Application of wastewater for irrigation is one of the useful approaches to alleviate the shortage of freshwater resources. Although successful implementation of wastewater-use projects depends upon the support of farmers who are affected by the project, few studies have addressed the farmers' attitude towards wastewater use and little is known about Iranian farmers' perception. Therefore, the objective of this study was to investigate farmers' attitude towards wastewater use. It was also intended to detect drivers of perceived economic benefits, and health and environmental risks of wastewater use. A survey of 108 farmers of Shiraz County, selected through a simple random sampling method, identified a number of significant knowledge gaps that currently exist among wastewater users. Furthermore, farmers articulated opposing attitudes for irrigating with wastewater. While farmers realized the contribution of wastewater to fertilize the soil and its reliability as a water resource, they were concerned about its negative impacts on health and environment. Regression analysis illustrated that a complex set of factors significantly influenced perceived risks of wastewater use, among which knowledge, closeness to wastewater canal and value orientation are the most determinant factors. Some recommendations are offered to promote farmers' awareness and attitude about wastewater and reduce its negative impacts.

Introduction

Climate change, water scarcity and quality problems are worldwide phenomena (Clarke, 1993; Keshavarz & Karami, 2014). Reduction of river flows, destruction of water-based ecological systems and depletion of groundwater are occurring in many arid and semi-arid parts of the world (Lamichhane & Babcock, 2013). Dwindling freshwater resource is also the harsh reality of some severely affected drought-prone areas (Keshavarz et al., 2013). To overcome these issues, finding alternative sources of water is perceived by the governments as an essential part of the Sustainable Water Management Scheme (Marlow et al., 2013).

The largest water-consuming sector is agriculture, which makes up 70% of the world's consumption of developed freshwater supplies (Gleick, 2000). Development of irrigation through a more efficient use of water or application of treated wastewater has the potential to save large amounts of freshwater (Pereira et al., 2002). Rough estimates indicate that at least 20 million hectares of agricultural land in 50 countries are irrigated with partially treated and untreated wastewater (Scott et al., 2004; Jimenez, 2008). Especially in lower-income arid and semi-arid countries, irrigation with wastewater is a common practice in peri-urban areas. Low-quality water (i.e. partially treated or untreated wastewater) can reduce crop yield and quality, degrade soil and groundwater quality and destruct the local environment (Mojid et al., 2010). Therefore, successful implementation of wastewater-use projects depends upon the support from the farmers who pay for, and are affected by, the projects (Friedler et al., 2006). In spite of the prevalence of reclaimed wastewater programs for supplying more reliable irrigation water, some use schemes are confronted by opposition from farmers, which results from a combination of prejudiced beliefs, fear, attitudes, lack of knowledge and general distrust (Jeffrey & Temple, 1999; Po et al., 2003; Hurlimann & McKay, 2004; Menegaki et al., 2007; Dupont, 2013). For the purpose of informing strategy and policy, investigating farmers' attitude is imperative.

Few public attitude surveys on the issue of wastewater use can be found throughout the literature (Friedler et al., 2006). Furthermore, almost all the studies have been conducted in the USA, Australia and Western Europe while less information is available regarding the farmers' attitude in other regions (Vo et al., 2014). Farmers' attitude studies are therefore required in different regions and under various environmental and climatic conditions, because of the large variation in culture, climate, water availability, economy etc. Such variability makes the transferability of specific findings and conclusions from one region to another problematic (Friedler et al., 2006).

The available public attitude surveys were accordingly divided into three categories concerning different circumstances (Friedler et al., 2006; Vo et al., 2014). The first category (to which most of the studies belong) dealt with general attitude towards water reuse, not necessarily assigned to any specific, imminent reuse scheme. The second category examined public consultation with people towards actual, forthcoming water reuse projects, while the third reviewed the satisfaction of those who have already experienced the actual use of treated wastewater. For the third category (attitude of real users), there are only limited data (e.g. Marks et al., 2003; Friedler et al., 2006; Hurlimann, 2008). Attitude of wastewater users is not well documented in Iran as yet. Therefore, the aim of this study was to assess the challenges of using partially treated wastewater for irrigation, based on farmers' knowledge and attitude towards this issue. The objectives were to: (a) identify farmers' attitude towards problems and challenges of irrigating with wastewater and (b) investigate the factors that influence farmers' attitude towards use of wastewater for irrigation.

