Agricultural use of organic wastes stabilized with fluidized-bed combustion solid residues.

摘要

Alkaline stabilization has been increasingly recognized as a promising alternative for sewage sludge management. Chemicals are used in wastewater slurries processing for odor control, pH modification, pasteurization, disinfection, and stabilization. Lime and chlorine are the primary chemicals that have been extensively used for these purposes.; Fluidized bed combustion (FBC) is an emerging technology that reduces SO{dollar}rmsb{lcub}x{rcub}{dollar} and NO{dollar}rmsb{lcub}x{rcub}{dollar} emissions produced when coal is burned for the production of electricity. It operates with a limestone bed that is calcinated, forming a porous surface that captures the sulfur liberated during the reaction. The product is particulate matter, commonly known as fly ash, with large amounts of lime.; In this study, the effectiveness of alkaline stabilization process was tested by evaluating three mixtures at different ratios (on a wet basis) of FBC fly ash to sewage sludge. The fly ash was provided by Alternative Energy System (AES-P.R.) from their coal plants in Hawaii and Oklahoma. The sewage sludge was obtained from the Las Marias Wastewater Treatment Plant in P.R. Three specific conditions must be met to accomplish a beneficial product; temperature between 52-62{dollar}spcirc{dollar}C for 12 hours, pH over 12 for three days, and solid contents {dollar}>{dollar}50% by weight. Properties such as: pH, ash content, organic content, water content, bulk density, salinity, and alkalinity were determined by obtaining values very similar to those in the literature. The alkaline-stabilized product proved effective as fecal coliform counts decrease to negligible levels.; Metal content was below the pollutant concentrations regulated by the USEPA. NH{dollar}sb4sp+{dollar} and NO{dollar}sb3sp-{dollar} determinations resulted in acceptable values. The resulting mixture has a soil-like consistency, making it spreadable. The mixture at a ratio of 1:1 has both the nutrients benefits of sewage sludge as a fertilizer or soil conditioner, and the alkalinity for treatment. (Abstract shortened by UMI.)