ANTECEDENTES MADRE

Generally, treated and untreated wastewaters are widely used for irrigation purposes due to the availability of nutrients and essential elements necessary for plant growth (FAO, 2003). Using wastewater in irrigation will lead to increase the potential yield of most crops reducing the required amount of chemical fertiliser and saving the farmers net cost. However, applying nutrients and elements via irrigation with wastewater to plants which exceeds their requirements, mainly total nitrogen, may lead to excessive vegetative growth and delay in ripening and maturity of the yields, or in some other extreme conditions may lead to the loss of the yield.

Several studies have been undertaken by agronomists trying to quantify the impact of irrigation with wastewater on parameters linked to yield and quality. Agronomists concluded that using treated wastewater in irrigation of plants will increase their potential yield and quality more than what would be otherwise possible. An overview of some of these studies is shown in Table 2.20. In spite of several issues associated with the use of wastewater in irrigation, it still very attractive for use by farmers as it will save fertiliser costs even if in some cases it will not improve the amount and quality of the yield. Excessive nitrogen, phosphorous and potassium available in the wastewater which may exceed the needs of plants will impact negatively on the yield. For example, urea effluent from treatment plants will be a rich liquid fertiliser but if it is highly concentrated then it will impact adversely on corn and rice yields as reported by Singh and Mishra (1987).

Moreover, chemical pollutants available in the wastewater, mainly industrial wastewater, should be taken into consideration when irrigating plants as they will accumulate in plant tissue and then enter the food chain by human consumption. For example, Kalavrouziotis, Robolas, Koukoulakis, and Papadopoulos (2008) conducted

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an experiment in a greenhouse, to study the effect of treated municipal wastewater (TMWW), compared to ordinary irrigation water, on the macro- and micro-elements and heavy metal content of Brassica oleracea var. Italica (broccoli), and B. oleracea var. Gemmifera (Brussels sprouts) plants, as well as on the physical and chemical properties of the clay loam soil, and its inorganic composition, to examine the possibility of TMWW reuse for irrigation of the above vegetables. The results showed that applied TMWW increased significantly, in comparison to control, the content of some macro- and micro-elements in the soil. Furthermore, the levels of the heavy metals in the edible plant parts were very high causing a high health risk factor, and therefore the TMWW studied, cannot be used for the irrigation of these vegetables.

Moreover, the highly frequent application of wastewater will increase the salinity affecting crops with salt sensitivity. This was confirmed by Zavadil (2009) who studied the effect of irrigation with municipal wastewater on vegetables and crops like lettuce, radish, carrot and potato. Primary treated wastewater and secondary treated wastewater were used in this experiment work, while irrigation with local well water or public water supply was used as a control treatment. The results showed that statistically the primary treated wastewater compared to the secondary treated one, significantly increased the yield of all vegetables and crops. However, irrigation with secondary treated wastewater caused an increase in sodium content in radishes and carrots, while irrigation with the primary treated wastewater led to an increase in the sodium content in the edible parts of all vegetables. Moreover, the results showed that irrigation with this water caused a high bacterial contamination in all vegetables.

Also, the high microbiologically contaminated wastewater causes a reduction in the overall crop yield and quality with high potential for contamination by pathogens and intestinal helminths. However, high yields can be achieved by using pre-treated

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wastewater for irrigation of various crops under controlled environmental conditions (Zavadil, 2009). Identification of the agricultural, industrial and human sources of microbial contamination from pre- to post-harvest operations of Cantaloupes (Cucumis melo var. cantalupensis (Naudin)) grown at ten different farms in southern Texas was undertaken by Materon, Martinez-Garcia, and McDonald (2007). The results indicated that irrigation water contained a wide range of microorganisms that could cause human illnesses and were able to survive on the rind of Cantaloupes before, during and after harvesting.

Moreover, traces of hydrocarbons from diesel spills associated with urban run-off or industrial effluent are a more recent challenge (Scholz, 2010; García-Delgado, Eymar, Contreras, & Segura, 2012) which will affect the irrigated soil and crops. For instance, García-Delgado et al. (2012) undertook a greenhouse study in Spain to assess the effect of treated urban wastewater contaminated with hydrocarbons on soil and pepper quality. They concluded that the wastewater application saved fertiliser (37% nitrogen, 66% phosphorus and 12% potassium) and that the total poly-aromatic hydrocarbons and heavy metals (cadmium, lead and arsenic) within the pepper fruits were low. The highest concentration (lower than the proposed threshold concentration for carcinogenicity) was recorded for phenathrene.

