THE ANALYSIS AND BEHAVIOR OF SLUDGE HUMIC MATERIAL

The primary objective of this research is to gain information concerning humic material from a sewage plant.; Sludge polymers were eluted from the sludge mass at different pH conditions. Their molecular weight distributions were monitored and compared with the aid of gel permeation chromatography. Only one molecular weight peak appeared at about or less than 200 when sludge was leached with distilled water. When sludge polymers were extracted at pH 3.5, one small peak, at a position corresponding to that excluded from Sephadex G-50 (i.e. Mwt (GREATERTHEQ) 30,000), and/or one small peak at the intermediate molecular weight of 8,000 were observed. The bulky material of acid extracted sludge polymers was eluted in the molecular weight range of 1,000 to 30,000. The alkali-extracted polymers gave a molecular weight distribution covering the entire fractionation range of Sephadex G-50 with two peaks at high and low elution volumes.; The high molecular weight components of sludge humic-like matter (alkali-extracted polymers) excluded from Sephadex G-50 were less removed by carbon but effectively reduced by clay.; The absorption rate of sludge humic-like material on clay and activated carbon indicated that a steady state was reached within 20 minutes. The clay, diatomite and activated carbon adsorption sequence could remove up to 95% of the color along with 81% of COD. The color of the final treated effluent could not be visibly detected. The less colored and/or uncolored COD (organic matter) were less susceptible to adsorption. Diatomite had a very low sorption capacity for sludge humic-like material.; The mechanisms of humic adsorption on clay and carbon were pursued using commercial humic acids. The ratio of adsorption at 465 nm to that at 665 nm decreased after treatment with activated carbon. A relation between ratio values and carbon doses was observed.; Both the Freundlich and the Langmuir isotherm plots for kaolin clay adsorption of humic acid showed curvilinearity. Each was resolved into two straight lines and their regression lines were computed. The maximum adsorption obtained from the Langmuir equation was 1.35 mg COD/g at pH 7.2.; The adsorption of humic acid covering an equilibrium concentration range up to 54 mg COD/1 on granular activated carbon was investigated. A linear sorption isotherm was found over an equilibrium concentration from 1 to 17 mg COD/1. At higher concentration, the Freundlich and the Langmuir plots exhibited similar curvilinearity to that of kaolin adsorption, suggesting that humic acid consists of two main populations--i.e., one easily adsorbable material and the other less adsorbable material. Their distribution was computed based on the Freundlich isotherm for carbon sorption and about 56% of the humic acid components were found to be easily adsorbable material. The nonadsorbable residuals at pH 7.7 were found to be 4.37 mg COD/1. The maximum adsorption by one gram of carbon was found to be 11.81 mg COD.; Humic and fulvic acids were extracted from sludge and further fractionated on Sephadex G-50. They constituted about 28% of sludge COD. Sludge humic acid was less condensed as compared to soil humic acid.; The infrared spectra of sludge humic and fulvic acids were similar to those of aquatic humic material reported elsewhere, featured with the strong absorption at 1540 and 1050 cm('-1) due to protein and polysaccharide, respectively.; The result of ('1)H-NMR spectra showed that sludge fulvic acid was more aliphatic and less aromatic; its constituents contained degradation products of polysaccharide and protein.