Water Science & Technology Vol 66 No 6 pp 1289–1295 © IWA Publishing 2012 doi:10.2166/wst.2012.315

MBR fouling control and permeate quality enhancement by polyaluminium chloride dosage: a case study

A. Teli, M. Antonelli, L. Bonomo and F. Malpei

Scope of this study was to evaluate the effectiveness of a metal salt (polyaluminium chloride, PACl) dosage into a pilot-scale MBR (membrane bioreactor) in terms of fouling control and permeate quality enhancement, especially with reference to specific textile macro-pollutants (dyes and surfactants). The pilot plant was fed with a mixed domestic-textile wastewater (textile wastewater accounted for 65% of total flow and for 70% of total chemical oxygen demand, COD, load) and operated for 7.5 months without flux enhancers (step 1) and 3 months with the addition of PACl (step 2). The optimum dose was defined performing a jar-test campaign between step 1 and step 2 (12.5 mg gMLSS⁻¹ that corresponds to 0.4 g d⁻¹). The addition of PACl resulted in a significant decrease of the filtration resistance due to cake layer formation (R_c, −65.4%) and of the irreversible fouling rate, evaluated as the average variation per unit time of the filtration resistance due to foulants adsorption on membrane pore wall (FR, −45.3%). As for permeate quality, removal rates related to total phosphorus and textile macro-parameters such as colour and anionic surfactants, increased by +64, +16 and +7%, respectively. No significant effect was observed on COD, non-ionic surfactants and nitrogen compounds removal.

Keywords: flux enhancers; fouling; membrane bioreactor; polyaluminium chloride

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