Summary
The near-natural slow filtration used for drinking water treatment is notable for its low energy requirement, minimal maintenance costs and low incidence of waste. In addition, the method can be adapted to individual needs and conditions. The aim of the subproject is to verify the extent to which this adaptability can be applied to locations outside Central Europe. To do this, the cleaning capacity of alternative, cost-effective filter materials (recycled glass granulate, coconut fibre, reference sand) was studied in slow filter test systems in the laboratory and on a semi-technical scale. The changed parameters are the temperature (5-10 °C, 20 °C, 30 °C), the filter rate (1 m/d, 2,2 m/d, 3,8 m/d) and the operating method (continuous, intermittent). The surface water used as untreated water has an artificially raised DOC (dissolved organic carbon, range 5-9 mg/l) and ammonium content (range 1-5 mg/l).
Results:
- Recycled glass granulate and coconut fibre can be used as alternative filter materials in slow filtration. However, their respective advantages and disadvantages must be taken into account before use.
- In terms of drinking water regulations and WHO guidelines, under the selected operating conditions limits were exceeded for ammonium, nitrite and manganese. No limits were exceeded for turbidity, nitrate, iron, nickel, copper, zinc and sulphate.
- In outdoor tests, only the coconut fibre filter in continuous operation was capable of obtaining drinking water directly from the untreated water used, and met the WHO standards in terms of the chemical parameters studied.
- The slow sand filter equipped with activated carbon retains pesticide and drug agents. Therefore, activated carbon is suitable as an additional filter material in slow sand filtration for artificial groundwater enrichment.
