Irrigation water disinfestations

Abstract: Irrigation with untreated or low quality water often disperses many infectious diseases. In Sweden, 90 to 99.9% reduction of microorganisms in the water can be achieved by waste water treatment but potential risk of high number of sewage, substantial loads of pathogens could still remain. The main objective of this work was to observe the irrigation water quality at Norrvidinge gård located in Kävlinge community, Scania. Advanced oxidation technology (AOT, Wallenius Water AB, Stockholm, Sweden) was employed in the irrigation pipeline and three disinfestation treatments named as 'stationary- AOT', 'mobile- AOT' and 'combined- AOT' was used for water disinfestations. Water samples were taken for investigation at ten occasions during the season 2007. Presence of elevated numbers of heterotrophic organisms was common phenomenon in the water samples. The hygienic quality of the investigated water was good. Coliform bacteria and Escherichia coli loads were found very low in the samples comparing to the World Health Organization (WHO) standard for irrigation water or German standard for irrigation water (DIN 1965). Advanced oxidation Technology (AOT) was found effective for the reduction of microbial loads and placement of the AOT-device within the pipeline system was essential. Investigated organic compounds (total organic carbon, TOC; chemical oxygen demand, COD; total nitrogen, TN and total phosphate, TP) and inorganic compounds (ammonium-nitrogen, NH4-N; nitrate-nitrogen, NO3-N; phosphorus, P; and sulphur, S) did not seem to be affected by the disinfestation treatments. The amount of the organic compounds in the sample water was much lower compared to the standard value. Measurements of the electrical conductivity and pH confirm the non-saline character of the irrigated water.