Application of immobilized cells to the treatment of cyanide wastewater

Abstract

Cyanide is highly toxic to living organisms, particularly in inactivating the respiration system by tightly binding to terminal oxidase. To protect the environment and water bodies, wastewater containing cyanide must be treated before discharging into the environment. Biological treatment is a cost-effective and environmentally acceptable method for cyanide removal compared with the other techniques currently in use. Klebsiella oxytoca (K. oxytoca), isolated from cyanide-containing industrial wastewater, has been shown to be able to biodegrade cyanide to non-toxic end products. The technology of immobilized cells can be applied in biological treatment to enhance the efficiency and effectiveness of biodegradation. In this study, potassium cyanide (KCN) was used as the target compound and both alginate (AL) and cellulose triacetate (CTA) techniques were applied for the preparation of immobilized cells. Results from this study show that KCN can be utilized as the sole nitrogen source by K. oxytoca. The free suspension systems reveal that the cell viability was highly affected by initial KCN concentration, pH, and temperature. Results show that immobilized cell systems could tolerate a higher level of KCN concentration and wider ranges of pH and temperature, especially in the system with CTA gel beads. Results show that a longer incubation period was required for KCN degradation using immobilized cells compared to the free suspended systems. This might be due to internal mass transfer limitations. Results also indicate that immobilized systems can support a higher biomass concentration. Complete KCN degradation was observed after the operation of four consecutive degradation experiments with the same batch of immobilized cells. This suggests that the activity of the immobilized cells can be maintained and KCN can be used as the nitrogen source throughout KCN degradation experiments. Results reveal that the application of immobilized cells of K. oxytoca is advantageous to the maintenance of KCN degradation efficiency. Thus, it is conceivable that the immobilized cells of K. oxytoca would be applicable to the treatment of cyanide-containing wastewaters.

Evaluating the potential of immobilized bacterial consortium for black liquor biodegradation

“…This phenomenon has also been reported in previous studies but with single culture (Brányik et al 2004;Yu et al 2010;Genisheva et al 2011). Previous studies have revealed that immobilization technology is advantageous in maintaining the degradation efficiency of cells for wastewater treatment (Chen et al 2007;Chen et al 2008;Pakshirajan and Swaminathan 2009;Xu et al 2012). However, utilization of agro-industrial residue for cell immobilization have mostly done to enhance the fermentation process or to study oenology.…”

Performance Of Immobilized-Selected Microorganisms In The Biodegradation Of Textile Industry Waste Water

“…The other advantages of using immobilized cells reported some researchers are no obvious loss of cell activity was observed over the four consecutive uses of the immobilized cells (Chen et al, 2007). Murakami-nitta et al(2003) also reported that the number of viable cells increased after reuse.…”

“…Some researchers reported that immobilized cells are able to tolerate the change in pH of medium than free cells (Linardi, 2001;Nigam, 2000). Chen et al(2007) reported pH would have a significat on microbial activities and a neutral environment is suggested to obtain higher pollutant degradation rate with immobilized cells. Thus, in this research the immobilized cells were incubated untill pH reached on the neutral range to anticipate stress of cells because wastewater pH used in the experiment were higher than 6.5.…”

“…In this research, pH of wastewater were 8 to 8.5 indication of alkali condition and reactors were operated at room temperature. According to Chen et al (2007), if the ambient is higher than the optimal temperature, thermal death of the cells might occur, and removal rates would decrease. However, Murakami-nitta et al(2003) observed that a free cell system was more sensitive to temperature change than immobilized cells, and immobilization increased the thermal stability of the cells.…”

“…As Reported by researcher, the use of native biomass (such as bacteria, yeast fungi and algae) for degradation pollutant in freely suspended state has a limitation, owing to their inherent disadvantages such as small particle size, possible clogging, and washed out potentially (Mostafa et al, 2015). Free supension cells also could not tolerate the toxicity pollutant at high levels (Chen et al, 2007;Godjevargova et al, 2004).…”