These observations contradicted with those obtained by Khan, Aijun, Zhang, Hu, & Zhu (2008) who carried out a greenhouse experiment of lettuce (Lactuca satuva L.) pot planting to assess the concentrations of polycyclic aromatic hydrocarbons and heavy metals (HMs) accumulated in vegetables grown in wastewater-contaminated soils. The results showed that the plant shoots were highly contaminated with polycyclic aromatic hydrocarbons and heavy metals (cadmium, chromium, nick, and lead) which exceeded the guidance limits set by the State Environmental Protection Administration (SEPA),

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China and the World Health Organization (WHO) indicating the potential health risks associated with cultivation and consumption of leafy vegetables on wastewater- contaminated soils. Moreover, irrigation with wastewater contaminated with hydrocarbons will result in increased populations of microbial communities as reported by Benedek et al. (2013) who studied the impact of long-term total petroleum hydrocarbons (TPH), volatile petroleum hydrocarbons, total alkyl benzenes and polycyclic aromatic hydrocarbons on the structure of bacterial communities of four different contaminated soil samples. They concluded that a very high amount of TPH positively affected the diversity of hydrocarbon-degrading bacteria.

According to the literature, the impact of irrigation with treated wastewater will mainly depend on the degree of treatment and the nature of the crops. Economically, irrigation of crops with good wastewater management and practices will achieve several benefits such as increasing the yields, providing extra irrigation water and saving the cost of chemical fertiliser (FAO, 1994, 2003).

Moreover, many studies have been carried out in California to improve a consistent system for wastewater treatment for producing irrigation water which guarantees production of agricultural crops in association with protection of public health (SDLAC, 1977; Sheikh, Cort, Kirkpatrick, Jaques, & Asano, 1990). A key result of these studies showed that reclaimed wastewater could be successfully used for irrigation of crops, even those which may be consumed uncooked, without opposing environment or health requirements (Sheikh et al., 1990; York, Holden, Sheikh, & Parsons, 2008).

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Table 2.20: Overview of wastewater irrigation impact on crops.

Year and author (s) Objectives Methodology Findings Conclusions Day et al., (1975) Impact of irrigation with treated

domestic wastewater on growth and yield parameters of wheat

 Well water mixed with normal dosage of NPK vs  well water mixed with

simulated NPK dose vs  treated wastewater with

no fertiliser

Irrigation with wastewater resulted in:

 High wheat yield

 High wheat protein content  No change in wheat feed

quality in terms of fibre content

Treated wastewater is a high potential source for irrigation that saves fertiliser cost with high yield production

Mortvedt and Giordano,

(1975) Impact of contamination with zinc and chromium tannery wastewater on maize crops

Application of soil highly contaminated with zinc and chromium from domestic wastewater

 High forage production  Zinc available to maize  Low zinc levels with no

change of chromium levels in the maize tops

 Crops uptake chromium with no impact on their growth

Possibility of irrigation with tannery wastewater under good management

Sidle et al., (1976) Accumulation of heavy metals in reed grass and maize over time

Long-time of 11 years irrigation

with wastewater  High chromium and zinc levels in reed grass compared to maize  High metals accumulation

in irrigated soil

 Levels of heavy metals in plants did not pose risk in food chain

 Heavy metals were removed via plant uptake

High level of metals in grass may affect sheep feed and animal programme as well as loading and removal of metals modelling to assess the life of land disposal system

129 Table 2.20 (cont.)

Day and Tuker (1977) Impact of irrigation with treated domestic wastewater on growth and yield parameters of sorghum

 Well water mixed with normal dosage of NPK vs  well water mixed with

simulated NPK dose vs  treated wastewater with no

fertiliser

Irrigation with wastewater resulted in:

 More forage production with high maturity period and low density of crops  Higher sorghum yields  No differences in protein

content with less amino acid

 Increasing in sorghum yields compared to the control

Treated wastewater is a high potential source for irrigation that saves fertiliser cost with high yield production

Bole and Bell (1978) Optimise the utilisation of domestic wastewater irrigation system used for forage production

 Treatment of domestic wastewater using lagoon  Growth and nutrient

consumption

 Efficiency of alfalfa, reed grass, brome grass, wild rye, and wheat grass

 High alfalfa production compared to other grass specious

 Doubling nitrogen production of alfalfa  Excess nitrogen uptake to

be more than that supplied for all except wheat grass  Wastewater supplying

phosphorous exceeding plant uptake

 Alfalfa is the most suitable crop as it has its own nitrogen supplying system (nodules)

 Reed grass can be used for optimal wastewater disposal as it can remove most nutrients and survive flooding

