Abstract
Context:
Due to water scarcity, wastewater is used in agriculture in peri-urban areas.
Aims and Settings:
We aimed to assess the hazards associated with wastewater farming and develop an incremental improvement plan for the sanitation system of wastewater use for agriculture using Sanitation Safety Planning (SSP) in Bangalore urban district, India.
Methods:
Interviews and observations were conducted among 100 farmers in the Mugalur Gram Panchayat area.
Results:
Direct ingestion and ingestion after contact with wastewater due to inadequate hand hygiene are the routes of contact with wastewater. The control measures followed in the community are the cultivation of crops, which do not have direct contact with wastewater, furrow and drip irrigation, and restricted irrigation. Methods to mitigate the hazards are the provision of interval between final irrigation and consumption,washing of produce with freshwater before transportation to market, and hygienic cooking.
Conclusion:
Occupational hazards and risks associated with wastewater farming can be mitigated through the adoption of locally acceptable preventive measures.
Keywords: Agriculture, farmers, occupational hazards, risk mitigation, sanitation, wastewater
INTRODUCTION
Wastewater contains municipal waste, which includes domestic effluent consisting of black water (containing human excreta) and gray water (from kitchens and bathing), water from commercial establishments and institutions, industrial effluents, stormwater, and other urban runoff.[1] The pollutants and contaminants in wastewater include plant nutrients, pathogenic microorganisms, heavy metals, organic pollutants, biodegradable organics, and micro-pollutants.
Increasing population density in urban areas in India compromises the provision of safe water and sewage treatment by the concerned authorities.[2] Hence, most of the wastewater in urban areas is untreated. This untreated wastewater is often used informally in agriculture due to water scarcity. At times, the yield of crops might be more with wastewater as compared to freshwater, owing to the nutrients such as nitrogen, phosphorus, and potassium present in it, hence reducing the need for the use of fertilizer. However, the disadvantage of these nutrients in wastewater is that the nutrients might be in excess or deficient in wastewater. Despite this, wastewater use in agriculture offers higher urban agricultural production and perennial water supply, thereby contributing to food security and income generation.[3]
In the city of Bangalore, the treatment capacity of wastewater is less than 50% of the amount generated.[4] The South Pennar River known as Dakshina Pinakini flows through the Bengaluru District. Due to rapid urbanization and industrialization in Bangalore, partially treated and untreated wastewater is discharged into the river, which has become perennial due to the drainage of wastewater into it.[5]
Sanitation Safety Planning (SSP) is a “risk-based management tool” useful for sanitation systems. It assists us in identifying and managing health risks in a sanitation chain and thereby guides us in minimizing adverse health impacts and promoting health.[6]
This study aimed to apply the World Health Organization (WHO)’s SSP guide to the sanitation system of wastewater use for agriculture, assess the hazards, and thereby develop an incremental improvement plan for the sanitation system.
METHODS
Study setting
The Mugalur Gram Panchayat area is situated in the Anekal Taluk, Bengaluru Urban District. The Gram Panchayat is the main administrative authority. Mugalur Village is in close proximity to the extended city of Bengaluru and can be characterized as a peri-urban community with agriculture being one of the predominant occupations. This Gram Panchayat area comprises the following villages, namely Mugalur, Banahalli, Mattanahalli, Kugur Madappanahalli, and Pandithana Agrahara, which utilize the water from River Dakshina Pinakini for farming. The study area is affected by the urbanization of surrounding areas. The river having turned into a wastewater stream, reduction in green spaces, and failure of monsoons are crises faced by the study area. Currently, groundwater sourced through bore wells is the potable water source for the study area.
Ethical approval
The study was conducted after obtaining the ethical approval of the Institutional Ethics Committee (IEC) of St. John’s National Academy of Health Sciences, Bengaluru. The study reference number for the IEC is 162 / 2016. The support of the Mugalur Gram Panchayat office and Sarjapura Primary Health Centre (concerned primary health center) was sought for the study. The cataloging of farmers practicing wastewater farming in the study area was done by a local farmer who was recruited in our study as a field assistant. Each farmer was provided a subject information sheet, and written informed consent was obtained before the interview.