The paper first presents the status of wastewater use in Iran. After that, the health and environmental concerns of wastewater application are explained. The focus then shifts to the survey data and valuation tasks, followed by an analysis of results and concluding remarks.

Status of wastewater use in agriculture: the case of Iran

Iran is a semi-arid country suffering from a severe water shortage. Agriculture as the largest water-consuming sector accounts for 93% of the total water consumption (Ardakanian, 2005), meanwhile only 44% of Iran's agricultural land is irrigated (Food & Agriculture Organization, FAO, 2008) and the rest is rain-fed. The long-term average annual precipitation is in the range of 224–275 mm/year, of which 70% occurs in the northern and western regions of Iran (Forouzani & Karami, 2010). Moreover, Iran is not well-endowed with water; the per-capita water endowment is approximately one-quarter of the world mean value (Alyasin, 2005). At the advent of increased water scarcity, low-quality water warranted attention for agricultural purposes. In Iran, the major source of low-quality water is urban and industrial wastewater. In this regard, 129 wastewater treatment plants (WWTPs) have been established in the last four decades. The treatment plants vary in size from small schemes (i.e. Shiraz, Zanjan and South Khorasan) to large ones (i.e. Tehran and Mashhad) (Tajrishy, 2014). However, the total rate of wastewater treatment is quite low, only accounting for approximately 40% of the total domestic sludge (Tajrishy, 2014). Unfortunately, in some densely populated cities, raw wastewater is used directly for crop irrigation in peri-urban areas (Qishlagi et al., 2008). As the potential of well-planned wastewater treatments for agricultural practices will reach its maximum capacity in the future, WWTPs should gain more support in Iran.

Health and environmental risks of wastewater

About one-tenth of the global crops are irrigated with wastewater, among which only 10% are irrigated with properly treated wastewater (Scheierling et al., 2010). Treated wastewater can supplement necessary nutrients for plants, add organic materials to soil (Horswell et al., 2003; Liu et al., 2005; Candela et al., 2007) and, consequently, provide economic benefits for farmers by reducing fertilizer usage (Chen et al., 2014). On the other hand, wastewater contains a large amount of contaminants that can accumulate in soils and pose a potential risk to soil quality and productivity in the long term (Liang et al., 2014).

The risk associated with the use of wastewater can be reduced by treating the wastewater before it is applied (Hussain et al., 2001; Liang et al., 2014). However, in some developing countries where treatment costs cannot be afforded, wastewater in its untreated or partially treated form is widely used in agriculture (Qishlagi et al., 2008). Thus, many of the compounds such as micro pollutants and nutrients, predominantly nitrogen and phosphorus materials, which can cause eutrophication while being discharged into the environment (Luo et al., 2014; Naughton & Hynds, 2014; Vo et al., 2014), are able to pass through wastewater treatment processes. The release of such contaminants into the environment may have impacts on soil parameters, such as pH, salinity, cation exchange capacity, buffering capacity, and macro- and micronutrients for plant growth (Alvarez-Bernal et al., 2006), thereby affecting soil microbial environments that function in element cycling, pollutant degradation and plant growth (Fatta-Kassinos et al., 2011; Liang et al., 2014). Heavy metals, pathogens and many organic compounds (e.g. pesticides) are also the greatest risks to health (Mokhtari et al., 2012). When farmers work with wastewater, they face multifaceted problems of blistering, skin infection, injuries to hands and lower legs, mosquito nuisance and damage to low-lift pumps due to solid wastes (Mojid et al., 2010). The adverse effects on health from prolonged exposure to many chemical contaminants are also well known (e.g. cancers) (Mokhtari et al., 2012).