 Wastewater provided forage with sufficient phosphorous but not nitrogen

 System of forage such as alfalfa and reed grass can be considered for optimisation of wastewater utilisation and disposal

130 Table 2.20 (cont.)

Marten et al., (1980) Impact of domestic wastewater on feed quality and yield of maize vs reed grass

Feed quality, dry weight, digestible dry matter of maize vs reed grass were the experiment parameters using two levels of treatment for wastewater for irrigation

 Reed grass less digestible than maize

 Maize produced dry and digestible dry matter more than reed grass

 Higher protein content in reed grass with low digestible dry matter

 Perennial grass showed better efficiency of wastewater nitrogen removal compared to the maize

 High renovation efficiency of wastewater effluent can be achieved with good management of reed grass and maize system Ajmal and Khan (1985) Textile factory effluent impact

on chemistry of soil and growth of two vegetables: kidney beans and lady’s fingers

 Textile effluent diluted to 25, 50, 75 and 100 v/v

 Usual irrigation water for control

 Impact on kidney beans and lady’s fingers

 High BOD, COD, Cl, SO4, K, Ca, Mg with high alkalinity  Dilution wastewater

result to increase elements levels in soil of top more than in subsoil  Na levels in plants

increased

 Dilution of wastewater to 75 and 100 % inhabit plant growth, while dilution of 50 % enhance growing of plants

 Dilution of textile factory effluent can be used for irrigation without affecting soil properties

 Textile effluent is valuable source for irrigation due to nutrient richness  Design of industrial

131 Table 2.20 (cont.)

Ali (1987) Risk assessment of irrigation with domestic water on food crops such as onion alfalfa and summer squash

 Application of sprinklers with secondary treated wastewater mixed with chlorinated wastewater  Treatments with and

without fertiliser  Vegetable

contamination with faecal coliform counting

 After 24 hr irrigation with sprinklers, no faecal coliforms detected on summer squash

 After 15 day irrigation of onion, no faecal coliforms were detected

 Irrigation with secondary treated wastewater and chlorination can be used with vegetables which are cooked before eating  Vegetables processed

before eating can be irrigated with low level of wastewater treatment

 Guidelines for reuse of wastewater for irrigation in Saudi Arabia

Singh and Mishra (1987) Impact of irrigation with urea plant outflow on soil properties, rice and corn growth, dry matter and pigment content

Untreated effluent was diluted v/v to 2.5, 5, and 50% vs a control of tap water

 The effluent is of high alkaline

 Soil properties are affected negatively when irrigated with effluent of > 10% concentration

 High protein content in rice and corn irrigated with effluent concentration of 2.5 and 5% (nitrogen absorption and utilisation)  Effluent of > 10% affected

negatively on seeds germination, dry matter and pigment content for both rice and corn

 Urea plant effluent can be used as a source of liquid fertiliser

 Diluted urea effluent can be used for irrigation of crops

 Pollution and

eutrophication control is required

132 Table 2.20 (cont.)

Misra and Behera (1991) Impact of irrigation with paper industry effluent on rice growth, carbohydrates and protein content  Untreated effluent of various dilution vs distilled water  Impact of effluent concentration and exposure time on rice seedlings

 Increasing of effluent concentration and exposure time adversely affect rice growth, carbohydrates and protein content

 Protein content is highly affected by effluent concentration and can be considered as bio-indicator for phytotoxicity by the effluent

 Paper industrial outflow is not suitable for irrigation

 Regulation for paper industry pollution is required

 Phytotoxicity and pollution risk should be evaluated  Eutrophication and pollution

control is required

Aziz et al., (1995) Impact of irrigation with crude oil refinery wastewater on growth and yield of four wheat varieties

 Treated effluent vs a control of ground water  Same dose of fertiliser is

used

 Assessing growth parameters of shoot length, leaf, fresh and dry weight,

 Assessing plant yield parameters of grain yield, protein, and carbohydrate contents

 Treated effluent followed the standards so it is suitable for irrigation  Irrigation with treated

effluent did not affect soil properties  Irrigation with treated

outflow results in increasing of plant growth, yield, protein and carbohydrate content  Crops showed better

performance due to additional nutrients available in the treated wastewater

 Response of plants to treated effluent was different from one cultivar to another

 Treated effluent did not affect soil properties and can be used for crop irrigation

 Evaluation of long-term impact is required  Policies for industrial

pollution and food security are required

133 Table 2.20 (cont.)

Aziz et al., (1996) Impact of long-term irrigation with petrochemical refinery wastewater on

