Characterisation of FOGs in grease trap waste from the processing of chickens in Thailand

Industrial firms that kill and process chickens generate wastewater that contains fat, oil, and grease (FOG). The FOGs are located in the fatty waste that is collected by floatation in grease traps. Chemical and physical characterisation of FOGs would provide useful information that would help in the development of methods designed to decrease the extent of pollution caused by disposal of the waste and to utilise commercially some of its lipid constituents. Employing these methods would enhance the profitability and competitive potential of these commercial organisations. Samples of grease trap waste from 14 firms in central Thailand have been examined. Due to the very different schemes of waste management employed by these firms, the physical appearance of their fatty wastes showed considerable variation. The chemical and physical properties of the FOGs present in these wastes showed considerable variation also. Large amounts of free fatty acids (10–70% as oleic acid) were detected in most of the 14 wastes and palmitic, cis-9-oleic, cis,cis-9,12-linoleic, stearic, and palmitoleic acids were the predominant species of free and esterified acids. Most of the FOGs were solid at temperatures below 40 °C. Many of them contained traces of heavy metals (Cu and Pb) and some contained traces of the pesticides dimethoate and cypermethrin. The content of these potentially hazardous substances would have to be considered very carefully before discarding the fatty wastes and during the development of methods designed to isolate their potentially profitable lipid constituents.     

Enhanced fat degradation following the addition of a Pseudomonas species to a bioaugmentation product used in grease traps

The presence of fats, oils and greases (FOGs) in wastewater can lead to many problems including blockages. Investigation of a bioaugmentation product, consisting of Bacillus spp., to degrade butter (1%, W/V) and olive oil (1%, V/V) was performed in aerobic batch cultures for 13-day incubation. Gravimetric analysis of the remaining substrates showed slowly degradation of the oil after a 2-day lag, but no degradation of the butter. Addition of a Pseudomonas putida strain CP1 to the Bacillus spp. population promoted rapidly degradation of both fats after 7?days of incubation. High fat accumulation revealed the potential use of the new bacterial mixture for production of added-value compounds. Lipase production only by the Bacillus spp. along with the analysis of the remaining lipids with thin layer chromatography and gas chromatography, suggested that the Bacillus spp. mainly only hydrolyzed the fat. The breakdown products were metabolized by the Pseudomonas putida CP1 performing preferential utilization of unsaturated fatty acids. Investigation of population dynamics using selective plating and a labeled Pseudomonas putida CP1::Tn7-gfp showed domination of the latter. The new mixture performed a successful cooperation with good potential for FOG treatment and an aggregative response desirable to fat degradation in grease traps.