Shed issues: biofilm build-up

Table 40. Troubleshooting biofilm build-up

Operational monitoring
Parameter	Target criteria	Critical limits	Monitoring method
Escherichia coli	0CFU/ml	Specific chlorine residual set to achieve a minimum contact time requirement based on maximum flow and minimum storage times.	Online, continuous chlorine residual analyser, flow and pH. 24-hour monitored alarms on residual monitoring, pH and disinfectant dosing equipment.
Disinfectant residual	1–2ppm
Hardness	0–100mg/L	Scale build-up Drinker blockages Coolers clogged with mineral build-up	Online, continuous flow and pH. Regular monitoring with an on-farm test strip. Laboratory analysis. Visual inspection of water pipes and drinkers. Appropriate electronic or hard copy monitoring records.
Calcium	0–60mg/L
Magnesium	0–14mg/L
Sulphates	0–40mg/L
Iron	0–0.2mg/L
Manganese	0–0.01mg/L
Corrective action Breaches in critical limits or target criteria should result in any of the operating procedures below as necessary: Related to the disinfectant residual: inspect and calibrate equipment adjust the flow rate adjust the disinfectant dose or feed point carry out additional monitoring, increase sampling and testing recalculate contact time values implement unplanned maintenance procedure secondary or booster disinfection use alternative supply or divert water engage backup equipment plant automatic shutdown implement emergency response record actions to be taken and report (internally or externally as required). Scale / mineral component of biofilm: conduct an acid treatment flush water lines more regularly water could be acidified for iron, manganese and sulphates scale use an oxidation and filter pre-treatment for low to moderate scale use an electronic descaler iron exchange could be used for moderate to high levels of scale build-up reverse osmosis could be used for high levels of scale build-up. Microbial component of biofilm: identify microbes use a disinfectant that is effective against the specific microbes identified sanitise water lines.
Verification Calibration and maintenance of equipment Drinking water quality monitoring Increase the frequency of monitoring Satisfactory production Evaluation and audit

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