Fat, Oil And Grease Research Articles

Mechanisms of Fat, Oil and Grease (FOG) deposit formation in sewer lines

FOG deposits in sewer systems have recently been shown to be metallic salts of fatty acids. However, the fate and transport of FOG deposit reactant constituents and the complex interactions during the FOG deposit formation process are still largely unknown. In this study, batch tests were performed to elucidate the mechanisms of FOG deposit formation that lead to sanitary sewer overflows (SSOs). We report the first formation of FOG deposits on a concrete surface under laboratory conditions that mimic the formation of deposits in sewer systems. Results showed that calcium, the dominant metal in FOG deposits, can be released from concrete surfaces under low pH conditions and contribute to the formation process. Small amounts of additional oil to grease interceptor effluent substantially facilitated the air/water or pipe surface/water interfacial reaction between free fatty acids and calcium to produce surface FOG deposits. Tests of different fatty acids revealed that more viscous FOG deposit solids were formed on concrete surfaces, and concrete corrosion was accelerated, in the presence of unsaturated FFAs versus saturated FFAs. Based on all the data, a comprehensive model was proposed for the mechanisms of FOG deposit formation in sewer systems.

Biodiesel from grease interceptor to gas tank

AbstractThe need for sustainable biofuels has initiated a global search for innovative technologies that can sustainably convert nonfood bioresources to liquid transportation fuels. While 2nd generation cellulosic ethanol has begun to address this challenge, other resources including yellow and brown grease are rapidly evolving commercial opportunities that are addressing regional biodiesel needs. This review examines the technical and environmental factors driving the collection of trap FOG (Fats, Oils, and Greases), its chemical composition and technologies currently available and future developments that facilitate the conversion of FOG into biodiesel.

Free fatty acids degradation in grease trap purification using ozone bubbling and sonication

The oil and fat were treated at first by only ozone bubbling and it was confirmed that the collection efficiency of them became 98.4% when the aeration was used. It showed that the aeration method in a grease trap cleared the standard value of 90% and there was no worry on the oil and fat outflow from a grease trap. The characteristics of sonication process were studied for free fatty acids degradation. The free saturated fatty acids are the most hard-degradable compounds of the fats, oils and greases (FOGs) in the grease trap. The influence of various parameters such as immersion level of an ultrasound probe in the liquid and bubbling of various gases (Ar, O2, air, O3) on the sonochemical and energy efficiency of the sonication process was investigated. The most effective degradation treatment method for saturated free fatty acids was the combination of sonication and low flow rate argon bubbling.

Anaerobic co-digestion of FOG and sewage sludge: Study of the process by Fourier transform infrared spectroscopy

The digestion of residues with high lipid content was investigated. The experimental work focussed on the assessment of co-digestion of sewage sludge and fat, oil and grease (FOG) residues separated from the grease trap of the pre-treatment system of a wastewater treatment plant. A 0.2% volumetric ratio was set, based on the volumetric production of these streams in the plant. The digestion was carried out under semi-continuous operation at mesophilic temperatures. The operation of reactors at a hydraulic retention time (HRT) of 30 days resulted in no observable modifications of the specific methane production when compared to results obtained from sludge digestion and co-digestion systems. However, a decrease in HRT resulted in the detriment of the co-digesting reactor, which was attributed to an inhibitory process associated with the adsorption of FOG onto active sludge.

Production of Polyhydroxyalkanoates from Fatty Wastes

The production of polyesters from triglyceride containing substrates was investigated. A first filter step based on lipase activity was followed and those bacteria potentially able to degrade oils or animal fats were further tested for their polymer accumulation properties, selected and kept for further studies. In a second step, bacteria were directly grown on animal fats and/or vegetable oils, and polyhydroxyalkanoates (PHAs) accumulation was verified under appropriate incubation conditions. Each substrate, whether of animal or vegetable derivation, supported the growth of a number of the newly isolated strains and among those, some strains were also found to produce reasonably high amounts of PHA. The repeat-unit composition of the polyesters was determined by gas chromatography (GC) analysis of the s-hydroxyalkanoate methyl esters from the hydrolyzed polymer and some class of co-polymers were also detected. These properties, coupled with the ability of some of the selected isolates to grow and produce lipases on a minimal medium, could be considered as promising in view of possible industrial applications. The overall results indicate that PHAs could be produced from waste containing considerable amounts of fat, oil and grease (FOG), that generally need to be treated for their disposal.

