Sludge from paper mill wastewater treatment plant is the residual composed of fibres fibre particles and miscellaneous debris. Sludge with high fibre contents were collected from BP paper mill industry. They were retreated by 2 days drying and mixing dried sludge with tapioca starch as ratios were: 100:0 95:5 90:10 85:15 and 80:20(sludge: tapioca starch). To make the green energy block by using screw-press machine compressed sludge that mixed with various ratios of tapioca starch. A size of green energy block was 6 inches diameter 2 inches high and 150 g. weight. Energy values were tested by using Bomb-calorimeter measurement instrument. The results of testing found: the best ratio of green energy compressed for high heating value was 95:5(sludge : tapioca starch by weight) and the maximum heating value was about 19638 J/g. This green energy block made from waste of paper mill wastewater treatment plant is a way of recycle waste to be energy and reducing waste from industry.

This study surveyed seventeen wastewater treatment plants in concentrated latex rubber and seafood industries in southern Thailand. The researchers concerned mainly in the bulking sludge problems caused by filamentous bacteria. Wastewaters from those factories contained high organic contents high BOD5 and TKN concentrations. All of the existing activated sludge process were equipped with other pre- and post-treatments. Sixteen of them were concerned with only carbon and suspended removal. They were operated with high hydraulic retention time (HRT) and low food per microorganism ratio (F/M ratio) which are the main causes of bulking sludge problem. Most operators faced up with this problem but could not realize the reasons and solutions. This study observed their settle ability and presented filamentous bacteria in each plant. It can be evidently seen that some filamentous bacteria such as type 0041 and Nostocoida limicola II appeared at seafood treatment plants only and type 1863 found in rubber treatment plants only. This can be affirmed to the nature of influent composition of wastewater.

The purposes of this research were to investigate anaerobic digestion of concentrated food waste in biogas production system at mesophilic temperature (37 C). The effect of grinding and pH controlled at 6.20 and 7.00 on methane production were also studied. It was found that the ability of mix bacteria which had initial concentration of 2100 mg/l for digesting concentrated food waste with grinding was higher than that without grinding because of the increase in surface area (about 1.37 time). In this system the optimum condition for bacteria growth was found at pH 7.00. Under optimal condition the digestion efficiency in term of chemical oxygen demand (COD) removal was 18.81% higher corresponding to an increase in methane production rate (19.10%) than other conditions