Evaluation of the Fertilizing Power of Sludge from Physicochemical Water Purification Stations: Case of the Yato Station, Littoral-Cameroon

Abstract

The Yato physicochemical water purification station is located in the commune of Dibombari in the Littoral-Cameroon region. It is one of the largest drinking water production stations in the Central African sub-region. This work aims to evaluate the agronomic power of the sludge from this drinking water production station. To achieve this objective, mixed samples of sludge from sludge treatment basins (taken according to the technique described in GIDS-A003 point 6 as explained in the Solid and pasty waste sampling strategy of the Code of Good Practice No. 2). and primary settling basins (collected in transparent 1.5L polyethylene terephthalate bottles) were analyzed. Likewise, three soil samples (marsh, Point 1 and Point 2) were taken and then sent to the laboratory where physicochemical analyzes were carried out. The characteristics of the samples that were analyzed are: particle size, texture (sand, silt, clay) and physicochemistry (organic matter, CEC, sum of exchangeable bases, calcium, nitrogen, potassium and magnesium). The results obtained show that the soils exposed to contamination from the sludge of the station have better agronomic properties both on a physical level with a stable structure favorable to plant growth and good aeration unlike the soils far from the station which presented a high risk. degradation; that on the chemical level with an optimal cationic balance, a high reserve of exchangeable bases, a strong CEC but average limitations in assimilable phosphorus and pH unlike the soil far from the station which presented an insufficiency of potassium which did not facilitate a balance cationic, a low CEC but a pH above 5.5 which is the value recommended in agronomy. Biochemically, organic matter is above 2% in all soils, a mineralization rate less than 20 favoring the rapid mineralization of carbon and a release of nitrogen available to the plant. These results obtained allow us to conclude that the sludge from the Yato station can be used in agronomy as an organic fertilizer in order to correct the soil structure, the CEC, the cationic balances and also provide the soil with a good base reserve. However, treating this sludge with lime could regulate the pH of the soil and reduce the mobility of heavy metals in the soil.