Network based controller systems for pre-conditioning of waste water in sewer systems

Sewer network odour emissions have become a focus due to environmental regulations and, in the case Hydrogen Sulphide (H2S) induced corrosion, due to safety and sustainability. For these reasons the establishment of emission treatment is recommended. Sewer emission treatment focuses on local solutions rather than sewer-wide network treatment. The dosing of chemicals for this purpose is usually done section-wise. Obviously there is optimization potential when sewers are understood and treated as networks. Preventive treatment can be optimized by information from downstream and curative treatment by information from upstream. Such concepts demand communication technology and monitoring of several parameters at various locations in the sewer network. In the presented case study a digital communications network is used to control H2S emissions and fat, oil and grease (FOG) disposal in a sewer network. Moreover it was shown that technical solutions are available to use sewers as controlled reactors rather than just let them be a source of problems. An overview of today's standard dosing systems and strategies for odour and corrosion control is also given.

Side effects of cultured bacteria addition in wastewater collection system on plant operations – a case study

Cultured bacteria addition is one of the technologies used for odor control and FOG (fat, oil, and grease) removal in wastewater collection systems. This study investigated the efficiency of bacterial addition on wastewater odor control by conducting a set of full scale trials in a 60,000 cubic meter per day system for a period of two years. The objectives of this study were: (i) to identify factors that could impact wastewater treatment plant (WWTP) operations due to the effect of bacterial addition in the collection system, (ii) to estimate/understand the level of those impacts, and (iii) to present some interesting findings from the completed case study. The plant operation data before and during the bacterial addition were reviewed. The application of the cultured bacteria presented in the study was found to have significant impacts on the operation of the WWTP in terms of influent biological oxygen demand (BOD) and total suspended solids (TSS) loading, primary settling, sludge production, energy use, dissolved sulfides concentration, and methane production.

Removing Fats, Oils and Greases from Grease Trap by Hybrid AOPs (Ozonation and Sonication)

The purpose of this study was to investigate the electrical energy for the environmental applications using AOPs (advanced oxidation processes) combined with ozonation and sonication to remove the FOG (fats, oils and greases) from wastewater of the sewage system. This study focused on FOG removal from a grease trap using the hybrid AOPs. Fatty acids (linoleic, oleic, stearic and palmitic acids) were used as representative standards of FOG. The studies were conducted experimentally in a glass reactor under various operational conditions. The oxidation efficiency using the combination of the ozonation and sonication was determined by the KI dosimetry method and the calorimetry method. Fatty acids concentration were measured by GC/MS. The local reaction field of the high temperature and high pressure, so-called hot spot, was generated by the quasi-adiabatic collapse of bubbles produced in the water under sonication, which is called cavitation phenomenon. Mixing the ozone bubbles into the water under acoustic cavitation, the formation of OH radicals increased. The mechanical effect of acoustic cavitation such as microstreaming and shock waves have an influence on the probability of reactions of ozone and radicals with fatty acids.

Effects of Pre-fermentation and Influent Temperature on the Removal Efficiency of COD, NH4+-N and PO43–-P in Slaughterhouse Wastewater by Using SBR

A sequencing batch reactor (SBR) was used to remove COD, NH4+-N and PO43--P in slaughterhouse wastewater at different temperatures. A complete operation cycle was 7h, which consisted of fill, aeration(5h), settling(1h), stationary(1h) and drawing. Conventional treatment technologies were unsuccessful in treating slaughterhouse wastewater because it contained substantial amounts of fat, oil and grease (FOG). The SBR process showed great nutrient removal performances after 7 days prefermentation. The removals of COD, NH4+-N and PO43--P were 99%, 85% and 99%, respectively. The increase in effluent volatile fatty acid (VFA) and phosphate concentrations after prefermentation may explain the high levels of biological carbon, nitrogen and phosphorus removal observed. The results also showed that 30 C was found to be the most suitable temperature as the removal efficiency of COD, NH4+-N and PO43--P was 96%, 92% and 91%, respectively.