Meanwhile, long-term application of treated wastewater may result in nutrients and heavy metal accumulation in the soil to toxic levels (Sharma et al., 2007). Crops raised on the metal-contaminated soil also accumulate metals in excessive quantities and cause health problems to human beings and animals consuming such metal-rich plants (Qishlagi et al., 2008). On the other hand, application may contribute to a nitrate surplus that may be leached towards the lower horizons, causing its accumulation in the groundwater and therefore leading to nitrate pollution (Fatta-Kassinos et al., 2011). Change in the basic physiochemical properties of soil (soil quality degradation) is another negative impact of continuous use of wastewater in agricultural lands (Chen et al., 2004).

Material and methods

Study area

This study was conducted in Shiraz County. Shiraz city is located in the south-west of Iran with around 1.3 million inhabitants, which makes it one of Iran's five largest cities. This county with widespread agricultural, horticultural and animal husbandry activities has experienced great water scarcity in the last two decades. In order to relieve the problem of insufficient irrigation water, the city authorities have conducted major investments in wastewater treatment plants. Presently, the inflow of Shiraz Wastewater Treatment Plant (SWWTP) is about 1,000 l/s, which corresponds to around 500,000 of the population. The average inlet flow rate of SWWTP is about 930 l/s and it is expected to provide about 29.5 MCM1/year of water for irrigation (Baghapour et al., 2013). From 2004, the farmers of Gerdkhoon, Kooshkak, Shams Abad, Eghbal Abad, and Khaljooy villages have frequently used partially treated wastewater for irrigation purposes.

Sampling and survey instrument

A multi-stage, stratified random sampling technique was used to select a sample of farmers who applied treated wastewater for irrigating agricultural lands. The sample size (n = 108) was determined based on a formula suggested by Krejcie & Morgan (1970). Initially, the peri-urban areas were classified into five strata (i.e. Gerdkhoon, Kooshkak, Shams Abad, Eghbal Abad, and Khaljooy). A proportional sample was then randomly selected from each stratum.

A questionnaire was developed for the survey to be used for the interviews. The face validity of the scales applied to the study were confirmed by a panel of experts, and a pilot study, involving 30 farmers using wastewater for irrigation, was conducted in Marvdasht County to evaluate the instrument. To measure farmers' attitude towards wastewater use in agriculture, theories of Planned Behavior (Ajzen, 1991), Value-Belief-Norm (Stern et al., 1999), the Population, Organization, Environment and Technology (POET) (Duncan, 1964), and altruistic behaviors (Schultz & Boehnke, 2004) were considered. Table 1 defines study variables and their Cronbach's alpha reliability coefficient.

Table 1.

Study variables.

Variables Definition Cronbach's alpha coefficient 
Knowledgea Farmers' awareness of wastewater use, health and environmental issues 0.64 
Attitude towards risks Economic benefitsb The farmers' economic gain from wastewater-use schemes 0.61 
Environmental risksb The extent of the wastewater risks for the environment 0.79 
Health risksb The extent of health risks associated with wastewater-use 0.62 
Value orientation Egoisticb Values focusing on maximizing individual outcomes 0.79 
Social-altruisticb Values reflecting concerns for the welfare of other people 0.77 
Biosphericb Values emphasizing the environment and the biosphere as a whole 0.84 
Human ecology concerns Population contextb Attitude towards changes in mortality, fertility and migration rate of the population that increases the need for using wastewater 0.61 
Organizational contextb Attitude towards the capability of the relevant organizations in maintaining a high effluent quality 0.67 
Environmental contextb Attitude towards the role of natural environment in shaping farmers' wastewater-use behavior 0.61 
Technological contextb Attitude towards mechanical technologies designed to provide low-cost treated wastewater for irrigation purposes 0.66 
Public acceptabilityc Attitude towards public acceptance to develop wastewater-use schemes 0.67 
Responsibilityc Farmers' perception of their degree of being responsible, answerable or accountable for things within their power, control and management 0.72 
Risk perceptionc The subjective judgment that farmers make about the characteristics and severity of a risk 0.77 
Trustc Farmers' opinion regarding whether the authorities support the wastewater-use schemes 0.76 
Age The age of household head  
Education The years of formal education of farmer  
Productivity Crop yield (tons per hectare of each cultivated crop)  
Farm size Land area (hectare)  
Closeness to canal Distance from wastewater canal (kilometer)  
Variables Definition Cronbach's alpha coefficient 
Knowledgea Farmers' awareness of wastewater use, health and environmental issues 0.64 
Attitude towards risks Economic benefitsb The farmers' economic gain from wastewater-use schemes 0.61 
Environmental risksb The extent of the wastewater risks for the environment 0.79 
Health risksb The extent of health risks associated with wastewater-use 0.62 
Value orientation Egoisticb Values focusing on maximizing individual outcomes 0.79 
Social-altruisticb Values reflecting concerns for the welfare of other people 0.77 
Biosphericb Values emphasizing the environment and the biosphere as a whole 0.84 
Human ecology concerns Population contextb Attitude towards changes in mortality, fertility and migration rate of the population that increases the need for using wastewater 0.61 
Organizational contextb Attitude towards the capability of the relevant organizations in maintaining a high effluent quality 0.67 
Environmental contextb Attitude towards the role of natural environment in shaping farmers' wastewater-use behavior 0.61 
Technological contextb Attitude towards mechanical technologies designed to provide low-cost treated wastewater for irrigation purposes 0.66 
Public acceptabilityc Attitude towards public acceptance to develop wastewater-use schemes 0.67 
Responsibilityc Farmers' perception of their degree of being responsible, answerable or accountable for things within their power, control and management 0.72 
Risk perceptionc The subjective judgment that farmers make about the characteristics and severity of a risk 0.77 
Trustc Farmers' opinion regarding whether the authorities support the wastewater-use schemes 0.76 
Age The age of household head  
Education The years of formal education of farmer  
Productivity Crop yield (tons per hectare of each cultivated crop)  
Farm size Land area (hectare)  
Closeness to canal Distance from wastewater canal (kilometer)  

