3.5 What are the O&M Requirements?

A skilled full-time operator is needed to operate and maintain the trickling filter, including the following tasks.

Monitoring of organic loading rate

High organic loading rates can plug the filters by thickening the biofilm and blocking the media pores. This reduces wastewater and airflow, causes ponding, and creates anaerobic and smelly conditions. To avoid plugging, the loading rate should be kept within the design limit and washing of the filter media is required.

Inspection of the filter materials for clogging and moisture

• Wash the filter: The sludge on the filter should be washed regularly to avoid clogging and keep the biofilm aerobic. High hydraulic loading rates (flushing doses) can be used to flush the filter. The optimum dosing rates and flushing frequency should be determined from the field operation.
• Keep the filter moist: The packing must be kept moist to prevent the biofilm from drying out. Periods of non-supply to the trickling filter lead to its desiccation and are to be avoided. This may be problematic at night when water flow is reduced or when there are power failures.

Pump maintenance

The operator should inspect the pump for any problems and repair them as soon as possible. The pump is essential for distributing the wastewater over the media and maintaining the hydraulic loading rate.

Pest control

Snails and filter flies can harm the biofilm and reduce the treatment efficiency. Snails can develop in nitrifying filters and feed on the biofilm. Filter flies are small insects that breed in the filter and can pass through the window screens. Both pests can be controlled by backwashing and periodic flooding. Chemical treatments, such as chlorination, copper sulphate, or molluscicides, can also be effective.

Cold weather

Cold weather can cause the filter to freeze and reduce the microbial activity. To prevent this, the filter should be insulated or covered.

For further information, please click on the Materials tab at the top of the page.