Toxicity and Removal of Phenol by a Land Treatment System

Abstract

To study the toxicity and removal of phenol by a land treatment system, two phases of lab-scale experiments were conducted under ambient conditions using two soil columns filled with a sandy loam soil. Phase I was conducted to investigate the toxic effects of phenol on the soil microbes in utilizing of a synthetic wastewater (200 mgCOD l−1 of glucose). The soil columns, operating at the liquid loading of 5 cm wk−1, were found to effectively treat the synthetic wastewater containing 10–100 mg l−1 of phenol. The added phenol had no toxic effects on the soil microbes, but was utilized by the soil microbes as a carbon source. Phase II was conducted to investigate the performance of the soil columns in treating a synthetic phenol wastewater and its removal kinetics. The influent phenol concentrations were varied at 200, 300, 500, and 800 mg l−1, while the liquid loading rates were varied at 5 and 10 cm wk−1. At the liquid loading rate of 10 cm wk−1, the biokinetic constants (Ki, Ks, μm) involved in the Haldane equation were found, respectively, to be 163.93 mg l−1, 29.09 mg l−1 and 3.52 day−1, while the data of 5 cm/wk gave negative values of the biokinetic constants. The influent phenol concentration of upto 200 mg l−1 exhibited no toxic effects to the soil microbes. The higher the influent phenol concentrations above 200 mg l−1, the more the toxic effects on the soil microbes or the reduction of the phenol removal efficiencies. The phenol assimilative capacity of the sandy loam soil was found to be 11030 kg ha−1 yr−1.