Wastewater treatment using quicklime at the Kaf Dukhan station, Algeria

This study focuses on enhancing wastewater treatment in the city of Ghardaïa, Algeria, using locally sourced lime (calcium oxide, CaO). The research targets the Kaf Dukhan wastewater treatment plant, which relies on natural lagooning but lacks advanced tertiary treatment to improve water quality. The study proposes the use of local quicklime, extracted from a nearby traditional plant, to reduce pollutants such as Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), Suspended Solids (SS), nitrogenous compounds, and to regulate pH levels. Lime production involves extracting calcium carbonate (CaCO₃), calcining it in specialized kilns, and processing it into a fine powder. Physico-chemical analyses demonstrated significant improvements in water quality after lime treatment, with increased dissolved oxygen levels, reduced electrical conductivity, and a decrease in COD from 131 mg/L to 102 mg/L, while BOD levels dropped from 59 mg/L to 7 mg/L, indicating a considerable reduction in organic pollutants. Additionally, the treatment effectively reduced ammonium concentrations while slightly increasing nitrate and nitrite levels, a natural part of the nitrogen cycle during treatment. The findings confirm that the use of locally sourced lime is a cost-effective and efficient method for enhancing wastewater treatment processes in Ghardaïa, making the treated water more suitable for agricultural reuse or environmental discharge.