Managing Nutrient Leaching Behavior in DC Water's Cambi Material

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DC Water’s Cambi biosolids material (CM) is formed from a new thermal hydrolysis procedure. CM nutrient leaching characteristics was examined employing 20 column studies and various leaching experiments. The materials were found to leach high concentrations of nitrogen, phosphorus, and potassium when tested with 10% and 15% CM (dry mass). The material was found to have a long-lasting leaching ability and to act differently when dry compared to wet. The dominant forms of nitrogen leaching were ammonium and organic N; the forms of phosphorus changed over time. Initially, organic P and particulate P leached and over time ortho-phosphate leached. Soil amendments for phosphorus and nitrogen mitigation were tested. Aluminum-based water treatment residuals (WTR) were found to be effective at decreasing phosphorus concentrations in the material leachate at ratios of 35%, 50%, and 75% WTR:CM. Results suggest this material to have long-term slow release benefits as a land application and organic fertilizer.