Industry best practice manual for water quality management and sterilisation on-farm

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Other metals treatment

Performance goal: Minimise metal contamination in drinking water.
Description: Metals usually occur naturally in small quantities in water. High concentrations of metals in water usually occur from contamination from industrial processes or leaching from water distribution systems.

Acidic water is corrosive and can leach metals from pipes and fixtures (e.g. copper, lead, zinc). It can also damage metal pipes and cause other problems, such as a metallic or sour taste (water with a low pH may contain metals in addition to copper, lead and zinc).
Performance criteria: Metal contamination is controlled.

Best practice levels: copper 0–0.002mg/L, lead 0mg/L, zinc 0–1.5mg/L

Maximum acceptable levels: copper 0–0.6mg/L, lead 0–0.01mg/L, zinc 0–1.5mg/L
Minimum requirements
Measure annually.
If high levels are found, expand the analysis to include: antimony, arsenic, cadmium, chromium–as Cr (VI) and mercury.
If acidifying water:
  • Take care not to corrode metal water pipes and system components, and
  • Locate the acidify point after primary pumps,
  • Make sure peristaltic dosing pump or pump material is resistant to acid corrosion.
  • Best practice options
    If heavy metal contamination has been identified as an issue:
  • increase measuring frequency,
  • identify the source of contamination. (i.e. natural, pipes, soldering, corrosion, acid leaching), and
  • use leaching resistant materials in the water distribution systems.
  • If concentrations are above maximum acceptable levels, apply a pre-treatment. See Table 17 (below) for a comparison of the effectiveness of pre-treatments against metals.

    Table 17. Effectiveness of pre-treatments against metals

    Effectiveness against metalsMetal ions Copper Lead Zinc
    PP filter
    Ceramic filter
    Pleated filter
    Rapid sand filters
    Semi-rapid sand filters
    Slow sand filters
    Centrifugal filtration
    Ion-exchange resinsLMHMHMH
    Chemical coagulatesLLLL
    Lime softeningLLLL
    Chemical oxidation
    Reverse osmosisHHHH
    Electrodialysis reversalLMLMLMLM
    Capacitive deionisationLMLMLMLM
    Membrane capacitive deionisationLMLMLMLM
    Electronic water conditioning
    L: low, LM: low to moderate, M: moderate, MH: moderate to high, H: high, –: N/A
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