Mulch tower treatment system Part I: Overall performance in greywater treatment
Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown, 6140, South Africa; Institute for Water Research, Rhodes University, Grahamstown, 6140, South Africa; Department of Environmental Science, Rhodes University, Grahamstown, 6140, South Africa
A mulch tower (MT) system for greywater treatment is introduced in this paper. Materials used to assemble the MT system included mulch, coarse sand, fine and coarse gravel. Limited removal efficiency of the MT system was demonstrated for alkalinity, total hardness, pH, Cl-, PO43-, NH4+, and SO42-, with the estimated cumulative removals ranging from 7 to 12%. Intermediate removal efficiency was observed for chemical oxygen demand (COD), NO3-, and S2- with the estimated cumulative removals ranging from 24 to 28%. The highest removal efficiency was observed for the total suspended solids (TSS) with the estimated cumulative removal equal to 52%. Given the minute residence time in the MT system, the results obtained were promising and justify scale-up studies for potential on-site applications. The MT effluent did not meet hygienic norms with respect to the faecal coliform concentration (FC) and the total coliform concentration (TC), and further effluent treatment is required before any discharge or reuse of the treated greywater. Further research should focus on characterisation of the microbial community of the MT, and the fate of Cl-, PO43-, NH4+, and SO42-. © 2008 Elsevier B.V. All rights reserved.
Characterisation; Chemical-oxygen demands; Coarse gravels; Coliform concentrations; Greywater; Greywater treatments; Microbial communities; Mulch tower; On-site treatment; Removal efficiencies; Residence time; Scale-Up; Site applications; Total suspended solids; Treatment systems; Alkalinity; Buildings; Chemical oxygen demand; Effluent treatment; Effluents; Oxygen; Range finding; Removal; Telluric prospecting; Towers; Wastewater treatment; Water recycling; chemical oxygen demand; estimation method; fecal coliform; microbial community; mulch; removal experiment