An effective method for the detoxification of cyanide-rich wastewater by Bacillus sp. CN-22

Abstract

The biodetoxification of cyanide-rich wastewater has become increasingly popular because of its cost-effectiveness and environmental friendliness. Therefore, we have developed an effective method, optimised by response surface methodology, for detoxifying cyanide-rich wastewater using Bacillus sp. CN-22, which was newly isolated from a cyanide-contaminated electroplating sludge and could tolerate a CN⁻ concentration of 700 mg L⁻¹. The concentration of CN⁻ in the treated wastewater decreased from 200 to 6.62 mg L⁻¹ after cultivation with 2.38 % inocula for 72 h on the medium, consisting of 0.05 % KH₂PO₄, 0.15 % K₂HPO₄, 1.0 mM MgCl₂, 1.0 mM FeCl₃, 0.1 % NH₄Cl, and 0.1 % glycerol. The CN⁻ degradability of 96.69 % is similar to the predicted value of 96.82 %. The optimal cultivation conditions were controlled as follows: initial pH, 10.3; temperature, 31 °C; and rotary speed, 193 rpm. The maintenance of higher pH in the overall treatment procedures may avoid the production of volatile HCN and the risk associated with cyanide detoxification. Additionally, the bacterial strain Bacillus sp. CN-22, with its potent cyanide-degrading activity at the initial CN⁻ concentration of 200 mg L⁻¹, may be employed to effectively treat cyanide-rich wastewater, especially electroplating effluent.

Biodegradation of free cyanide by bacterial species isolated from cyanide-contaminated artisanal gold mining catchment area in Burkina Faso

“…Temperature, pH and nutrient availability are the main parameters that control the efficiency of cyanide degradation (Kumar et al, 2013). The optimum temperature for cyanide degradation was usually around 30 C Chen et al, 2008;Huertas et al, 2010;Shete and Kapdnis, 2012;Wu et al, 2014). The rate of cyanide degradation is inversely related to temperature, when temperature is varied between 27 C and 50 C (Basile et al, 2008).…”

Removing cyanide by mixed culture at liquid media with variation in pH and cyanide concentration

“…Gold ore as a result containing sulphides and cyanide in a large quantities, so the volume of cyanide waste water that generated by jewelry industry usually contain high metal concentration. Cyanide was totally toxic and dangerous for organism and environment [2]. Cyanide can have a negative impact to human's health and animal that causing death, also environment pollution.…”

“…However, the adsorption process using Granular Activated Carbon (GAC) can damage the environment, highly cost and causing demage as a result from secondary pollution [5]. Bioremediation becomes one of the alternative methods to remove cyanide by utilizing the ability of microorganism or plants to convert the toxicated cyanide compounds into simple compounds [2,6,7]. Cyanide is converted into a source of carbon and nitrogen by various enzymes which exist in microorganisms [8].…”

Bioremediation of soil and water polluted by cyanide: A review

“…But, the chemical oxidation processes are more expensive and could to produce other hazard compounds (Sharma, 2012;Vidali, 2001). Therefore, most of researches focused on the biological processes for destroying the cyanide compounds (Akinpelu et al, 2015;Fernandez et al, 2004;Huertas et al, 2010;Mekuto et al, 2013;Yamasaki et al, 2002;Wu et al, 2014). Microorganisms and/or plants could be transform cyanide on compounds less toxic.…”