Artificial Recharge via Boreholes Using Treated Wastewater: Possibilities and Prospects

Interest in artificial recharge of groundwater using pretreated wastewater continues to increase, especially in semi-arid countries. After the artificial recharge and natural treatment, the water could be extracted through boreholes pumping for direct irrigation. The selection of suitable locations for artificial recharge should be based on hydrogeological conditions, economic evaluation and environmental considerations. Clogging of boreholes that are used for artificial recharge is a serious problem and requires proper planning to reduce it. This paper deals with the investigation of the possibilities and prospects of aquifer recharge via boreholes using treated wastewater. Firstly, the aquifer recharge techniques, the proposed criteria of waste and the clogging effect are presented. Secondly, the possibility of application of artificial recharge in the South-Eastern Mesaoria aquifer of Cyprus is examined. Based on hydrogeological results, artificial recharge using tertiary treated wastewater via boreholes is one of the options available for increasing the groundwater reserves of this aquifer. The recycled water will infiltrate through gravel pack, providing favorable conditions for ventilation and laminar flow due to small water flow velocity. The treatment works include the removal of the fat, oil and grease (FOG) and cyanides (CN−) content in order to meet the upper acceptable limits.

Fat, oil and grease - Sewer contamination prevention strategies and double-dosage concept for fat traps and pressure mains

Disposal of fat, oil and grease (FOG) in sewer systems cause blockages, fatal errors of pumping stations, increased maintenance, odours, hydrogen sulphide (H2S) emissions and corrosion. Hence, solutions to prevent FOG disposals are desirable. Challenges are prevention of FOG contamination of sewer systems and removal of FOG disposals. A survey and lab as well as full scale tests were performed. In the first place fat traps and grease inceptors should be installed to prevent FOG contamination what is documented as being very effective. A case study shows that the operation of fat traps may indeed produce further problems, especially H2S emissions, what demands an additional treatment. Removal of FOG disposals can be handled by applying enzymes to the affected sewer network. It was found that enzymes are preferable towards surfactants to remove FOG disposals. It appears to be a solution to have one dosing site that is equipped with separately controlled dosing pumps for conditioners for H2S removal as well as FOG removal.

Semi-continuous anaerobic co-digestion of thickened waste activated sludge and fat, oil and grease

Co-digestion of thickened waste activated sludge (TWAS) and fat, oil and grease (FOG) was conducted semi-continuously under mesophilic conditions. The results showed that daily methane yield at the steady state was 598 L/kg VS added when TWAS and FOG (64% of total VS) were co-digested, which was 137% higher than that obtained from digestion of TWAS alone. The biogas composition was stabilized at a CH 4 and CO 2 content of 66.8% and 29.5%, respectively. Micronutrients added to co-digestion did not improve the biogas production and digestion stabilization. With a higher addition of FOG (74% of total VS), the digester initially failed but was slowly self-recovered; however, the methane yield was only about 50% of a healthy reactor with the same organic loading rate.

Whole cell‐catalyzed transesterification of waste vegetable oil

AbstractEnzymatic transesterification of waste cooking oil, comprising fats, oil and grease (FOG), to produce fatty acid methyl esters (FAME) i.e. biodiesel, was investigated using a novel strain of the fungus Aspergillus niger, immobilized as a whole‐cell biocatalyst. Response surface methodology (RSM), with a five‐level‐three‐factor central composite rotatable design, was used to optimize the reaction and analyze the relationship of reaction variables and their coinfluent on the response i.e. FAME yield. Independent variables that affect the transesterification reaction include temperature, feedstock water content and enzyme amount. Using RSM, a second‐order polynomial equation was derived for FAME yield using multiple regression analysis. The second‐order polynomial regression model was highly significant (P<0.001) in predicting the actual relationship between the response and the variables, where a linear relationship was apparent between observed and predicted values (R2=0.9651). In addition, the predicted determination coefficient q2 i.e. 0.7723, also proved that the model has a high predictive ability. The validation experiments, under optimized conditions, showed that the predicted value of maximum FAME yield (i.e. 91.3%) was in close agreement with the experimental value (i.e. 91.8%).

