PHYSICOCHEMICAL CHARACTERISTICS OF A NEW ORGANIC SOIL CONDITIONER FROM COMPOSTED SLUDGES FROM A PULP DEINKING PROCESS

A new organic soil-conditioner from composted sludge produced from a n ewspaper deinking process was examined compared with raw uncomposted s ludge, its physical and chemical characteristics tested in order to st udy its effectiveness. The water-holding capacity of the conditioner w as almost 7.6 and 1.8 times higher than that of the pure soil and the raw sludge, respectively, and remained stable at temperatures between 9 degrees C and 27 degrees C. The composted sludge had a 53% organic m atter content and 35% in humic substances which was 3.5 and 2.0 times lighter than the pure soil and the raw sludge. Incorporation of this m aterial into the soil in concentrations of up to 25% resulted in a 1.7 times increase of the water-holding capacity of the mixture, whereas 90% of the water-holding capacity was achieved in less than 10 min. Th e apparent density of the mixture was decreased and was not affected b y the residence time of the samples into the water. The pH of the mixt ure's eluates was shifted to higher values (pH=7.0). The specific cond uctivity of the eluates was increased. Due to this parameter, a limit was observed in the use of this conditioner. The amount of ammonium-ni trogen (NH -N), phosphorus (P), calcium (Ca), magnesium (Mg), zinc (Zn ), copper (Cu)(4), and manganese (Mn) in the eluates increased, while the amount of potassium (K) and iron (Fe) decreased in comparison to w hat would be expected from the separate contributions of soil and cond itioner. Therefore, there exists an interaction between this material and soil that occurs when the conditioner is incorporated into soil.