Quantitative methods
A total of 100 farmers practicing wastewater farming were interviewed for the quantitative component of the study. The tools used in the study were designed by the investigators based on their field experiences and knowledge of Resource Recovery and Reuse (RRR) in urban ecosystems and health risk assessment of various RRR models.
Questionnaire for farmer or farm labourer on details of wastewater use in agriculture was developed to elicit details regarding the type of irrigation, type of crops grown using wastewater, mixing of wastewater and ground water, availability of groundwater and advantages and disadvantages of wastewater farming.
Qualitative methods
Observation of usage of wastewater by the farmers, the mitigation measures employed and handling of produce grown was done by the investigators. The sanitation chain of wastewater reuse in agriculture is described.
Analysis
The observational data were collected using two notebooks by the researcher for keeping field notes. In one notebook, the questions to be asked and their answers were noted, and in other notebooks, new and additional information in relation to the study topic was noted down. Observations consisted of comments by farmers, maps, diagrams, and interview notes. Farmers’ exact quotes were written down as much as possible. Their work activities in the field were described without arriving at conclusions. The researchers’ judgments and assumptions were avoided at all costs during observations. Coding of observational notes was done to remove unnecessary information. The sanitation system map was constructed using observational data.
Using the SSP as a guide, exposure group categories, hazards, and hazardous events associated with wastewater use in agriculture were identified. The semiquantitative risk assessment matrix of the SSP was used, and the highest risks associated with wastewater use in agriculture in our study area were identified. For the identified risks, control measures and an incremental improvement plan for the sanitation chain of wastewater were prepared.
RESULTS
The study area was chosen for the presence of the River Dakshina Pinakini, which contains treated, untreated, and partially treated wastewater, industrial effluents, and stormwater drainage. The area has exacerbating factors for sanitation problems such as soil-transmitted helminths and vulnerable population such as farm laborers who are exposed to wastewater. The area has no or intermittent water source for irrigation due to inadequate groundwater supplies, which therefore requires water supply for irrigation from the potentially unsafe water source, which is the River Dakshina Pinakini.
The processes involved in the sanitation chain of wastewater use in agriculture are the components of wastewater such as treated sewage, untreated sewage, treated industrial effluents, untreated industrial effluents, domestic wastewater (gray water), river water, stormwater runoff, solid waste, rainwater, free flow water channels, and agricultural runoffs. The treated, untreated, and partially treated wastewater industrial effluents and domestic wastewater from the metropolitan city of Bengaluru form the major constituent of the wastewater. The disposal of wastewater includes the following modes of transport: direct application on the fields, water sucked into pumps for application, and use of pipes to irrigate the fields. Some farmers who have the availability of groundwater mix groundwater with wastewater for irrigation, and some of the wastewater runs off into drains. The produce grown using the wastewater is sold in local and city markets. The common treatment method of wastewater used in the fields is retention ponds, which reduce the hazards of the wastewater. Wastewater is used for agriculture by direct application, using electric pumps, pipes, mixing with fresh water, and as runoff. The main composition of the wastewater includes liquid wastes such as treated sewage, urine, domestic wastewater, stormwater, industrial treated and untreated wastewater, and solid wastes such as fecal sludge, agricultural waste, slaughterhouse waste, gardening, and industrial waste. Accidentally mixed components such as sharps and solid wastes such as plastic, paper, and electronic waste were not observed during the on-site examination of the wastewater and in interviews with farmers. The methods of disposal of wastewater identified in our study include utilization for the irrigation of crops, washing of cattle and vehicles, and increasing groundwater levels. In effect, Dakshina Pinakini currently serves as a “combined sewer,” in that it carries both sanitary sewage and stormwater runoff. Hence, the water could not even be consumed by cattle in the study area. In interviews with farmers, we conclude that the quantum of wastewater in river would be high during rain. In addition, the color and physical appearance would be different during rain. The water would be relatively dark during dry seasons. This may be due to the dilution factors not playing a role in dry seasons. Farmers also relate to these flow rates in terms of water being powerful and not powerful by the physical appearance of the water. Invariably, the water in dry seasons was black and strong as compared to light colored and not that strong or less acidic during rain.
