Dimuth Navaratna

Treatment of textile wastewater with membrane bioreactor: a critical review

Membrane bioreactor (MBR) technology has been used widely for various industrial wastewater treatments due to its distinct advantages over conventional bioreactors. Treatment of textile wastewater using MBR has been investigated as a simple, reliable and cost-effective process with a significant removal of contaminants. However, a major drawback in the operation of MBR is membrane fouling, which leads to the decline in permeate flux and therefore requires membrane cleaning. This eventually decreases the lifespan of the membrane. In this paper, the application of aerobic and anaerobic MBR for textile wastewater treatment as well as fouling and control of fouling in MBR processes have been reviewed. It has been found that long sludge retention time increases the degradation of pollutants by allowing slow growing microorganisms to establish but also contributes to membrane fouling. Further research aspects of MBR for textile wastewater treatment are also considered for sustainable operations of the process.

Performance of a laboratory-scale membrane bioreactor consisting mixed liquor with aquatic worms under toxic conditions.

A laboratory scale membrane bioreactor (MBR) consisting of worms was operated for 214days. The objective was to evaluate the treatment and operating performance of the MBR with and without the addition of Ametryn which is a toxic and persistent herbicide. Removal of Ametryn was doubled (up to 80%) in the MBR when the worms were present. Increased rate (2.5kPa/day) of trans-membrane pressure (TMP) and low concentration of MLSS (5.5g/L) were recorded when the worm population was high (80-100 worms per 70μL). Short-term critical flux values were increased from 7.5 to 15 and then to 30L/m(2)/h when the worm numbers decreased from 90 to 35 and then to 18 per 70μL of mixed liquor respectively. Further, high levels of carbohydrate concentration of soluble microbial products (SMP) and smaller sludge floc-sizes were found when the worm numbers were high.

Evaluation of herbicide (persistent pollutant) removal mechanisms through hybrid membrane bioreactors

A laboratory-scale membrane bioreactor (MBR) combined with ultraviolet (UV) disinfection and granular activated carbon (GAC) adsorption was researched for over seven months to evaluate the removal efficiencies and mechanisms of a moderately persistent s-triazine herbicide (Ametryn), which is commonly used in Australian sugarcane farmlands. Long-term experiments showed that MBR alone (15h hydraulic retention time (HRT)) can remove 65% of Ametryn from its influent which had a concentration of 1-2mg/L. A batch study was carried out to assess the mechanisms of removal of Ametryn through MBR and found that 0.1186mg of Ametryn/g-VSS is adsorbed onto sludge particles when 1mg/L of Ametryn is added to the mixed liquor and showed a 64% removal after 12h. This experiment confirmed that 99%, 92% and 83% removal of Ametryn could be achieved only from biodegradation, if the MBR maintains a HRT of 7.5, 2.5 and 1.5days respectively.

A methodology for simulating hydrogen sulphide generation in sewer network using EPA SWMM

AbstractPredicting hydrogen sulphide concentration in sewer network through modelling tools will be beneficial for many stakeholders to design appropriate mitigation strategies. However, the hydrogen sulphide modelling in a sewer network is crucially dependent on the hydraulic modelling of the sewer. The establishment of precise hydrogen sulphide and hydraulic modelling however requires detailed and accurate information about the sewer network structure and the model parameters. This paper outlines a novel approach for the development of hydraulic and hydrogen sulphide modelling to predict the concentration of hydrogen sulphide in sewer network. The approach combines the calculation of wastewater generation and implementation of flow routing on the EPA SWMM 5.0 platform to allow hydrodynamic simulations. Dynamic wave routing is used for hydraulic simulations. It is considered to be the best approach to route existing/old sewer flow. The build-up of hydrogen sulphide model includes the empirical models of ...