aMeasured by an ordinal variable ranging from 0 (false) to 2 (true).

bMeasured by an ordinal variable ranging from 1 (very low) to 5 (very high).

cMeasured by an ordinal variable ranging from 1 (strongly disagree) to 5 (strongly agree).

Results and discussion

Farmers knowledge about wastewater use

Only 50.9% (n = 55) of farmers knew about laws and regulations for the safe use of wastewater in agriculture. Furthermore, a slight majority of farmers (68.5%, n = 74) recognized the fertility values of wastewater, but most of them (69.4%, n = 75) had an inadequate insight into the nitrogen (N), phosphorus (P) and potassium (K) contents of irrigation water. About 60.2% (n = 65) of farmers were familiar with negative impacts of wastewater on soil quality. Also, only 39.8% (n = 43) of respondents knew about the long-term effects of wastewater irrigation on heavy-metal contents in soils.

Although farmers had years of experience in wastewater application, they had very little knowledge of its health risks. In all, 23.2% (n = 25) and 12.0% (n = 13) knew about the negative impacts of wastewater on farm workers and consumers' health, respectively, while a majority of respondents (89.8%, n = 97) acknowledged the lack of hygienic safety of vegetable and other crops if irrigated with untreated wastewater.

It seems that insufficient knowledge about nutrient contents of wastewater and the health risks associated with the use of this source of water is due to inadequate dissemination of information for the farmers. In the absence of well-managed public information programs, learning from experience and communication with other farmers are the most preferable sources for getting information about wastewater. Findings showed that the majority of farmers (more than 80%) never used mass media (i.e. radio and television) to collect information about wastewater. Also, only 51.9% of farmers were able to participate in the agricultural extension courses. They believed that the effectiveness of extension services for improving information about wastewater has been low.

Farmers' attitude towards economic, environmental and health risks or benefits of wastewater use

Economic benefits and risks of wastewater

Farmers in the study area mainly irrigated wheat and barley with wastewater. Although Shiraz Health Organization prohibits the use of wastewater for irrigating vegetables and summer crops, some farmers used wastewater for irrigation of maize, potato, vegetables and some other crops.

Since Shiraz County has been confronting groundwater degradation and prolonged water scarcity, use of wastewater was a common practice by almost all farmers in peri-urban areas who have limited access to freshwater. Therefore, the cultivation areas under winter crops were greater than they had been in the past (during drought years without the access to wastewater). However, the farmers did not significantly increase the cultivation areas for summer crops due to the governmental regulations that limit using wastewater for summer crops because they are mainly consumed uncooked.

