dc.description.abstract |
Rapid Degradation of FOG Discharged from Food Industry Wastewater by Lipolytic
Fungi as a Bioaugmentation Application
Fats, oils, and grease (FOG) congregate in grease trap devices as a result of culinary activities in the
foodservice industry. FOG is considered to be slowly biodegradable particulate (sbpCOD) organic
matter and may require enzymatic or hydrolytic conversion to form readily biodegradable soluble
organic matter (rbsCOD). The existing treatment methods are claimed on water-based hydrolysis of
FOG to form long chain fatty acids. The long chain fatty acids discharged into wastewater treatment
systems create functional difficulties, especially the inhibitory effect caused by the accumulation of
such fatty acids. In order to overcome the issues associated with water-based treatment systems, FOG
was extracted from the waste and solid-state degradation was performed by lipolytic fungi in a traytype
reactor as a novel approach of bioaugmentation. In the reactor, each 10 mg/g dry weight of FOG
(substrate) was mixed with 1% w/v of coir fiber for proper aeration. Then the reactor was inoculated
with 1 mL of spore suspension (1 × 107 spores/mL) of lipolytic fungi. The isolated lipolytic fungi
were Aspergillus niger, Geotrichum candidum, Aspergillus fumigates, Fusarium proliferatum and
Penicillium citrinum. The optimum conditions to degrade grease trap waste by solid-state degradation:
initial moisture content of FOG should be 25 – 35% of weight; temperature 30°C; pH should be
between 6–7; the reactor moisture condition for continuation of degradation process should be
maintained around 65%. The higher degradation efficiencies (>80%) were recorded by these fungi
isolates. As a practical application of the developed methodology, solid-state degradation was
performed with raw grease trap waste (without extraction of FOG) in room temperature without
adjusting the pH. The recorded pH for grease trap waste varied between 4.5–6.5 and most abundant
fatty acids present in grease trap waste were palmitic acid 49.5% (w/w) and oleic acid 33% (w/w).
Within 72 h of post-incubation, degradation efficiency of about 50% was recorded by fungal isolates.
The degraded residue can be used as an inoculum for the degradation of the second set of grease trap
waste. Therefore, once the degradation cycle is started, continuous inoculation for the rest of the
degradation process would not be needed. The feasibility of using the developed protocol for FOG
degradation was tested with a laboratory-scale tray type reactor, and it was operated successfully. |
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