 Grain and soil heavy metal accumulation  Yield parameters of six

cereals: wheat, triticale, chickpea, lentil, pigeon pea and summer moong

 Treated effluent vs a control of lake water for 8 years

 Same dose of fertiliser is used

 Impact on soil and yield of crops

 Treated effluent followed the standards so it is suitable for irrigation  No significant

accumulation of metals in soil and grains  Metals levels in grain

were below standards and suitable for human consumption

 Irrigation with

wastewater increases the yield for all crops except moong

 Risk of soil contamination with metals affecting food chain in the future is expected

 Policies for industrial pollution and food security are required

Howe and Wagner (1996) Impact of irrigation with paper mill wastewater with

application of gypsum on soil and cottonwood growth rate and sodium uptake

 Untreated wastewater  Four gypsum application

rates w/w of 100, 175, 325 and 625 mg on wastewater base

 Wastewater pH and rate of gypsum application  Cotton biomass, stem

sodium and leaves calcium, potassium and sodium

 Cottonwood biomass production is affected by gypsum application and not pH

 Stem biomass production is dependent on pH  High cottonwood growth

with application of gypsum at low pH values

 Stem and leaves sodium levels were affected by gypsum application rate and not pH

 Gypsum application and wastewater pH affected infiltration rate

 Problem of sodium accumulation in the irrigated soil, thus

application of gypsum was the management action  Management of calcium

as amendment when irrigation with sodic wastewater is required  Long-term evaluation is

134 Table 2.20 (cont.)

El Hamouri et al., (1996) Impact of irrigation with domestic wastewater on soil and yield microbiological quality, the hygienic quality of salt sensitive crops such as cucumber and turnips as well as salt tolerant crops such as alfalfa, corn, zucchini, beans, and tomato

 Raw wastewater  Wastewater treated by

stabilisation pond  Ground water

 Irrigation with different methods: surface, drip and sprinklers

 Assessing soil and crops faecal coliform and helminth eggs contents

 Wastewater stabilisation pond produced effluent meeting WHO guidelines for irrigation

 Cucumber was highly affected by salinity with lower yield when using raw wastewater compared to that of treated

wastewater

 For salinity tolerant crops there were no significant differences in yield of wastewater and ground water

 No helminth eggs were detected in soil and crops irrigated with treated wastewater, while highly detected in those irrigated with raw wastewater  Raw wastewater was not

suitable for irrigation  High crop performance

and yield was recorded for drip irrigation system

 Using of treated

wastewater for irrigation crops of high salt sensitivity in salt areas will be highly

advantageous in terms of reduced salt impact on crop yield and growth, reduced aquifer

salinisation with saving of fertiliser cost

 Technology for wastewater treatment is required

 Policy development for arid and saline areas is required

135 Table 2.20 (cont.)

Shahalam et al., (1998) Impact of irrigation with wastewater on soil and crops such as alfalfa, tomato and radish and risk to health and of ground water pollution

 Treated wastewater vs standard fresh water with and without fertiliser  Impact on growth and

yield of crops

 Impact on soil porosity, pH, salinity, alkalinity and drainage

 Levels of faecal coliform on irrigated crops and environments

 Trends of yield: Alfalfa: fresh water with fertiliser > wastewater with fertiliser, Radish: no significant differences when using

wastewater, Tomato:

wastewater only > wastewater with fertiliser

 Irrigation with wastewater mixed with fertiliser was comparable with fresh water mixed with fertiliser  Increasing soil porosity

and salinity with lowering pH when irrigating with wastewater

 No contamination was detected through subsurface drainage analysis

 No faecal coliforms were detected on tomatoes after 24 hr with no odour or synthetic impact in terms of hygienic quality

 Irrigation with wastewater below the standards did not show any risk to human, soil or environment, however, chlorination is required

 Using wastewater for irrigation in Jordan is a valuable solution for the water scarcity problem in such regions

 Policy for national water security is highly required

136 Table 2.20 (cont.)

Parames-waran (1999 Irrigation with urban wastewater agro-economic feasibility for Jerusalem artichoke in Australia

 Irrigation using furrow method

 Several artichoke cultivars were used

 Plant biomass (top and tuber yield) and nutrient analysis

 Soil salinity and pH  Impact of long-term

irrigation with wastewater

 Artichoke requires a lot of fertiliser supplied by wastewater  No deficiency in nutrients were detected  No symptoms of growth toxicity or damage in growth due to high level of nutrients in the wastewater  Nutrients levels were

higher in the top than tuber parts

 High yield of artichoke irrigated with wastewater

In document Eficacia de una breve intervención temprana basada en la evaluación del desarrollo del neonato prematuro: efecto sobre el estrés, la depresión y las percepciones maternas (página 179-184)