Farmers experienced significant reduction in yields of wheat, barley and millet by irrigation with wastewater compared to the time they used freshwater (Table 2). Although wastewater contained a high concentration of salt, farmers were not motivated to reduce their wastewater use because of its reliable availability for winter crops almost at no cost. Also, every farmer used a surface flood irrigation system in their farm.

Table 2.

Crop yields (tons per hectare) under irrigation with wastewater (WW) and freshwater (FW).

Crops Irrigated by FW Irrigated by WW t-test Significance 
Wheat 6.25 5.20 7.202 0.001 
Barley 4.75 4.26 5.240 0.001 
Millet 4.71 3.64 3.322 0.006 
Crops Irrigated by FW Irrigated by WW t-test Significance 
Wheat 6.25 5.20 7.202 0.001 
Barley 4.75 4.26 5.240 0.001 
Millet 4.71 3.64 3.322 0.006 

A slight majority of farmers believed that the gradual increase of their land's fertility is due to irrigation with wastewater. Although they could not quantify the fertilizer contribution of wastewater, most of them applied fewer fertilizers when wastewater was used. Therefore, wastewater reduced their production costs by saving fertilizers.

In order to obtain information about determinants of farmers' attitude towards economic benefits and risks of wastewater, a multiple linear regression model was used. Independent variables included into the model are described in Table 1. The results showed that the specified variables explained 48% of the total variance in attitude towards economic benefits and risks of wastewater. The standardized regression coefficients indicated that farm distance to the wastewater canal (closeness) was the most important determinant of economic benefits of wastewater, followed by productivity and egoistic value orientation (Table 3).

Table 3.

Determinants of farmers' attitude towards economic benefits and risks of wastewater.

Independent variables† Standardized coefficients (Beta) Sig. 
Closeness to canal 0.339 0.001 
Productivity 0.319 0.001 
Egoistic value orientation 0.282 0.004 
Independent variables† Standardized coefficients (Beta) Sig. 
Closeness to canal 0.339 0.001 
Productivity 0.319 0.001 
Egoistic value orientation 0.282 0.004 

†For definition of variables, see Table 1.

F =16.102, Sig. F =0.0001, R2 = 0.48.

The farms close to the wastewater canal had more reliable wastewater for irrigation than those which were more distant. Some waterborne fertilizers had also settled as wastewater passed over some distance, consequently, longer distances increased the money spent on fertilizers.

Results revealed that productivity (i.e. barley yield) has significantly influenced an attitude towards economic benefits (Table 3). The peri-urban farmers articulated mixed experiences on the quantity of barley yields obtained under irrigation with wastewater. Some farmers who had access to the reliable wastewater claimed that barley grew well when irrigated with wastewater and resulted in a higher yield compared to that irrigated with freshwater, while the others reported getting reduced yields. This means that supplying more reliable irrigation water would lead to increased productivity of barley yield.

The findings also suggest that the value orientation (i.e. egoistic belief) has a significant effect on attitude towards economic benefits of wastewater (Table 3). While at the advent of increased water scarcity, a common type of environment-friendly behavior is reducing irrigation water consumption, the egoistic farmers exhibited a too-high willingness to increase their cultivation area. Increasing cultivation area inadvertently limited access of other farmers to wastewater. The egoistic farmers were also willing to donate a piece of their land to canal construction if the developed canal provides private benefits.

Environmental risks of wastewater

Wastewater use in agriculture can create various environmental risks in the form of soil and groundwater degradation and aquatic life destruction. As illustrated in Table 4, farmers had contrasting attitudes towards the quality of soils irrigated with wastewater. Some (53.7%) recognized high or very high degradation of soil quality (i.e. salinity) due to irrigation with wastewater, while the others (46.3%) did not perceive any problem with the quality of the land. Differences in perceived soil quality were the result of the duration of wastewater application. Long-term use of wastewater can increase the amount of salts and heavy metals into the soil and reduce productivity.

Table 4.

Perceived negative impacts of wastewater irrigation on environment.

