Improving Soil Fertility and Nutrient Dynamics with Leachate Attributes from Sewage Sludge by Impoundment and Co-Composting

摘要

Co-composting offers a sustainable solution for community level sewage treatment plants (STP) by producing nutrient-optimized compost. Soils in such treatment vicinity are susceptible for receiving significant quantity of wastewater, capable of causing a radical shift in soil structure and nutrient dynamics. Samples of sludge-leachate impounded soil (SLIS) and low fertile soil are collected to select the proportioning of sludge-derived composts (SDC). A series of batch experiments are conducted by mixing pre-determined quantity of SDC with field soils on weight basis to identify the best proportioning combination. Based on the in-vessel aerobic cocomposting experiments with reuse of generated leachate (at a rate of 1.0 per week), SDC exhibits good nutrient stability in terms of carbon-nitrogen ratio (8-11) with effective moisture augmentation from leachate (45%-74%) under non-isothermal conditions (between 46 +/- 2 degrees C and 32 +/- 4 degrees C) within 45 days of incubation. Significant nitrogen transformation is exhibited in SLIS samples due to the temporal variations in sludge decomposition as verified through leaching column experiments. Approximately 30% of nutrient (carbon and nitrogen) leaching is prevented due to the improved moisture retention capacity in presence of compost. An empirical correlation has been derived between various analytical measures of organic matter depicting enhanced decomposition stages of sludge in soil amendments.