In the sanitation chain of wastewater use for agriculture, in our study, we identified specific exposure group categories that are described in Table 1.
Table 1.
Exposure group categories for wastewater use for agriculture
| Exposure group category | Description |
|---|---|
| Farmers and farm laborers | Persons who use the wastewater for irrigation of farmlands and other agricultural activities |
| Cattle herders | Cattle taken to wastewater for washing can make the herders get exposed to wastewater |
| Local community | Any person who is living near or downstream from the river Dakshina Pinakini may be passively affected |
| Consumers | Anyone who consumes or uses the products produced using wastewater |
The easy, inexpensive, and perennial availability of wastewater, its abundance, and its capacity to reduce the need for fertilizers were cited by farmers as the reasons for the use of wastewater for agriculture. The disadvantages of the use of wastewater, according to the interviewed farmers, were as follows: It was strong (it could kill the crops due to pollutants present in it), yield could be reduced, there is limited crop choice (not all crops can be grown using wastewater-only finger millet and rice grows well), eutrophication (excess growth of weeds) resulting in blockage of irrigation pipes, foul smell from the water, presence of contact dermatitis, and cracked feet among users.
It was observed that the following crops are grown using wastewater for irrigation:
Cereals and millets: rice, finger millet, baby corn, and sweet corn.
Vegetables: tomato, beans, beetroot, cabbage, cauliflower, cucumber, lemon, broad beans, capsicum, and kohlrabi.
Roots and tubers: beetroot and radish.
Green leafy vegetables: spinach, cilantro, dill leaves, and amaranthus.
Cash crops: mulberry, sugarcane, chilies, eucalyptus trees, banana, and coconut.
Floriculture: blue daisy, marigold, zinnia, and lawn grass.
Fodder: guinea grass and baby corn.
The exposure and transmission routes of various hazards involved in the process of wastewater for use in agriculture are described in Table 2.
Table 2.
Exposure and transmission routes of hazards
| Hazards | Hazardous events |
|---|---|
| Pathogens in the wastewater | Exposure to untreated wastewater while farming or eating |
| Heavy metals | Exposure to untreated wastewater while farming or eating |
| Other pollutants | Exposure to untreated wastewater while farming or eating |
| Malodor | Exposure to untreated sewage during farming |
| Irritation to skin | Exposure of wastewater to the skin during irrigation |
Applying the semiquantitative risk assessment matrix [Table 3], the event of direct ingestion of wastewater by the farming community and ingestion of wastewater after contact with it are the highest risks for farmers in our study.
Table 3.
Semiquantitative risk assessment matrix
| Hazardous event | Likelihood | Severity | Risk score |
|---|---|---|---|
| Direct contact with wastewater while farming | Likely (4) | Minor (2) | 8 (medium risk) |
| Inhalation of aerosols | Likely (4) | Minor (2) | 8 (medium risk) |
| Direct ingestion of wastewater by the farming community | Likely (4) | Major (8) | 32 (high risk) |
| Ingestion after contact with wastewater | Likely (4) | Major (8) | 32 (high risk) |
| Consumption of contaminated produce | Unlikely (2) | Moderate (4) | 8 (medium risk) |
| Vector breeding in wastewater site | Likely (4) | Insignificant (1) | 4 (low risk) |
The control measures for the risks involved in wastewater use for agriculture are described in Table 4.
Table 4.
