The biofilm wastewater treatment plant (WSB clean) is designed for a kindergarten (50 PE) to replace an existing treatment plant (old septic tank system without biological treatment). WSB clean is a pure biofilm technology – it used a specifically developed carrier material and is designed to treat domestic wastewater in 3 steps: 

• Incoming wastewater travels by gravity through the pretreatment step where coarse particles settle.
• Preprocessed wastewater is now fed into the biological stage, which contains the specially designed plastic carrier media. Microorganisms settle on the media and consume the organic material in the wastewater. Oxygen is needed for the biological cleaning process.
• The final clarifier collect and transfer the secondary sludge back to the sludge storage. From the clarifier, the biologically cleaned wastewater is ready to be discharged back into the environment.

The objective of the two-year operation period of the pilot plant is the adaptation of this flexible technology to the varying sewage loads under extreme climatic conditions, thereby achieving better treatment results than the existing waste water treatment plant. The treatment process is optimized for low energy consumption and minimal operating cost. The trial results will be implemented in the basic design of a standardized series for single houses and group solutions ranging from 5 to 5.000 PE. Specific process benefits include:

• Media is self-cleaning and never has to be replaced
• Robust system able to handle shock loading and extremely long periods of low loading
• Low sludge generation
• Low consumption of energy and minimal operating costs
• Nitrification at temperatures below 12°C
• Simultaneous nitrification and de-nitrification of at least 30 to 50 %

Since its commissioning, the pilot plant in Orkhon soum has been a point of interest for a lot of experts, authorities and visitors, including the Mongolian Minister of Nature, Environment and Tourism. Interests of transfer and implementation of the WSB System in the private and public sector in Mongolia are very high. Ministry of Road, Transport and Urban Infrastructure will standardize the technology for the implementation in other rural regions of Mongolia currently.