could have an adverse effect on public health, presenting a risk of environmental eutrophication, contamination of soil and water resources. The physical-chemical characterisation of the urban wastewater shows that they are quite loaded and present a pollution in nitrogenous compounds, a treatment is requested before the direct discharge to the receiving environment or their reuse in the irrigation.