The Role of Inorganic Metal Salts in Wastewater Clarification

Abstract

An investigation into the ability of four inorganic coagulants namely; alum (Al2(SO4)3.18H2O), ammonium aluminum sulphate (NH4Al(SO4)2.12H2O), ferrous sulphate (FeSO4) and ammonium ferrous sulphate (NH4)2Fe(SO4)2.6H2O) in clarifying wastewater was examined. Results obtained from conventional standard ‘jar-test’ experiments indicated that alum was the most effective coagulant since it reduced turbidity of the wastewater to 0.64 NTU at a contact time of 300 min. Ferrous sulphate was the least effective coagulant, reducing turbidity of the wastewater to 3.45 NTU only at 240 min contact time, but when the contact time of the experiment was increased from 240 to 300 min, re-coloration of the solution was observed indicating re-stabilization of suspended particles. These findings tend to support the claim that alum is a choice coagulant for wastewater clarification.

Phosphorus in Balance: Evaluating the Costs and Benefits of a Circular Economy Approach

“…Costs to produce 1 ton of alternative P fertilizer. 2 Various chemicals like iron trichloride, iron sulfate, aluminum sulfate, and calcium chloride can clarify wastewater but may unintentionally remove P, which is needed for adsorption (Ukiwe et al 2013). However, the nanocomposite material 3% N/C 24 (an industrial material manufactured at the GES Your water treatment expert factory, Israel), used in this study, exclusively removes total suspended solids (TSS) while preserving nutrients like P. Physical methods like centrifugation are also available but yield low TSS removal, impacting P adsorption quality.…”