Bioremediation Of A Spent Metalworking Fluid With Auto- And Allochthonous Bacterial Consortia

Abstract

Spent mineral oil-based metalworking fluids are waste products of the machining processes and contribute substantially to the global industrial pollution with petroleum oil products. Wastewaters containing oily emulsions are ecologically hazardous and thus a variety of methods have been implemented to prevent these effluents from affecting the natural environment. Most of these methods rely upon physical-chemical treatment and phase separation; however, none of them proved to be effective enough to meet tightening environmental regulations. Therefore, novel technologies need to be elaborated and there is growing interest in implementing biological treatment methods based on microbial bioremediation. In this study an oil/water emulsion obtained from a waste stream of the metal-processing industry was tested for biodegradability of its organic constituents. This liquid waste was found non-toxic to bacterial consortia and was colonized with indigenous microorganisms (approx. 10 7 cfu · cm -3). The total load of organic content was determined as a chemical oxygen demand (COD) value of 48 200 mg O2 · dm -3. Emulsion treatment was carried out using a threefold wastewater dilution and employing two variants of biostimulated aerobic bacterial communities: (1) uninoculated emulsion, where bioremediation was carried out by the autochthonous bacteria alone, and (2) wastewater samples inoculated with a ZB-01 microbial consortium which served as a source of specialized bacteria for process bioaugmentation. Biodegradation efficiency achieved in a 14-day test was monitored by measuring both the COD parameter and the concentration of high-boiling organic compounds. Both approaches yielded satisfactory results showing significant reduction of the emulsion organic fraction; however, the resultant decrease of wastewater load tended to be more efficient for the case where the process was bioaugmented with the inoculated consortium. Gas chromatography analyses coupled with mass spectrometric detection (GC-MS) confirmed high degradation yields obtained for both cases studied (58 and 71%, respectively) in a 28-day test. It is concluded that oil-based metalworking emulsions can undergo efficient biological treatment under conditions enabling aerobic bacterial proliferation and that xenobiotic biodegradation kinetics can be accelerated by bioaugmenting the process with allochthonous microbial consortia.

Archives of Environmental Protection

“…ZB-01 contains strains of bacteria naturally occurring in the environment and specializing in the breakdown of organic pollutants. Their population decreases as petroleum products decompose, allowing to develop typical soil microflora (Kaszycki et al 2011). However, to check if there are any effects that may arise from the circulation of ZB-01 in the soil, also the unpolluted soil was treated by ZB-01.…”

“…ZB-01 biopreparation is a microbial preparation which has been widely used to initiate and stimulate biodegradation of petroleum-derived substances in contaminated waters and soils. We chose it because its usefulness in decomposition of petroleum-derived contaminants has been already confirmed by many studies (Petryszak et al 2008, Kaszycki et al 2010, Kaszycki et al 2011, Kaszycki et al 2015. Finally, we analyzed the relationships between Sitona spp.…”

Purification of Oil-Containing Waste Using Solar Energy

“…Study of biodegradability of organic constituents of the oil/water emulsion obtained from a metal-processing waste stream was carried out in paper [12]. The conducted study showed that oil/water emulsion is non-toxic to bacterial consortia, therefore it was colonized with indigenous microorganisms.…”

Minimization of the Negative Environmental Impact of Oil Sludge by Using it in the Production of Bitumen

“…Study of biodegradability of organic constituents of the oil/water emulsion obtained from a metal-processing waste stream was carried out in paper [29]. The conducted study showed that oil/water emulsion is non-toxic to bacterial consortia, therefore it was colonized with indigenous microorganisms.…”