Blanca Jimenez Treatment and Reuse Group Institute of Engineering, UNAM-Mexico GUIDELINES FOR THE SAFE USE OF WASTEWATER, EXCRETA AND GREYWATER Volume 2 Wastewater use in agriculture

70 % of the world water extracted is used for agriculture 75% of the irrigated area is located in developing countries There is a high dependence on irrigation for food production (United Nations 2003) Agriculture Freshwater Withdrawal in 2000

Blue water scarcity for 2025

Pumping Sewage on Crops for Fertilizer Source: Harper’s Weekly, 1890, Photo IV.1; from The Search For The Ultimate Sink by Joel A. Tarr, The University of Akron Press, 1996

In 2006, still is a practice but….. Strawberry Farm, Irvine, CA The Mezquital Valley, México At least 20,000,000 ha in 50 countries are irrigated with raw or partially treated wastewater and > 1/10 of the world’s population consumes crops irrigated with wastewater. Worldwide more than 800 million farmers are engaged in urban and peri-urban agriculture (UNDP, 1996).

Background WHO (World Health Organization) (1973), Reuse of Effluent: Methods of Waste-water Treatment and Health Safeguards, Technical Report 517, WHO, Geneva. WHO (1989) Health Guidelines for the Use of Wastewater in Agriculture and Aquaculture. Report of a WHO Scientific Group, Technical Report Series No. 778, WHO, Geneva  Need to update the guidelines taking into account recent scientific evidence of effects, include changes in population characteristics, changes in sanitation practices, better methods for evaluating risk, social/equity issues and socio cultural practices WHO (2006) GUIDELINES FOR THE SAFE USE OF WASTEWATER, EXCRETA AND GREYWATER

Objectives To have criteria accepted worldwide  (No more California Title 22 vs WHO) To USEFUL, FLEXIBLE, LOCAL ADAPTED AND IMPLEMENTABLE criteria to be used World wide

Main Characteristics DIFFERENCES It is a methodology to set up standards No guidelines values but health goals Very explicitly recognized advantages of reusing wastewater Considers local capabilities and constraints SIMILARITIES Still proposed a high level of health protection

Structure Assessment of health risk Health based targets Health protection measures Monitoring and system assessment Socio cultural Aspects Environmental Aspects (Positives and Negatives) Economical and financial Considerations Policies aspects Planning and Implementation

The Stockholm Framework Integrated approach that combines risk assessment and risk management to control water related diseases Basis

Health concerns when wastewater is reused to irrigate The risk will only be of public health importance IF it increase the incidence or prevalence of disease i.e., importance or impact is different in each region Group exposed Infections risks Helminths infections Bacterial/ viruses Protozoa ConsumersSignificantIncreased if >10 4 TC/100 mL No direct evidence Farm workers and their families SignificantIncreased if >10 4 TC/100 mL Insignificant Nearby Communities Not studied for sprinklers Significant with flow and furrow irrigation Increased for sprinkler irrigation if > TC/100 mL < TC/100 mL not associated with viral infections No data for sprinkler irrigation

Difference in primary risks Diarrhoeal disease incidence per person per year Region0-4 years5-80+yearsAll ages Developed Developing World Source: WHO, 2006 (adapted from Mather et al., 2002 ) For regions with low sanitation level and poor conditions: Helminthiasis (several kind) For regions with high levels of sanitation and public health: Viruses, but as well some emergent diseases

Definition of a tolerable risk Based on local conditions (Public health level) Priorities (types of diseases and relative importance) Capabilities (institutional, economical, social)

Assessment of Health risks An actual risk exists if (ALL): a)An infective dose of a pathogen reach a crop or a a pathogens that arrive into a crop multiplies on it to reach an infective doses b)The infective doses reach a human host (directly or indirectly through a vector) c)The human host become infected d)The infections doses cause disease or further transmition

Type of agriculture Recommendation for viruses, bacteria and protozoan pathogens Guidelines for Helminth ova Unrestricted≤10 −6 DALY loss pppy≤1/L (arithmetic mean) ) Restricted≤10 −6 DALY loss pppy≤1/L (arithmetic mean) Localized≤10 −6 DALY loss pppy(a) Crops growing in or near the soil : ≤1/L (AM) (b) No recommendation for crops growing above soil and grown with drip irrigation Microbiology METHODOLOGY (QMRA) Epidemiology SEVERAL OPTIONS to control risk

The amount of pathogens that can be ingested without exceeding a tolerable risk  As result, the permissible number of microorganisms per L of wastewater that can be used to irrigate a certain type of crop is obtained Based on  A probabilistic calculation of catching an infection from a single dose (d) of a certain pathogen (P), i.e. evaluating P 1 (d) during several exposures  Done using mathematical models (Exponential dose-response and the Beta-Poisson model) but other models or different constants can be used CONSULT Prof. Mara’s web site stewater%20reuse%204_files/Default.htm Quantitative Microbial Risk Analysis (QMRA )

