Algal control and enhanced removal in drinking waters in Cairo, Egypt

Abstract

Algal blooms at the major water treatment plants in Egypt have been reported since 2006. While previous studies focused on algal types and their correlation with disinfection by-products, correlation between raw water quality and algal blooms were not explored. Therefore, a survey of Nile water quality parameters at a major water intake in the Greater Cairo Urban Region was conducted from December 2011 to November 2012. Bench-scale experiments were conducted to evaluate the effectiveness of the conventional chloride/alum treatment compared with combined Cl/permanganate pre-oxidation with Al and Fe coagulants during the outbreak period. Addition of permanganate (0.5 mg/L) significantly reduced the chlorine demand from 5.5 to 2.7 mg/L. The applied alum coagulant dose was slightly reduced while residual Al was reduced by 27% and the algal count by 50% in the final treated waters. Applying ferric chloride and ferric sulfate as coagulants to waters treated with the combined pre-oxidation procedure effectively reduced algal count by 60% and better the total organic carbon reduction and residual aluminum in the treated water. Multivariate statistical analysis was used to identify the relationship between water quality parameters and occurrence of algae and to explain the impact of coagulants on the final water quality.

Clarification of algae-laden water using electrochemical processes

“…While these problems can be solved by centralized water treatment and distribution systems, this approach is not practical for most rural areas, which lack both the infrastructure and capital to build and support such systems (Mollah et al, 2004). In rural areas, algal growth due to eutrophication is a major contributor to water contamination (Shen et al, 2011;El-Dars et al, 2015) and an efficient way to remove algae would be an important step in the direction of improving water quality.…”

The Use of TiO2 as a Disinfectant in Water Sanitation Applications

“…Another assay, using a similar chlorination application, augmented with Al and Fe on algae from a wastewater treatment plant. Assays made by [87] achieved removals of up to 60%. Studies on algae removal are scarce and show heterogeneous efficiencies when using conventional disinfectants.…”