Effects of coagulation and operational flux on the membrane performance of an inline coagulation/ultrafiltration process for water treatment

Effects of coagulation and operational flux on the membrane performance of an inline coagulation/ultrafiltration process for water treatment

Manousaridis, G.

Rietveld, L.C. (mentor)
Heijman, S.G.J. (mentor)
Chen, J.P. (mentor)
Lakerveld, R. (mentor)

Civil Engineering and Geosciences

Water Management

NUS-TUD Double Degree Programme in Hydraulic Engineering and Water Resources Management

2014-03-11

The objective of the study was to investigate the effects of coagulation and operational flux on the membrane performance of an inline coagulation/ultrafiltration process for water treatment in the lab. A two-phase optimisation approach was adopted in order to achieve stepwise performance improvement using raw water (taken from one of Singapore’s reservoirs) as a case study. “Phase I” focused on the simulation of the inline coagulation/UF process composed of coagulation in jar test followed by immediate filtration with 0.05um paper filter, while “Phase II” consisted of the operation of a bench scale hybrid inline coagulation/UF system equipped with a pressurized membrane module in laboratory. The main focus area for “Phase I” was the identification of optimum alternative coagulant among aluminium chlorohydrate (ACH), polyaluminum chloride (PACl) and ferric chloride (FeCl3) compared to aluminium sulphate (alum). “Phase II” supplementary applied the previous findings of the selected coagulant and dosage in order to optimise the membrane performance during operation of a bench scale hybrid inline coagulation/ultrafiltration system. The experiments in “Phase II” included runs at different fluxes in the range of 72-146L/m2/h, for the determination of the fouling behaviour in terms of transmembrane pressure (TMP), fouling tendency and specific flux (K). The critical operational flux values were also estimated which might help in the determination of a “sustainable flux” under the operating conditions investigated. It was found that for “Phase I” the optimum coagulant would be ACH in a dosage of 1.7mg (Al)/L, with a TOC removal efficiency (40%) comparable to alum (35-45%), good effluent turbidity and acceptable dissolved aluminium concentration <0.05mg/L without the need of pH pre-adjustment, while usage of lime for pH post-adjustment could be reduced. In “Phase II”, from the elaboration of the results under different fluxes, the critical flux (Jcs) was roughly estimated around 20 L/m2/h, for the threshold flux (Jthr) a range around 90-125 L/m2/h was selected, while for the critical flux for irreversibility (Jci) and the “sustainable flux” non-quantified suggestions were made. Regarding the operational parameters, even though an exact flux has not been clearly proposed, the alternative of 94 L/m2/h stood out as it resulted compared always with the flux of around 74 L/m2/h, to a 5% improvement in specific flux, 16% increase in the average TMP, while the fouling rate remained similar to lower fluxes at around 0.16bar/h with a backwashable component after 1.5h being at 70% and dropping to 65% for the first 3h. Recommendations for the final selection have been given as there are a plethora of subjective operational parameters that need to be taken into account.

coagulation
flux
optimisation

http://resolver.tudelft.nl/uuid:a0c99593-c27a-4d1a-8859-405b27f12e32

2019-03-11

Student theses

master thesis

(c) 2014 Manousaridis, G.