The following tables detail pre-treatment issues, their probable causes and possible corrective action that could be undertaken to control issues. Please refer to Applicability of pre-treatments and disinfection techniques to different situations (Table 46) for a summary of water pre-treatment methods and their effectiveness against common water quality problems.
Table 30. Troubleshooting pre-treatment issues
| Probable causes | Preventive measures | Checking preventive measures | Corrective action | |
|---|---|---|---|---|
| What to check | Signs that action is needed | |||
| Observation: No difference in suspended solids between source and filter water samples Possible hazards: Reduced efficacy of pre-treatment |
||||
| Suspended solids smaller than the cut-off size for pre-treatment | Series of filters with lower micron cut-off | Colour Turbidity | Colour and turbidity increase | Replace filter with a lower micron cut-off |
| Damaged pre-treatment system | Regular maintenance | Colour Turbidity | Colour and turbidity increase | Maintain the pre-treatment system |
| Hydraulic overloading | Regular cleaning and replacement | Check hydraulic loading rates | Head loss changing rapidly Frequent backwashing or replacing filters | Clean or replace |
| Observation: Lack of flow Possible hazards: No water for meat chickens |
||||
| Suspended solids, scale or foreign objects in the system | Pre-treatments Scale control Filters | Water flow Water pressure | Blockages | Unblock system |
| Damaged system | Maintenance conducted as soon as issue identified | Water flow Water pressure | Equipment failure | Fix equipment |
| Observation: Effluent water quality changes Possible hazards: Reduced efficacy of disinfection |
||||
| Effluent water quality changes in turbidity and colour | Regular monitoring | Colour Turbidity | Source water quality changes Turbidity increasing rapidly Colour increasing | Increase the sampling frequency of raw water Increase pre-treatment |
| Effluent changes in alkalinity, pH or temperature | Regular monitoring | pH Alkalinity | Scale Lower disinfectant effectiveness | Pre-treat to reduce alkalinity Adjust pH |