Control measures for the risks involved in wastewater use for agriculture
| Types of control measures | Details of control measures |
|---|---|
| Treatment | Treatment measure for wastewater before application on field includes setting up of settling tanks or trenches with rudimentary masonry work for impounding water. This enables enhancing physical quality of water (settling of solids). This functions as a physical measure of treatment of wastewater in fields. This is recommended for the study area as per our study observations |
| The WHO Water Safety Plan (WSP) Manual 2009 recommends a detention time of about 22 days in a waste stabilization pond system for unrestricted irrigation or 11 days retention in a WSP system or equivalent for restricted irrigation. | |
| Non-treatment control measures followed | Crop selection and restricted irrigation (i.e., irrigation of all crops, except vegetables and salad crops eaten uncooked). |
| Wastewater application method | Irrigation type: furrow and drip irrigation are followed in the study area. Ridge and furrow irrigation reduces risks associated with wastewater to some extent but the best irrigation option from a health point of view is to allow water to drip from pipes laid along the ground. Drip irrigation requires minimal human contact with wastewater. The flipside to this is that if pre-treatment of wastewater is not done before irrigation, solid wastes might block the irrigation systems. |
| Withholding times: Irrigation is avoided by farmers when pollutants are high in wastewater as indicated by excess forth or malodour | |
| Mixing of wastewater with fresh water: Certain farmers mixed wastewater with fresh water to reduce the pollutants (“power” as termed by the farmers). This facilitates dilution of the purported wastewater and reduces the hazards the farmers is exposed to during wastewater farming. | |
| Non-technical | Washing of hands and feet after work with water and irregularly with soap and water. Farmers and farm labourers were not using PPEs such as rubber gloves, waterproof shoes and mask while practising wastewater farming. Farmers were not practising any specific vector control / contact method either. However, there was a practice of regular health check-ups (positive health seeking behaviour). |
| Local cooking practices involve washing vegetables adequately before cooking and peeling of skin. Most of local cuisine involves use of cooked vegetables and not raw vegetables. |
The improvement plan options [Table 5] were identified, and priority scores were calculated. Of the options, storage of irrigation water before application to fields, provision of a time interval between final irrigation and consumption of produce, washing of produce with freshwater before transporting to market, and hygienic cooking practices obtained high scores in the priority scores.
Table 5.
Improvement plan options for wastewater use in agriculture
| Options | Potential | Technical effectiveness | Acceptability | Priority score |
|---|---|---|---|---|
| Controlling of contamination of river water by improved industrial practices to improve the quality of effluents | 3 | 3 | 1 | 20.25 |
| Controlling the discharge of domestic wastewater and pathogens into the river | 3 | 3 | 1 | 20.5 |
| Controlling direct discharge of excreta into the river by on-site sanitation systems | 3 | 3 | 1 | 20.5 |
| Efficient wastewater treatment plants in upstream | 3 | 3 | 1 | 20.5 |
| Storage of irrigation water before application | 3 | 3 | 3 | 60.75 |
| Targeted education of farmers on improved use of wastewater, PPE, and handwashing practices | 2 | 2 | 2 | 18 |
| Targeted education on the safe handling of crops | 2 | 2 | 2 | 18 |
| Education programs to ensure consistent hygiene practice in food preparation | 2 | 2 | 2 | 18 |
| Targeted education of the community on the prevention of children from playing in wastewater-irrigated fields | 2 | 2 | 2 | 18 |
| Wearing shoes or boots and gloves to prevent contact with wastewater | 3 | 2 | 1 | 13.5 |
| Use of personal protective equipment such as gloves, mask, and boots to prevent exposure to wastewater | 3 | 2 | 1 | 13.5 |
| Improved handwashing and personal hygiene practices among farmers | 3 | 2 | 1 | 13.5 |
| Drip irrigation method | 3 | 2 | 1 | 13.5 |
| Pathogen die off before consumption (provision of interval between final irrigation and consumption) | 3 | 3 | 2 | 40.5 |
| Washing of produce with freshwater before transporting to market | 3 | 3 | 2 | 40.5 |
| Regular deworming of exposed groups and school children in the community | 2 | 2 | 3 | 27 |
| Hygienic cooking practices | 3 | 3 | 3 | 60.75 |
DISCUSSION
In India, most untreated wastewater is let out into water bodies such as rivers.[7] In our study area, the River Dakshina Pinakini is perennial and carries the wastewater of Bangalore City.