Element/compound Soil concentration Organic compound Soil concentration (mg kg −1 ) Antimony36Dichlorobenzene15 Arsenic82,4–D0.25 Barium*302DDT1.54 Beryllium*0.2Dieldrin0.17 Boron*1.7Dioxins Cadmium4Heptachlor0.18 Fluorine635Hexachlorobenzene1.40 Lead84Lindane12 Mercury7Methoxychlor4.27 Molybdenum0.6PCBs0.89 Nickel107PAHs (as benzo(a)pyrene)16 Selenium6Pentachlorophenol14 Silver3Phthalate13,733 Thallium*0.3Pyrene Vanadium*47Styrene0.68 Aldrin0.482,4,5–T3.82 Benzene0.14Tetrachloroethane1.25 Chlorodane3Tetrachloroethylene0.54 Chlorobenzene211Toluene12 Chloroform0.47Toxaphene Trichloroethane0.68

To standardized the acceptable risk caused by different agents in different norms (Drinking water a risk of for cancer while in irrigation a risk of for diarrheas) DALY = Disability-adjusted life year 1 Daly = 1 lost year of healthy life and the burden of disease as a measurement of the gap between current health status and an ideal situation where everyone lives into old age free of disease and disability It combines in one measure the time lived with disability and the time lost due to premature mortality. Definition of the tolerable risk

WHO recommendation: ≤ DALYs lost Is extremely safe, as people expect their drinking water to be extremely safe <<< than the actual incidence of diarrhea disease in the World that is of 0.7, i.e, For 1 person is equal to loose 31.5 seconds in a year ¡¡¡¡ But for a community means to loss 1 year per million people

The desired level of protection can be reached through a combination of management control options such as: –Wastewater treatment –Crop restriction –The irrigation method –Food preparation Washing Disinfection Peeling Cooking –Hygienic practices at food market –Vaccines and medication, etc….. Hence –Methodology/criteria defines the total removal/inactivation efficiency needed to be achieve (examples are provided in Vol 2) –How to reach it is a national decision

Pathogen reduction (log units) achieved by health protection control measures Control MeasurePathogen log reduction Notes Wastewater treatment1-6The required pathogen removal in a WWTP depends on the combination of the health protection measures Localized irrigation (low-growing crops) 2Root crops and crops such as lettuce that grow just above, but partially in contact with the soil Localized irrigation (high growing crops) 4Crops, such as tomatoes, the harvested parts of which are not in contact with the soil Spray/sprinkler drift control 1Use of micro-sprinklers, anemometer controlled direction switching sprinklers, inward –throwing sprinklers, etc Spray sprinkler buffer zone 1Protection of residents near spray or sprinkler irrigation. The buffer zone should be at least m Pathogen die-off0.5-2 per day Die-off on crops surfaces that occurs between last irrigation and consumption. The log unit reduction depends on climate (temperature, sunlight intensity, crop type, etc.) Produce washing1Washing salad crops, vegetables and fruit with clean water Produce disinfection2Washing salad crops, vegetables and fruit with a weak disinfectant solution and rinsing with clean water Produce peeling2Fruit and root crops Produce cooking5-6Immersion in boiling water until the food is cooked ensures pathogen destruction

Because normally microorganisms content in wastewater is very high what it is defined is log removal/inactivation Examples options for the reduction of viral, bacterial and protozoan pathogens that achieved a health based target of ≤10-6DALYS pppy Less treatment maybe more economical Less treatment implies more supervision sites Washing = More public involvement Involuntary soil ingestion from farmers Developing countries Developed countries California Title 22 ≤ 2.3 FC/100 ml (virtually Zero) ONLY with treatment Monitoring WWTP at T level

Monitoring Urban areas: 1 sample each two weeks for E. coli and 1 sample per month for Helminth ova Rural areas: 1 sample each 1−6 months for helminth ova For pathogens, instead of measuring an INDICATOR (Thermoloterant coliforms) can be used

Helminth eggs ≤ 1 Helminth egg/L for both restricted and unrestricted irrigations  EXCEPT for drip irrigation+high growing crops (crops not growing down or on the soil), for this case there is NO recommendation When children under 15 are exposed to wastewater in farmer fields additional control measures (antihelminthic chemotherapy) are recommended to be followed IF there are evidence of damages

( b) Data from full scale plants (c) Theoretical efficiency based on the removal mechanisms (d) Data from tests with up to 2 log units initial; removal might be greater than that reported or not (e) Data from Laboratory Tests

Chapter 8 Environmental Aspects Wastewater as an important source of water and nutrients Uses soil capacity to remove pollutants Can cause side effects if not planed Has Negative but also POSITIVE impacts Chapter 9 Economical and financial consideration (for encouraging safe use of wastewater) Chapter 10 Policy Aspects Clear National Policy Appropriate legal framework, Adequate Institutional Framework, Appropriate and implementable regulations, Chapter 9 Planning and Implementation Strategies including elements on communication and interaction with stake holders and the collection and use of data for retrofitting

Summarizing Not fixed values but a Methodology to set up standards Each countries can select the disease caused through agricultural irrigation in their region to control Each country can even vary the level of protection desired based as long as it progressively tends to the goal proposed Flexibility to control risks allows economical costs optimization

End Notes WHO criteria is to protect HEALTH, and had nothing to do to protect soil, groundwater can crop productivity (attention need to be put when wastewater contains important amount of industrial wastewater) Who guidelines recognizes the beneficial reuse of wastewater to increase crop production as long as health is protected The 10-6 DALYs goals is still very protective and may not be unachievable in some countries as first step HO are a key parameter to control, BUT, since the 1989 guidelines the lack of capacity to measure this parameter is evident in several countries