Practices in the Management of Domestic Fats, Oil and Grease

Ho Yuek Ming1,a and Nur Azura Berahim2,b 1Faculty of Environmental Studies, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor,

Malaysia

2Faculty of Environmental Studies, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia

asabrina@env.upm.edu.my, bazuraberahim@gmail.com

Keywords: Fats, oil and grease(FOG), domestic waste disposal, waste management

Abstract.

Obstruction by fats, oil and grease (FOG) clogs in sewer pipelines results in high building

maintenance costs. FOG in wastewater poses threats to properties and causes pollution of

waterways and groundwater. A survey was carried out among residential households in the

suburban township of Bandar Baru Bangi, Malaysia, to identify domestic practices in the handling

and management of kitchen wastes. Improper practices in the disposal of kitchen wastes containing

FOG is found to be the major cause of FOG accumulation in sewer pipes and drains. Preventive

practices in the management of FOG in domestic kitchen waste should be the first line of solutions

in mitigating FOG.

Introduction

Wastewater from residential areas normally contains both organic and inorganic wastes such as

chemical cleaners and detergents. Organic wastes usually come from kitchen sinks, dishwashers and

floor drains. A large proportion of kitchen waste consists of food scraps that contain fats, oil and

grease (FOG). Very often, such kitchen wastes are washed down sewer pipes and cause sewer pipe

blockage, which leads to sewer spills and overflows. This may result in damages to properties and

the pollution of local waterways and groundwater [1].

Fats, oil and grease is a by-product of cooking. It is found in food such as meat, fats, used

oil, butter, margarine, food scraps, sauces, and dairy products. It is categorized as a solid or viscous

substance. If not properly disposed, it will cause obstruction in the sewer line system. When

flushed down the kitchen sink or drain, FOG sticks to the insides of sewer pipes. Over time, FOG

can build up and block entire pipes. Very often it is almost impossible to remove such clogs and the

sewer pipes may need to be replaced. This results in high maintenance costs to buildings, especially

high rises.

Management of kitchen waste and FOG is a major problem nowadays in cities and towns

due to rapid increase in the number of restaurants, hotels, cafeterias and also residences. Problems

due to FOG occurrs not only in Malaysia. It is a common problem worldwide. In 2000, the Hong

Kong Drainage Services Department (DSD) claimed that more than 60% of sewer blockages were

due to excessive build-ups of grease [2]. Kitchen waste consitute 69.3%, the largest component of

household waste in Beijing, China [3]. In Malaysia, it is found that the major contribution to sewer

blockages is from FOG build up in sewer pipes [4]. FOG enters the sewage system mostly due to

households pouring used oil and kitchen wastes into the kitchen sink or during cleaning operations

at food service facilities.

Most residential households lack awareness and knowledge of where the kitchen waste goes

to after being disposed. Thus, their attitude and current practice of disposing kitchen wastes directly

into the sink gave rise to the FOG problem in the municipal sewer system, and the environment as a

whole. Preventive practices in the management of domestic FOG discharge into the wastewater

sewer system could reduce this problem.

Advanced Materials Research Vols. 781-784 (2013) pp 2036-2039Online available since 2013/Sep/04 at www.scientific.net© (2013) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMR.781-784.2036

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This study assessed the practices of households in the management of kitchen waste

containing FOG. Findings from this study could help the relevant authorities determine the factors

that contributed to sewer blockages, and find preventive solutions in the management of domestic

FOG. Awareness programs could then be implemented to mitigate this problem.

Methodology

The study was conducted in the suburb township of Bandar Baru Bangi (2o57’55” N and 101

o45’9”

E), Malaysia. This township with sprawling residential areas has a population of 123,500 [5].

Structured questionnaires were administered to 200 residents in selected residential areas.

Participants were asked to repond to 10 statements referring to practices on kitchen wastes and FOG

disposal based on a Likert scale of 1- 5. Secondary data were retrieved from the official website of

Indah Water Konsortium (IWK), the national agency that manages the integrated sewage treatment

plants in Malaysia.

Results and Discussion

Figures 1 to 3 show the number of public complaints on sewer blockages and overflowing manholes

received by Indah Water Konsortium between November 2012 and April 2013 [6].

Fig. 1 Complaints Received on Blockage within private premises

Fig. 2 Complaints Received on Blockage at Public Sewerage Pipelines

Advanced Materials Research Vols. 781-784 2037

Fig. 3 Complaints Received on Overflowing Manholes

(Figures 1 to 3 are extracted from the Indah Water Konsortium (1WK) official website

www.iwk.com.my)

It could be clearly seen that the trend of the three graphs matches. The blockages in private

premises coincides with the number of blockages found in public sewerage pipelines and the

number of overflowing manholes. When FOG particles are washed through kitchen sinks and floor

drains, they will build up and eventually block entire pipelines, causing blockage to public pipelines

and overflowing manholes [1,7]. This often leads to property damage, health hazards and a foul

environment.

The survey on household practices on kitchen waste disposal reveal that proper treatment of

FOG is still lacking. Only 50% of the households sometimes separate their kitchen waste from other

household wastes. Only 50% of the respondents say they sometimes use a paper towel to clean

their plates before washing. Very few sell their used cooking oil to be recycled. None of the

households surveyed installed a grease trap in their kitchens. In Malaysia, grease traps are only

installed in commercial buildings and full service restaurants [8].

On the positive side, a majority of the households surveyed do not throw used cooking oil

and soup into their kitchen sink. Most of them said they do not throw kitchen wastes into the sink

either.

Conclusion

Management of domestic fats, oil and grease in Malaysian homes is still wanting. Best

management practice is an effective tool in controlling the FOG. Awareness campaigns on how to

prevent FOG from getting into the sewer system will help to lower maintenance costs incurred.

Local authorities could enforce regulations not only on large commercial food premises but to

residential households as well.

References

[1] Matsui, T., Miura, A., Iiyama, T., Shinzato, N., Matsuda, H,. and Furuhashi, K., 2005.

Effect of fatty oil dispersion on oil-containing wastewater treatment. Journal of

Hazardous Materials. 118 (1-3): 255-258.

[2] Chan, H., (2010). Removal and recycling of pollutants from Hong Kong restaurant

wastewaters. Bioresource Technology. 101 (17): 6859-6867.

[3] Qu, X., Li, Z., Xie, X., Sui, Y., Yang, L. & Chen, Y. 2009. Survey of composition and

generation rate of household wastes in Beijing, China. Waste Management. 29: 2618-2624.

2038 Advances in Chemical Engineering III

[4] IWK. List of STPs Public Complaint. January-December 2011.

[5] Department of Statistics Malaysia. 2010.

[6] Indah Water Konsortium http://www.iwk.com.my

[7] M. Aqeel A., M. Jamil M., Ismail Y., 2010. Water quality characterization of Varsity Lake,

University of Malaya, Kuala Lumpur, Malaysia. E-Journal of Chemistry. 7 (S1): S245-

S254.

[8] Wong, N.H., Law, P.L. & Lai, S.H. 2007. Field tests on a grease trap effluent filter.

Int.J.Environ.Sci.Tech. 4(3): 345-350.

Advanced Materials Research Vols. 781-784 2039

Advances in Chemical Engineering III 10.4028/www.scientific.net/AMR.781-784 Practices in the Management of Domestic Fats, Oil and Grease 10.4028/www.scientific.net/AMR.781-784.2036