Microbial Risk Assessment using E. coli in UV Disinfected Wastewater Irrigation on Paddy

Abstract

Water stress has become a major concern in agriculture. Korea suffers from limited agricultural water supply, and wastewater reuse has been recommended as an alternative solution. A study was performed to examine the effects of microorganism concentration in the ponded-water of a paddy rice field with reclaimed-water irrigation for evaluating the microbial risk to farmers and neighborhood children. Most epidemiological studies were performed based on an upland field, and they may not directly applicable to paddy fields. Beta-Poisson model was used to estimate the microbial risk of pathogen ingestion. Their risk value increased significantly high level after irrigation and precipitation. It implies that agricultural activities such as plowing, and fertilizing, and precipitation need be practiced a few days after irrigation considering health risks. The results about field application of the microbial risk assessment using E. coli showed difference according to monitoring time and treatment plot. Result of the microbial risk assessment showed that risk values of groundwater and reclaimed secondary wastewater irrigation were lower than directly use of wastewater treatment plants' effluent. This paper should be viewed as a first step in the application of quantitative microbial risk assessment of E. coli to wastewater reuse in a paddy rice farming.

Study of Reclaimed Water Reuse Standards and Prospects in Irrigation in Egypt

“…In fact, the use of wastewater for irrigation purposes can pose significant risks to farmers and more generally to the public health. There are many risk factors associated with the reuse of wastewater in irrigation such as the accumulation of the substances in soil voids which lead to a decrease in the crop growing, causing the microbe infection and soil deterioration [10]. The indirect reclaimed water reuse in irrigation occur when the cultivated land is far from the effluent source.…”

Irrigation Water Quality Standards for Indirect Wastewater Reuse in Agriculture: A Contribution toward Sustainable Wastewater Reuse in South Korea

“…This means that additionally treated effluent after the regular WWTP processes meets the requirement for irrigation water [17]. However, when irrigating with treated wastewater diluted with stream water, the E. coli concentration exceeded the enteric disease risk value of 10´4, and this has been reported to cause infection to farmers [17]. Yoon et al [64] reported that the above risk can be drastically mitigated when farming activities take place 24 h after irrigation.…”

“…Through QMRA of the E. coli concentration of paddy rice irrigation water, it was examined that the human health risk is very low when irrigating reclaimed wastewater. This means that additionally treated effluent after the regular WWTP processes meets the requirement for irrigation water [17]. However, when irrigating with treated wastewater diluted with stream water, the E. coli concentration exceeded the enteric disease risk value of 10´4, and this has been reported to cause infection to farmers [17].…”

“…When using treated wastewater for irrigation, water quality must be strictly controlled considering factors such as the possible accumulation of substances which are harmful for crop growth, the potential damage to soil by the transformation of its physical and chemical characteristics [15,16], and microbe infection [17,18]. Using diluted treated wastewater could somewhat mitigate the side effects but nonetheless cannot prevent it from damaging the commercial value of crops.…”

Aplicação da metodologia de análise de perigo e pontos críticos de controle na disposição de efluentes tratados em solos tropicais e seu potencial uso agrícola

“…Os valores situaram-se na faixa de 4,00 a 10,00 mgP-PO4 coli inferiores a 10 -4 , em cenários de ingestão de 100 mg/dia de solo para adultos e 200 mg/dia para crianças. RHEE et al (2009), obtiveram um risco anual de infecção por este patógeno entre 10 -3 e 10 -5 em águas para irrigação, valores inferiores aos apresentados neste estudo, já ao final do tratamento primário. SEIDU et al (2008), constataram a concentração de ovos de Ascaris na água de irrigação na mesma ordem de magnitude descrita no presente estudo ~10 -2 .…”