Liquid-Liquid Extraction of Trace Level Pesticides from Process Streams

摘要

The report describes the further resolution of the feasibility of a process (liquid-liquid extraction for the treatment of pesticide manufacturing wastewater) that had been shown by earlier research to be competitive with existing methods of treatment. Eight experiments were conducted using the Solvent Extraction of Organic Pesticides (SEXOP) process to treat process effluent samples of 2,4-D and bromacil. Process modifications designed to optimize the SEXOP system for treating these effluents were developed and tested. Gas chromatography was used to compare treated effluent with the untreated starting material. Pesticide extraction efficiencies were calculated: results show that pesticide removal in excess of 98% is attainable during initial operation, and 70% on a steady-state basis for a single-pass system for both samples tested. Staging of extraction units and increased solvent/water ratios would be expected to optimize steady-state efficiencies above 90%. An economic analysis, projecting engineering cost estimates for both a large and a small commercial-scale SEXOP process, shows that a projected large SEXOP plant should be able to process 301 million gal./yr of effluent at an estimated cost of about $2 per 1,000 gal.