l. Introduction
Developments in intensive agricultural techniques have been promoted throughout
Thailand. They give benefits in terms of earnings, but at the same time can cause many environmental problems. Most agricultural effluents, such as those from swine farming for example, are discharged directly to the waterways and considered to be one of the most serious water pollution sources of major rivers in Thai land[5 ,13] .
The use of only conventional methods in treating swine wastewater, such as anaerobic ponds and anaerobic digesters, cannot succeec in meeting the effluent standard [3]. Using Chlorella sp. as a biological treatment process, for further treatment of this wastewater. however, results in high efficiency [2,8]. It not only removes certain amounts of organic substances and nutrients, but also produces
useful by-products of algal cell, which have various uses. However, a proper biomass is removal process is needed in order to prevent re-pollution of water resources.