Odour
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Odour Assessment and Control

A. Summary of activities

The odour research laboratory in The Hong Kong Polytechnic University was established in 1995 and an odour specialist team has been actively conducting odour related research and consultancy and providing some short courses for local engineers. Examples are:

	Standardisation of odour measurement procedure by dynamic olfactometry
	Identification and classification of odour emission sources using electronic nose technique
	Development of odour sampling techniques for point, area and volume sources and field inspection for routine odour monitoring by qualified panellist
	Application of odour dispersion modelling and odour impact assessment for existing operations and new developments.
	Development of odour treatment processes such as water scrubbers, bioreactors and adsorption systems
	Education and training for local engineers

B. Major facilities

	Olfactometer
	Electronic nose
	Odour sampling equipment with dilution function
	Lab-scale and pilot-scale bioreactors for odour treatment

Odour measurement

A wind tunnel for odour sampling

C. Recent output of research and consultancy

Development of a novel fibrous bed bioreactor system for odour treatment

The project was supported by the Research Grants Council of Hong Kong. The objectives are to investigate the odour pollution problems from local wastewater treatment plants and to develop a cost-effective odour control system. A newly innovated fibrous bed bioreactor with twin columns was specially designed and constructed in our laboratory. In this study, hydrogen sulphide and butyric acid were used as odorous components and successfully removed from synthetic foul gases with reduction rates of 97.8% for H₂S and 99.9% for butyric acid respectively. It is proved that this bioreactor was a compact odorous gas treatment system with an application potential for treating foul air with high odour strength and low flow rate such as the offensive gases from sludge treatment processes in wastewater treatment plants.

Adsorption of VOCs by natural zeolite

The natural zeolite from Australia was employed in the experiment to remove odour from three (wet and dry) odorous gases containing the volatile fatty acids (VFAs) from C₂ to C₇generated in laboratory. Experiments demonstrated that the preconditioning of the natural zeolite was of benefit to the increase of the adsorption capacity and the natural zeolite had selectively and preferentially adsorbed the VFAs with big molecular weights. Regenerating the exhausted zeolite for 1hr at 550°C could restore 92% of the adsorption capacity.

An experimental study on odour emisssion determination during dredging operation in Shing Mun River

An odour assessment service at Shing Mun River was required by Aspinwall Clouston Limited to determine the odour emission rate during its dredging operation, in which two on-site experiments were conducted for the quantification of odour emission rates from disturbed sediment to simulate odour impact during dredging operation.

On-site odour assessment at North Lantau Refuse Transfer Station

The odour emission from the newly established North Lantau Refuse Transfer Station was assessed for Ecoserve Limited, which included the determination of the odour removal efficiency of the existing scrubbers and odour assessment at the nearest air sensitive receivers (ASRs) by applying the ISCST dispersion model. A contour map of odour distribution as shown indicates the odour pollution impact in the surrounding area from the emission source.

Short course provided

Odour sampling, measurement and assessment- A short course on 10 – 12 September 1998, Hong Kong

D. Selected recent output

	Chua H., Li X.Z., Tam C.Y., Huang Y.L. and Yang S.T., Deodorization of contaminated air by immobilized microbes, Toxicol. Environ. Chem., 72,171-181, 2000.
	Chua H., Li X.Z., Yu P.H.F., Tam C.Y., Huang Y.L. and Yang S. T., Performance of fibrous bed bioreactor for treating odorous gas, Appl. Biochem. Biotechnol., 77-79, 561-569, 1999.
	Chua H., Li X.Z., Yu P.H.F., Tam C.Y., Huang Y.L. and Yang S.T., Design and performance of a fibrous bed bioreactor for odor treatment, Appl. Biochem. Biotechnol., 84-86, 469-478, 2000.
	Li X.Z. Development of odour measurement technique and improvement of odour control policies (in Chinese), Environmental Science, 20(2), 107-109, 1999.

E. Contact person

Dr. X. Z. Li, Associate Professor

Tel: (852) 2766 6016; Fax: (852) 2334 6389; E-mail: cexzli@polyu.edu.hk

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