Food crops grown using treated wastewater are expected to be as safe as drinking water. When discharge of untreated sewage into rivers is allowed, which in turn is used for farming and consumption of raw produce is possible by consumers, safety of such produce is questionable.[8] However, in our study area, the wastewater used for agriculture has a mixture of treated, partially treated, and untreated wastewater. Farmers also reported that the water was not suitable even for cattle to drink. Hussain et al.[9] observed that wastewater use in agriculture improves the standard of living and creates employment opportunities among farmers in peri-urban areas. This is reflected in our study. Even though our study area is a peri-urban area, and farming is a less profitable occupation as compared to others, many farmers still practice farming due to the easy, less expensive, and perennial availability of water.
In our study, farmers were informed that sometimes the high pollutant content in the wastewater destroys crops. This could be due to possible changes in biomass and microbiota of soil.[10] The presence of organic and inorganic pollutants in the wastewater increases the biochemical oxygen demand, and high amounts of nitrogen and phosphorus can increase the sodicity of soil affecting the soil and crops.[11]
In our study, we identified farmers and farm laborers, cattle herders, local community, and consumers as risk groups for exposure. Common occupational problems among farmers using wastewater for agriculture are skin infections, dermatitis, and fungal infections. Children living near wastewater communities are prone to helminthiasis.[12]
The hazards identified in our study for wastewater farming were pathogens, heavy metals, other pollutants, malodor, and skin irritation. According to the WHO guidelines, a total pathogen reduction of 6 log units for leaf crop consumption and 7 log units for root crop consumption is required.[8] However, in our study area none of these guidelines are being followed. Heavy metals, detergents, and industrial pollutants in wastewater and the nature of farming work, which involves constant exposure to wetness and exposure to fertilizers, could have made the farmers more prone to skin irritation.[13] Hydrogen sulfide and ammonia are common causes of malodor in wastewater. This can cause a nuisance among the farmers and the local community.
Among the risks, the highest risks according to the semiquantitative risk assessment matrix are direct ingestion of wastewater by the farming community and ingestion after contact with wastewater. The farming community does not use any personal protective equipment; hence, there is a high chance of accidental ingestion. Enteric viruses, fecal coliforms, bacterial pathogens, and antibiotic resistance genes in wastewater can result in diarrheal diseases and helminth infections.[14]
To reduce the risks associated with the unrestricted use of wastewater for irrigation, it is recommended that farmers practice the detention of water for 22 days. However, this is not followed by farmers. This could be due to a lack of knowledge and feasibility issues. The provision of interval between final irrigation and consumption is also not practiced due to a lack of knowledge and feasibility issues. The washing of produce is done regularly before selling it in markets. Washing improves the appearance of the produce and increases the value of the produce in the market. The raw vegetables consumed in the study area are usually carrots, tomatoes, and cucumbers. As a practice, these vegetables are usually washed well and consumed. Cucumbers and carrots are usually washed and peeled before consumption.
The study results were disseminated to the farming community by conducting a farmers workshop at the study area. Renowned soil scientist Dr. Ramakrishna Parama and members of the Panchayati Raj Institute were invited as guest speakers and the authors shared the study findings with the farming community. It was an opportunity for farmers to share their woes, the Panchayati Raj Institute to take action, the researchers to enlighten the community regarding safe use of wastewater for agriculture and the soil scientist to add valuable inputs.
In conclusion, on the application of the SSP in the sanitation chain of untreated wastewater in agriculture in the study area, it is observed that simple feasible control measures such as retention of wastewater for 22 days before use in irrigation, the provision of interval between final irrigation and consumption, washing of produce before selling, and hygienic cooking practices can mitigate the risks associated with wastewater farming.
Financial support and sponsorship
This study was supported by the Consortium for DEWATS Dissemination Society- Bremen Overseas Research and Development Association.
Conflicts of interest
There are no conflicts of interest.
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