Enhancing anaerobic digestion performance of crude lipid in food waste by enzymatic pretreatment

Abstract

Three lipases were applied to hydrolyze the floatable grease (FG) in the food waste for eliminating FG inhibition and enhancing digestion performance in anaerobic process. Lipase-I, Lipase-II, and Lipase-III obtained from different sources were used. Animal fat (AF) and vegetable oil (VO) are major crude lipids in Chinese food waste, therefore, applied as substrates for anaerobic digestion tests. The results showed that Lipase-I and Lipase-II were capable of obviously releasing long chain fatty acid in AF, VO, and FG when hydrolyzed in the conditions of 24h, 1000-1500μL and 40-50°C. Compared to the untreated controls, the biomethane production rate were increased by 80.8-157.7%, 26.9-53.8%, and 37.0-40.7% for AF, VO, and FG, respectively, and the digestion time was shortened by 10-40d. The finding suggests that pretreating lipids with appropriate lipase could be one of effective methods for enhancing anaerobic digestion of food waste rich in crude lipid.

Bio-Delipidation of Dissolved Air Flotation Pre-Treated Poultry Slaughterhouse Wastewater

“…Subsequent to bio-delipidation, these findings were also confirmed by visual inspection of the tubes, which showed less turbid characteristics for the bio-delipidized samples. [7] and [2] also observed similar results, where the application of lipase enzyme in fatty wastewater reduced turbidity. In this study, the comparative analysis for total protein concentration of DAF pre-treated PSW and bio-delipidized samples was necessary because proteins are huge contributors to pollution and are prevalent in PSW [23].…”

“…Furthermore, clogging of pipe systems due to the building up of FOG leads to process redundancies. In certain instances, solidified lipids are at low temperatures during anaerobic treatment, a phenomenon that has been reported in numerous studies for slaughterhouse wastewater [2,3,4]. Even after successful primary pre-treatment, further lipid removal might be required in a process.…”

Inhibition of anaerobic digestion processes: Applications of molecular tools

“…For example, a study that used slaughterhouse waste feed reported that dilution of inhibitory compounds with co-digestion led to improved methane yield compared to mono-digestion reactors (Astals et al, 2014). Other methods for inhibition mitigation include thermal pre-treatment (Ennouri et al, 2016), alkaline pre-treatment (Koyama et al, 2017), and enzyme addition (Meng et al, 2017). A study that evaluated the addition of three lipases to hydrolyze food waste rich in crude lipid revealed that using two of the lipases increased methane production by 81-158% in animal fat, 27-54% in vegetable oil, and 37-41% in floatable grease waste digestions (Meng et al, 2017).…”

Improving the stability and efficiency of anaerobic digestion of food waste using additives: A critical review

“…A previous study showed that the lag phase of wastes rich in lipids was about 20.2-48.7 d. This was much longer than that of other wastes (about 14.9-19.9 d) (Lou et al, 2012). A study by Meng et al (2015) showed that FW in China (rich in lipids such as floatable grease from animal fat and vegetable oil), could greatly benefit from lipase additive during hydrolysis, with methane production increase of 37.0-40.7% in digestion time of 10-40 d (Meng et al (2017).…”