The Effect of Lime Treatment on the "Soluble" Organics in Domestic Wastewater

Abstract

<p>Gel Chromatography has been used in this study to investigate the effect of lime treatment on pure compounds and wastewater samples. Using pure compounds, it was found that porous glass gel, even after coating with carbowax, is unsuitable because of its adsorptive and ion exchange tendencies. With Sephadex gel, proteins and wastewater samples showed a strong dependence on sample inorganic content. While use of an ionic eluant provided consistent elution behavior with proteins and carbohydrates on Sephadex; best elution behavior with wastewater samples was obtained with distilled water eluant.</p> <p>Chemical treatment at high pH of pure compounds revealed that proteins and polysaccharides are not hydrolysed. However, ribonucleic acid is hydrolysed, and some proteins and humic acid can be precipitated from solution. Lime treatment of wastewater has indicated that the removal of "soluble" organics is highly pH and time dependent. Up to 40% organic removal was obtained by precipitation or adsorption mechanisms. Gel filtration analysis of these samples indicated that lime treatment at different pH levels and residence times has a selective effect on organic fractions. Optimum level for turbidity and phosphate removal with lime is roughly pH I I with greater than 80% removal achieved.</p>