Biogas production and wastewater treatment with UASB for food industry  

This project involves biogas production and wastewater treatment in a food processing industry in Thailand. Papop has undertaken the main contractor role. The whole project was completed in 1 year. Thai Environmental & Energy Development Co., Ltd. was the designer and act as the consultant.   

The key processes for the project consisted of Dissolved Air Flotation (DAF), Upflow Anaerobic Sludge Blanket (UASB) and Screw Press. The most challenging task for this project was the limitation of the construction area which has a width and length of 11 m and 37 m, respectively. The area was so small that it was only possible to stake 2 UASB tanks on top of each other. All units were built into a single building with total height of 17 m.  

The whole system was designed to treat 4,500 cu.m. of wastewater per day. The process starts from the equalization tank, then the wastewater goes to Dissolved Air Flotation (DAF) for oil and grease removal. There are 2 DAF units on the top most part of the building. Each unit has a diameter of 8 m and can accept 4,800 cu.m. per day of wastewater. This is almost one of the largest DAF units in Thailand.  

The special features of this DAF process are as follows: 

  • Able to generate micro bubble with the common rail injection method with high frequency. It is possible to achieve very high oxygen dissolve rate of 27% within 3 seconds. 
  • The diameter of the micro bubble is only around 3 to 7 Micron. While conventional DAF Process has a size of bubble at around 500 to 600 Micron. Hence, this process can achieve smaller bubble size up to 200 times than the conventional process. 
  • With this special machine and such a small micro bubble, oil and grease removal efficiency can be achieved up to 99%. 
  • Smaller footprint can be realized with such a high efficiency and shallow tank. 
  • The unit generates lesser noise than the conventional ones. 
  • Less moving part means lower power consumption and less maintenance. 

The sludge that is removed from DAF unit is transferred to the screw press. The effluent from DAF is delivered the 4 UASB tanks. There are 2 tanks (UASB 3 and 4) on the top and 2 tanks (UASB 1 and 2) at the bottom of the whole building.     

Papop has over 30 years’ experience in designing of the UASB process in Thailand. There are 40+ installations in Thailand and Southeast Asia. The process can be applied to food processing industry and other agriculture industries such as tapioca as well as ethanol industries. 

The space between UASB 1, 2 and 3, 4 is designed to house a control room, chemical feeding units, pumping units and all other equipment. The control room is designed to operated automatically using PLC and SCADA. 

Biogas from the UASB tanks is delivered to the biogas storage tank prior to delivering to the factory to substitute fossil fuel in the boiler. 

The screw press machine that receives DAF sludge is a multi-disc type with capacity of around 1,400 kg dry solid per hour. This is the latest and most effecient technology nowsaday. The screw press can yield up to 30% dry solid pressed sludge. The benefits of this screw press over conventional filter press and belt press mahines are as follows: 

  • Smaller foot print. 
  • No need for man power to operate the machine or removal of dried sludge. 
  • Less power consumption. 
  • Lower operating and maintenance costs. 

The pressed sludge from this screw press can also be digested using anaerobic digestion process to produce even more biogas. 

Papop is the leading green tech company in Thailand with extensive experience in wastewater treatment, biogas production, water reuse and solar power plant. We provide one stop service for all your renewable and carbon mitigation needs. 

If you are interested in green project like this one, please contact us at LINE @papop or email