  Environmental risks
 
Elements Very low Low High Very high 
Reduced soil quality 13(12.0%) 37(34.3%) 46(42.6%) 12(11.1%) 
Increased environmental degradation 34(31.5%) 47(43.5%) 21(19.4%) 6(5.6%) 
Degraded groundwater quality 52(48.1%) 41(38.0%) 15(13.9%) – 
  Environmental risks
 
Elements Very low Low High Very high 
Reduced soil quality 13(12.0%) 37(34.3%) 46(42.6%) 12(11.1%) 
Increased environmental degradation 34(31.5%) 47(43.5%) 21(19.4%) 6(5.6%) 
Degraded groundwater quality 52(48.1%) 41(38.0%) 15(13.9%) – 

While extermination of fish and other aquatic habitats in the wastewater canals, dissolved oxygen depletion, eutrophication and foaming were reported at some locations, 75% of farmers (Table 4) acknowledged that wastewater did not pose a serious threat to the environment. Moreover, only 13.9% of farmers experienced deterioration of groundwater quality (Table 4). During the recent drought, most of the traditional groundwater irrigation systems (qanats) and shallow or deep wells have dried up, and farmers' access to groundwater has significantly reduced. Therefore, most farmers lack the knowledge to judge groundwater contamination. However, local newspapers often reported quality problems of extracted groundwater.

The same independent variables were used in the regression analysis to identify factors influencing farmers' attitude towards environmental risks (See Table 1 for description of variables and their measurements). As shown in Table 5, 65% of the total variance in attitude towards environmental risks was explained by the independent variables. From Table 5, it is apparent that the variable ‘responsibility’ is the main predictor of ‘perceived environmental risks’, followed by knowledge, closeness to canal, egoistic value orientation, and population context.

Table 5.

Determinants of farmers' attitude towards environmental risks of wastewater.

Independent variables† Standardized coefficients (Beta) Sig. 
Responsibility −0.595 0.001 
Knowledge −0.313 0.001 
Closeness to canal −0.229 0.014 
Egoistic value orientation 0.203 0.015 
Population context −0.167 0.040 
Independent variables† Standardized coefficients (Beta) Sig. 
Responsibility −0.595 0.001 
Knowledge −0.313 0.001 
Closeness to canal −0.229 0.014 
Egoistic value orientation 0.203 0.015 
Population context −0.167 0.040 

†For definition of variables, see Table 1.

F =25.863, Sig. F =0.0001, R2 = 0.65.

To confront the challenge of the increasing wastewater demanded for agriculture, some farmers adopted water-stress-tolerant crops, crop rotation and reduced irrigation frequency to meet the water needs of other farmers and avoid long-term damage to the soil structure. Farmers who accepted a proactive moral responsibility for the environment believed that adherence to good irrigation and farming practices is essential to avoid adverse environmental effects.

As illustrated in Table 5, the knowledge of wastewater use has an important influence on perceived environmental risks. Knowledgeable farmers declared that upon increased rates of salinization and waterlogging, soil pollution had occurred. Therefore, it is imperative to pay adequate attention to leaching and draining requirements. Moreover, dissemination of more wastewater-related information is needed to enhance farmers' knowledge about risks of wastewater use.

According to Table 5, distance from desalination plant has significantly influenced attitude towards environmental risks. Farms located close to wastewater main canals receive water with a relatively high content of impurities, among which salts are the most important factor. Therefore, the quality of these lands will reduce, gradually. Meantime, heavy metals and salts settle as wastewater passes over distance so that farms at the far end of the canal receive wastewater with lower impurity and fewer environmental threat exposures.

Table 5 revealed that egoistic value orientation played an important role in determining attitude towards environmental risks of wastewater. Egoistic farmers were concerned more about their own benefits and less about environmental impacts. While the long-term application of partially treated wastewater can degrade soil quality, they insisted on increasing the cultivation area only to maximize their short-term profits. Additionally, the drying up of private boreholes and lack of adequate access to groundwater reduced their concerns about groundwater quality.