The impact of bioaugmentation on fats, oils and greases (FOGs) degradation and activated sludge biodiversity

The impact of bioaugmentation on fats, oils and greases (FOGs) degradation and activated sludge biodiversity

Recovery and pre-treatment of fats, oil and grease from grease interceptors for biodiesel production

Fats, oil and grease (FOG) can be recovered efficiently from grease interceptors for biodiesel production. FOG is susceptible to hydrolysis because of its inherent high moisture content and the presence of lipases associated with food residuals in the grease interceptors. This study reveals that the FFA content of FOG derived from grease interceptors did not exceed 8% (w/w) due to constant influx of fresh FOG from wastewater. However, if the FOG is allowed to hydrolyze without dilution, the FFA content can reach 15% (w/w) in more than 20 days. Experiments were conducted to optimize reaction parameters for the esterification of FOG prior to the conventional alkali-catalyzed biodiesel production process. Sulphuric acid (H 2SO 4) was a more efficient catalyst than Fe 2(SO 4) 3 in reducing the acid value to ⩽1 mg KOH/g under identical reaction conditions. At reaction temperatures of ⩽50 °C, only H 2SO 4 was capable of reaching the recommended acid value within 24 h. The optimum methanol to FFA ratio for an H 2SO 4-catalyzed reaction was 20:1, whereas for Fe 2(SO 4) 3 it was above 26:1. Esterification occurred under static, non-mixed conditions, although conversion rates were low. The rate of conversion increased with mixing speed, with a 200 rpm orbital shaking speed as optimum.

Feeding FOG to Thermal Oxidation Units It's All in the Presentation

Feeding FOG to Thermal Oxidation Units It's All in the PresentationThe Hampton Roads Sanitation District (HRSD) has developed a simple and effective system for recovering the energy value of the fat, oil and grease (FOG) waste receipts at its Williamsburg Treatment Plant (WTP). The solids and FOG production at this treatment plant are thermally oxidized by multiple hearth incineration, with the energy recovered in the form of reduced natural gas consumption. The...Author(s)Timothy G. SheaDavid CooleyPeter BurrowesSourceProceedings of the Water Environment FederationSubjectSession 17: Incineration and DryingDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2010ISSN1938-6478SICI1938-6478(20100101)2010:4L.1162;1-DOI10.2175/193864710802767362Volume / Issue2010 / 4Content sourceResiduals and Biosolids ConferenceFirst / last page(s)1162 - 117Copyright2010Word count174Subject keywordsFat-Oil-Grease (FOG)primary scumscum concentrationDCS (decanted concentrated scum)blending of DCS and dewatered sludge cakemultiple hearth incinerationcost-effectiveness

Maximizing Energy Recovery from Sludge - Singapore's Approach

Recovery of energy from sludge is an important component of PUB's drive towards zero-energy input for used water treatment in its Water Reclamation Plants (WRPs). Driven by this vision, PUB has taken steps to boost biogas production from the conventional mesophilic digestion process via 1) ultrasonic sludge disintegration and 2) co-digestion of greasy waste and used water sludge. From trials in Ulu Pandan WRP, ultrasonic sludge disintegration can boost biogas production by 35%. The paper will describe the pilot-scale trial in detail, including the operational problems that were encountered. In addition, this paper covers the operation of a centralised facility at Jurong WRP - the first of its kind in Asia that has been built to receive fats, oils and greases (FOG) from grease interceptors in Singapore. By blending FOG with thickened sludge (5% TS) before anaerobic digestion, the production of electricity from biogas at Jurong WRP has increased to almost 50% of the total energy consumption necessary for its treatment processes. These exciting initiatives form the cornerstone of PUB's current efforts to reduce the carbon footprint for used water treatment.

