Comparison of the effect of two support materials on copper removal from aqueous solution in the activated sludge process

Abstract

Two support materials, microwave incinerated rice husk ash (MIRHA) and groundwater treatment plant sludge (GWTPS), were used as support materials for biomass in the removal of copper from aqueous solution during a continuous flow study. A third reactor containing biomass alone without the addition of support material (RB) was used as a control to monitor the performance of the support materials. All reactors were given 15 days for the acclimatization of biomass. The reactors containing MIRHA and GWTPS were given an additional 10 days for acclimation after the addition of the support materials on day 15. All reactors were identically designed with a size of 8.5 L and operated at a flowrate of 7 L/d and SRT of 30 days across 8 different phases. Different concentrations of Cu(II) ranging from 0.5 mg/L to 15 mg/L were applied to the reactors at different phases. Results obtained from each phase of the experiments showed that GWTPS and MIRHA improved copper toxicity resistance in their respective reactors. For the control reactor (RB), copper toxicity was significant and violated the DOE Malaysia copper effluent standard at phase 5 (influent concentration 2 mg/L) whereas MIRHA and GWTPS reactors violated the DOE Malaysia copper effluent standard at phase 7 (influent concentration 10 mg/L) respectively. However, GWTPS containing reactor showed slightly better support for toxicity resistance than reactor MIRHA. The toxicity of copper on the three reactors was observed in the reduction of mixed liquor volatile suspended solids (MLVSS) within each reactor. For the control, MLVSS rapidly decreased from phase 3 to phase 8 whereas MIRHA and GWTPS reactors increased from phase 3 to phase 6 and decreased from phase 7 to phase 8. These results have shown that MIRHA and GWTPS have the potential of improving biomass resistance to toxicity of heavy metals.

Bio-physical removal of heavy metal from aqueous solution

“…Thus, from phase 5 to phase 8, the suspended growth bioreactor was inhibited by toxicity and a relative decrease in the growth rate (MLVSS) was observed. Similar observation was made elsewhere [13]. As the MLVSS concentration decreases in the suspended growth bioreactor, Zn 2+ removal efficiency decreased and the effluent concentration increased.…”

“…In order to overcome this constraint and at relatively low-cost, low-cost physical processes have been adopted as a means to enhance microbial tolerance and resistance toward heavy metal toxicity and inhibition. The addition of powdered activated carbon derived from agricultural waste and solid waste materials in biological treatment processes have been explored but the application of precursors such as microwave incinerated rice husk ash [12] and groundwater treatment plant sludge (GWTPS) in biological treatment process are still at infancy [13,14]. In addition to their beneficial use in biological processes, it is also a waste minimization approach.…”

Optimization of methylene blue biosorption and mass transfer resistance on Gardenia carinata activated carbon

“…Due to the cost of industrial ACs, attention was directed to obtaining AC from solid and lignocellulosic waste from agriculture. Agricultural waste such as sugar cane bagasse [9,10], peanut husk [11], peanut hull [12], bamboo [13], coconut shell [14], empty fruit bunch [15] and rice husk [16][17][18] are suitable AC resources. The capacity of several un-modified adsorbents such as gulmohar plant leaf powder [19], ageratum conyzoide leaf powder [20,21] and neem leaf powder [22] has also been investigated.…”