The findings showed that population context has significant influences on attitude towards environmental risks of wastewater (Table 5). In the context of water scarcity, farmers often have no alternative solution but to use partially treated wastewater. With such limited access to water, farmers are forced to reduce their requirements. However, this unwritten regulation was not observed by all farmers and some used as much wastewater as they could. Therefore, extensive use of wastewater contributed to soil degradation.

Health risks of wastewater

Various types of enteric pathogens can be found in wastewater, including viruses, bacteria, protozoa and helminths. These contaminants can cause great health concerns for people working in wastewater-irrigated fields or consuming wastewater-irrigated foods, especially when eaten uncooked (e.g. salad crops and some vegetables). Therefore, farmers were asked to assess the actual health risks of wastewater application.

Although critical review of the epidemiological evidence of partially treated wastewater health effects (Blumenthal & Peasey, 2002) shows that the risk of bacterial and viral enteric infections is significant for both humans and animals, the majority of the farmers (89.8%; Table 6) perceived the possibility of viral, bacterial and protozoan infection through consuming wastewater-irrigated crops to be low and very low.

Table 6.

Farmers' perceived health risks of wastewater.

  Health risks
 
Wastewater increases Very low Low High Very high 
Viral, bacterial and protozoan infection among consumers 52(48.1%) 45(41.7%) 9(8.3%) 2(1.9%) 
Prevalence of infectious diseases 27(25.0%) 64(59.3%) 15(13.9%) 2(1.9%) 
Toxicity of crops and vegetables 3(2.8%) 14(13.0%) 85(78.7%) 6(5.6%) 
Health risks for farmers and their families 54(50.0%) 42(38.9%) 9(8.3%) 3(2.8%) 
  Health risks
 
Wastewater increases Very low Low High Very high 
Viral, bacterial and protozoan infection among consumers 52(48.1%) 45(41.7%) 9(8.3%) 2(1.9%) 
Prevalence of infectious diseases 27(25.0%) 64(59.3%) 15(13.9%) 2(1.9%) 
Toxicity of crops and vegetables 3(2.8%) 14(13.0%) 85(78.7%) 6(5.6%) 
Health risks for farmers and their families 54(50.0%) 42(38.9%) 9(8.3%) 3(2.8%) 

Many bacterial diseases, such as diarrhea and cholera, can spread by wastewater use in agriculture and transmit to those consuming wastewater-irrigated crops and raw vegetables (Toze, 2006; Qishlagi et al., 2008; Scheierling et al., 2010). As indicated in Table 6, there was less compelling evidence about the transmission of diseases to farmers, their families and crop consumers. It is not surprising to find a low perceived health risk from viruses, bacteria and protozoa, because most of the farmers did not have deep knowledge about health risks of wastewater (for more information, please see Section 3.1).

Health risks from chemicals arise from heavy metals and many organic compounds (such as pesticides), which accumulate in the soil to toxic levels. Crops and vegetables raised on the contaminated soils also accumulate chemicals in excessive quantities that cause health problems. The majority of farmers (84.3%; Table 6) asserted toxicity of crops and vegetables irrigated with wastewater. Field observation revealed that the outbreak of some diseases in 2004 in Shiraz, which was attributed to consumption of wastewater-irrigated vegetables, increased farmers' awareness about chemical health risks.

In the case of flood or furrow irrigation, farmers are at high risk because they have intensive contact with wastewater, as they do most of the field work manually and barefoot. Findings indicated that farmers did not perceive that wastewater irrigation poses significant health risks to them or their families (Table 6).

Regression analysis was used to predict farmers' attitude towards health risks (see Table 1 for description of variables and their measurements). As shown in Table 7, the specified variables explained 47% of the total variance in attitude towards health risks. Results revealed that, on the whole, closeness to wastewater canal, biospheric value orientation, and knowledge have significant effects on perceived health risks from wastewater use.

Table 7.

Determinants of farmers' attitude towards health risks of wastewater.

Independent variables† Standardized coefficients (Beta) Sig. 
Closeness to canal 0.320 0.001 
Biospheric value orientation −0.271 0.004 
Knowledge −0.262 0.008 
Independent variables† Standardized coefficients (Beta) Sig. 
Closeness to canal 0.320 0.001 
Biospheric value orientation −0.271 0.004 
Knowledge −0.262 0.008 

†For definition of variables, see Table 1.