The Ultimate Anaerobic Biodegradability of Municipal Sludge and FOG

The Ultimate Anaerobic Biodegradability of Municipal Sludge and FOGThe anaerobic biodegradability of three types of municipal sludge (primary, secondary, and dewatered secondary), as well as two types of partially dewatered (polymer dewatered and lime dewatered) fat, oil and grease (FOG) was assessed at 35°C using a previously digested anaerobic sludge as seed. Samples of these five components, as well as various combinations of the individual components were...Author(s)J.C. KabourisU. TezelS.G. PavlostathisM. EngelmannJ. DulaneyR.A. GilletteA.C. ToddSourceProceedings of the Water Environment FederationSubjectSession 85: Getting More Out of Your Digester and ProcessDocument typeConference PaperPublisherWater Environment FederationPrint publication date Oct, 2007ISSN1938-6478SICI1938-6478(20071001)2007:11L.6776;1-DOI10.2175/193864707787223763Volume / Issue2007 / 11Content sourceWEFTECFirst / last page(s)6776 - 6792Copyright2007Word count298Subject keywordsANAEROBIC DIGESTIONFOGMETHANE PRODUCTIONMUNICIPAL SLUDGECO-DIGESTION

Degradation and modification of fats, oils and grease by commercial microbial supplements

Fats, oils and greases (FOGs) in wastewater create problems including the production of foul odours, the blockage of sewer lines and may interfere with the proper operation of sewage treatment works. Removal of FOG from wastewater is thus critically important to ensure that wastewater is disposed of efficiently and economically. In this study, the ability of commercial microbial supplements to degrade fat/oil under laboratory conditions was investigated. One of the multi-species supplements examined was capable of significantly enhancing the degradation of several fats and oils by 37–62%, in contrast to all of the single-species supplements which had no significant effect. The multi-species supplement showed no preferential cleavage or degradation of fatty acids in a range of FOGs, whilst wastewater-associated bacteria preferentially degraded octadecatrienoic acid (18:3ω3) and octadecadienoic acid (18:2ω6). A semi-solid, sticky material, likely to cause blockages in pipework and sewer lines formed when the oil was incubated in the presence of wastewater bacteria. The sticky material was enriched in saturated and mono-unsaturated fatty acids and depleted in polyunsaturated fatty acids relative to the original oil, most likely reflecting preferential fatty acid usage by the bacteria. The production of this semi-solid material by the wastewater bacteria was significantly reduced by the presence of the multi-species product, indicating that commercial supplements have the potential to minimize FOG accumulation and blockages in grease traps and sewer lines as well as enhancing FOG degradation.

Evaluation of activated sludge treatment and settleability in remediation of edible oil effluent

Wastewater discharged from the edible oil industry contains a very concentrated amalgamation of organic and inorganic materials making it a problematic effluent to treat. The aim of this study was to evaluate the activated sludge treatment of edible oil effluent from a sunflower oil processing company in KwaZulu-Natal. A 28 ℓ laboratory-scale modified Ludzack-Ettinger (MLE) activated sludge process was used to treat refinery effluent from the industry. Pre-flocculation of the effluent was necessary to remove the bulk of the fats, oils and greases (FOG) prior to treatment. Routine analyses of chemical oxygen demand (COD), total nitrogen (N), total phosphorus (TP), total suspended solids (TSS), dilute sludge volume index (DSVI) and FOG were conducted in conjunction with microscopic analyses of floc structure, filamentous bacteria and protozoa. An average COD removal of 81% was obtained for the flocculated effluent, at a 15 d sludge age and 24 h hydraulic retention time. However, significantly high TSS values were observed in the treated effluent as a result of sludge-oil aggregation, pin-point floc formation and high numbers of freeswimming bacteria. Microscopic analysis confirmed an absence of filamentous bacteria resulting in poor floc formation, subject to shearing. Periods of soybean oil effluent addition, however, resulted in sludge bulking with DSVI measurements as high as 770 mℓ /g. Fluctuating protozoan populations were also correlated to fluctuating TSS values and were found to be negatively impacted by uncontrolled pre-flocculation. Water SA Vol.29(3) 2003: 245-250