Efficiency of aerobic biodegradation of beet molasses vinasse under non-controlled pH: conditions for betaine removal / Efektywność tlenowej biodegradacji buraczanego wywaru melasowego przy nieregulowanym pH podłoża: określenie warunków usunięcia betainy

Abstract

Abstract:The aim of the study was to establish such conditions that would provide high-effi ciency aerobic biodegradation of beet molasses vinasse with a mixed culture of thermo-and mesophilic bacteria of the genus Bacillus in batch processes without controlling the pH of the medium. Particular consideration was given to the betaine removal (the main pollutant of vinasse), which accounted for as much as 37.6% of total organic carbon. Biodegradation was performed in a stirred tank reactor at 27-63°C with initial pH (pH 0 ) of 6.5 and 8.0. Effi ciency of biodegradation was expressed in terms of reduction in SCOD sum , which is a sum of SCOD (soluble chemical oxygen demand, i.e. COD determined after suspended solids separation) and theoretical COD of betaine. The values achieved at 27 and 36°C with pH 0 = 8.0 exceeded 77.7%, whereas those obtained at 36 and 45°C with pH 0 = 6.5 were higher than 83.6%. The high biodegradation effi ciency obtained in the four processes is attributable to the betaine removal by the bacterial strains used in the study. Maximal extent of reduction in SCOD sum (85.41%), BOD 5 (97.91%) and TOC (86.32%), and also the fastest rate of biodegradation (1.17 g O 2 /l•h) was achieved at 36°C and pH 0 = 8.0.

Continuous Biodegradation of Sugar Beet Distillery Stillage in an Aerobic Stirred-Tank Reactor: The Effect of Hydraulic Retention Time

“…Biodegradation of this stillage conducted in the batch system under the same conditions, comparable HRT and the same bacterial culture as in our study resulted in very similar reductions of COD, BOD 5 and TOC, accounting for 80%, 98% and 76%, respectively, and in a similar value of the COD removal rate reaching 0.4 g O 2 /(L h) [2]. Efficiency of the continuous process approximated efficiencies of other analogous batch processes of biodegradation of such distillery wastewaters like: sugar beet molasses vinasse [16,26], corn stillage [32] and potato stillage [33]. The maximal COD reduction reported by these authors ranged from 74% (corn stillage) to 89% (potato stillage).…”

“…It contained two strains from B. circulans species and one strain from each of the following species: B. laterosporus, B. filicolonicus, B. stearothermophilus, B. acidocaldarius, and B. licheniformis. The method for the diagnosis of bacterial strains was described in our previous work [16]. Before the bacterial culture had been used in the study, its activity was maintained in an aerobic bioreactor without mixing, having a working volume of 0.5 L, aerated at the rate of 1.0 L/(L•min) and placed in an incubator at a temp.…”

“…Literature data indicates aerobic processesperceived by some authors as eco-friendly [10] -to be characterized by low sensitivity to a high contaminant load of distillery stillage [16]. Effective aerobic biodegradation of this effluent is usually achieved with a mixed culture of thermo-and mesophilic Bacillus bacteria [17,18].…”

“…Effective aerobic biodegradation of this effluent is usually achieved with a mixed culture of thermo-and mesophilic Bacillus bacteria [17,18]. They have the ability to assimilate the main components of the stillage (betaine, reducing substances, organic acids, glycerol) [2] as well as coloured substances (alkaline products of invert sugar degradation, products of saccharose carmelization and melanoidins) [16,19]. Moreover, Bacillus bacteria sp.…”

Archives of Environmental Protection

“…Sugar beet molasses vinasse (BMV) is a byproduct of processing molasses for ethanol. Its characteristic feature, in addition to the high loads of organic pollutions expressed by the chemical and biological oxygen demand, is a low pH and a dark brown color (Ryznar--Luty et al 2015, Wilk et al 2019. Melanoidins, caramel compounds and hexoses alkaline degradation products (HADP) contribute to the intense color of the vinasse and have a huge infl uence on the degree of its pollution and toxicity (Agnihotri 2015, Arimi et al 2014, Chowdhary et al 2018.…”