F =16.043, Sig. F =0.0001, R2 = 0.47.

Based on the findings, distance from wastewater canal has a significant effect on attitude towards health risks (Table 7). Farmers at the far end of the canal who are provided with unreliable wastewater showed less concern about health impacts of wastewater.

According to Table 7, biospheric value orientation significantly influences attitude towards health risks and thus affects perceptions of wastewater use. Farmers motivated by biospheric values applied wastewater based on moral principles that incorporate health concerns about humans, plants and animals. These farmers mainly set up their irrigation activities on the basis of safe wastewater use in order to reduce potential health risks. The findings also suggest that health concerns about wastewater are significantly affected by knowledge (Table 7). Although most of the farmers have inadequate knowledge about health risks, farmers who knew the potential health hazards appeared to perceive such risks to be high. Even though some farmers were familiar with negative health impacts of wastewater, they continued using it since there were no other accessible water sources for agriculture.

Conclusion

The aim of this research was to investigate farmers' attitude towards wastewater use. Few public attitude surveys on the issue of wastewater use are conducted worldwide. Similarly, the attitude of Iranian wastewater users has not yet been investigated. This paper addresses this gap. Although it focuses on Iran, the implications for wastewater-use policy arising from this research can be widely applied. Findings revealed that farmers realized the contribution of wastewater to soil fertility and its reliable availability, but they did not perceive any other economic beneficial aspect of wastewater. Although farmers generally viewed wastewater unfavorably, they often had no alternative but to use partially treated wastewater because of unavailability of freshwater.

Some farmers were extremely concerned with wastewater negative impacts on health and environment. In this respect, appropriate treatment of wastewater for viral, bacterial and chemical risks, before application in the fields, and other field-protective measures such as wearing shoes and gloves and reducing cultivation of crops that are consumed fresh (e.g. vegetables) are highly recommended. In order to reduce farmers' vulnerability to health and environmental risks of wastewater, agricultural interventions should be combined with effective social support services such as efficient knowledge management systems and regulations for wastewater application.

Through the regression analysis, this research also assessed determinants of farmers' attitude towards wastewater use. Results implied that farmers' perceptions of economic benefits, health and environmental risks are products of a complex set of factors, among which knowledge, farm distance to wastewater canal (closeness), and value orientation are the most important factors. Findings indicated that a widespread attitude among farmers was that using wastewater for irrigation poses a significantly smaller threat to public health and the environment than research suggests. Therefore, a number of significant knowledge gaps exist among wastewater users. To fill the gaps and achieve comprehensive health and environment protection for farmers, consumers and the natural environment, it is imperative that farmers recognize the risks. Without risk awareness, it will be very difficult to promote a behavior change towards safer practices (Keraita et al., 2010). Therefore, agricultural extension services have great roles to play in improving safe application of this inevitable source of irrigation water. Farmers' wastewater irrigation practices were influenced by perceived economic, health and environmental concerns. It is suggested that information regarding pollution and the degree of health and environmental risks associated with wastewater be disseminated through mass media and extension services. While extension services enhance the awareness of farmers regarding wastewater, most farmers made decisions based on their own limited knowledge. Improved extension services are also necessary to reduce the negative consequences of wastewater.

Results revealed that having adequate access to reliable wastewater provided economic benefits for farmers whose farms were located close to the wastewater canal, while the others were less satisfied with economic advantages of wastewater. Some intervention is needed to ensure equitable distribution of wastewater. Moreover, farms located close to the wastewater canal received water with higher impurity and, consequently, were more exposed to environmental threats. Therefore, advanced technologies should be applied in order to increase the quality of wastewater and reduce environmental risks. This study also showed that egoistic and biospheric value orientations contributed significantly to the explanation of farmers' attitude towards wastewater use. Results revealed that perception about wastewater can be promoted by strengthening farmers' values, particularly their biospheric values. Although changing farmers' values is difficult, it is possible to motivate them to act more upon their biospheric values and prioritize pro-environmental attitudes and behaviors under the conditions in which farmers have to use wastewater.

1

Million cubic meters.

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