Treatment of cyanide-containing wastewater from the food industry in a laboratory-scale fixed-bed methanogenic reactor

Applied Microbiology and Biotechnology
H Siller, J Winter

Abstract

During the process of producing cassava starch from Manihot esculenta roots, large amounts of cyanoglycosides were released, which rapidly decayed to CN- following enzymatic hydrolysis. Depending on the varying cyanoglycoside content of the cassava varieties, the cyanide concentration in the wastewater was as high as 200 mg/l. To simulate anaerobic stabilization, a wastewater with a chemical oxygen demand (COD) of about 20 g/l was prepared from cassava roots and was fermented in a fixed-bed methanogenic reactor. The start-up phase for a 99% degradation of low concentrations of cyanide (10 mg/l) required about 6 months. After establishment of the biofilm, a cyanide concentration of up to 150 mg CN-/l in the fresh wastewater was degraded during anaerobic treatment at a hydraulic retention time of 3 days. All nitrogen from the degraded cyanide was converted to organic nitrogen by the biomass of the effluent. The cyanide-degrading biocoenosis of the anaerobic reactor could tolerate shock concentrations of cyanide up to 240 mg CN-/l for a short time. Up to 5 mmol/l NH4Cl (i.e. 70 mg N/l = 265 mg NH4Cl/l) in the fresh wastewater did not affect cyanide degradation. The bleaching agent sulphite, however, had a negative effect on COD an...Continue Reading

Citations

Oct 20, 2005·Journal of Bioscience and Bioengineering·M D Adjei, Y Ohta
Dec 20, 2012·Environmental Science & Technology·Paula OulegoMario Diaz
Dec 7, 2017·Applied Microbiology and Biotechnology·Víctor M Luque-AlmagroMaría Dolores Roldán
Nov 19, 2020·Preparative Biochemistry & Biotechnology·Adedeji Nelson AdemakinwaOladapo Fagbohun

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