Use of wastewater for the purpose of producing seedlings of forest species

ABSTRACT

Water has become one of the biggest global concerns, given a possible global supply crisis. Given the scarcity of water, especially in semi-arid regions, and the constant advance of desertification, the use of wastewater has been a viable alternative in the production of seedlings of forest species, mainly for the recovery of degraded areas. Work carried out with species from the caatinga, Eucalyptus grandis, flamboyant and Copaifera langsdorfii. Def. (copaíba) show excellent results in germination and development of forest seedlings, which is caused by the concentration of nutrients from residues.

Keywords: Water, Seedlings, Waste.

ABSTRACT: Water is becoming a major concern worldwide, given a possible supply crisis in the world. Given the scarcity of water especially in semiarid regions and the constant advance of desertification, the use of wastewater has been a viable alternative in the production of seedlings of forest species mainly for the recovery of degraded areas. Work with caatinga species, Eucalyptus grandis, flamboyant and Copaifera langsdorfii. Def. (copaiba) show excellent results of germination and seedling which is caused by the concentration of nutrients from the waste.

Key words: Water, Seedlings, Waste.

INTRODUCTION

Water has become one of the biggest global concerns, given a possible global supply crisis (POSTEL et al., 1996). Gasi (1988) stated that there are different alternatives for the recovery or treatment of wastewater of domestic, industrial or agricultural origins, many of them complex and expensive and others simple and low cost.

According to Tundisi (1999), surface and underground water resources, worldwide, are rapidly lost due to different activities that are intensively developed in river basins, altering both the quantity and quality of water. Observing the topic, Ayres & Westcot (1991) say that the reduction in the availability of good quality water resources and the increase in the production of domestic and industrial waste has driven the use of lower quality water in irrigation, whose evaluation is necessary.

Many countries located in arid and semi-arid regions have included water reuse in water resources planning, given that the scarcity of good quality water has limited urban, industrial and agricultural development. In this sense, effluents are forming an integral part of the national water resources plan in several countries (TANJI, 1997; BOUWER, 2000). In some cases, such as Jordan and Saudi Arabia, there has been a national policy to reuse all effluents generated (PESCOD, 1992). In certain regions of Mexico and the desert coast of Peru, as a consequence of the imbalance of water resources, added to the accelerated growth of cities, agricultural activities were seriously affected, making the use of wastewater mandatory and urgent as the only alternative for survival, making it viable the irrigation of more than 400.000 ha (LÉON & CAVALLINI, 1996).

According to VAN DER HOEK et al. (2002), the greatest advantages of using wastewater for agricultural purposes lie in the conservation of available water and the possibility of supplying and recycling nutrients (reducing the need for chemical fertilizers), contributing to the preservation of the environment. In Brazil, records of the use of wastewater for agricultural purposes are scarce, except in the production of sugar cane, which does not mean that this practice does not occur (BASTOS, 2003), mainly on the outskirts of large cities, where there are Generally, vegetables and forage crops are cultivated for animal feed (KONIG et al., 1998). The use in vegetable crops is questionable because they are food crops.

The reuse of wastewater has been mainly aimed at agricultural and psychological activities; on the other hand, reforestation has only been considered as windbreaks or as perimental cordons to avoid unpleasant odors and improve the aesthetics of sewage treatment plants and areas of use (MARENCO, 1994).

In addition to being a viable alternative to increasing water availability, the reuse of effluents, especially those of urban origin, is an effective way of controlling pollution and preserving the environment, the benefits of which are associated with economic, environmental and public health aspects ( Inhoff & Klaus, 1998). Mancuso and Santos (2003) also indicate that the use of wastewater in agriculture contributes a large amount of nutrients to the soil, increasing crop yields.

According to Cromer (1980), the reuse of effluents in forestry activities, due to its peculiarities, presents itself as a promising alternative, mainly because it does not involve the production of food for human consumption or health risks. Studies carried out in other countries have demonstrated the efficiency of using wastewater in the fertigation of agricultural crops, obtaining excellent results, since they are generally rich in nutrients (BASTOS, 1999).

Wastewater is a term used to characterize waste from different types of water use and origin, such as domestic, commercial and industrial use; those of public establishments, agricultural areas; surface, infiltration, rainwater and other sanitary effluents (VAN HAANDEL & LETTINGA, 1994; JORDÃO & PESSOA, 1995; BRAGA et al., 2002).

For Von Sperling (1996), wastewater is water polluted by the addition of substances or forms of energy that, directly or indirectly, alter the nature of the water body in such a way that it harms the legitimate uses made of it.

Wastewater is classified according to its origin, and can be:

• Domestic – are those that were used for hygienic purposes from buildings inhabited by human beings, as well as public and commercial buildings;

• Industrial - water from small factories, industries and large industrial centers;

• Agricultural areas - are the water resulting from irrigation carried out in large agricultural areas;

• Rainwater – water resulting from surface runoff;

• Infiltration and additional flows – these are water coming from the volume of water that infiltrates underground, and from rainwater that is discharged from various sources, such as gutters, drains and collectors.

Domestic wastewater is generally perennial, and its composition is essentially organic and relatively constant when there is household water control (MENDONÇA, 1990).

MATERIAL AND METHOD:

Observing the topic, Ayres & Westcot (1991) say that the reduction in the availability of good quality water resources and the increase in the production of domestic and industrial waste has driven the use of lower quality water in irrigation, whose evaluation is necessary. Strauss & Blumenthal (1998), referring to this alternative to irrigation, report that wastewater, in addition to allowing the potential use of water and nutrients from sewage for plant growth, also constitutes a method of polishing of treatment plant effluents, but the use of water contaminated by sewage in agriculture must be conditioned on their treatment, restrictions on the type of crop, the choice of application methods and control of worker exposure.

In addition to being a viable alternative to increasing water availability, the reuse of effluents, especially those of urban origin, is an effective way of controlling pollution and preserving the environment, the benefits of which are associated with economic, environmental and public health aspects ( Inhoff & Klaus, 1998). Mancuso and Santos (2003) also indicate that the use of wastewater in agriculture contributes a large amount of nutrients to the soil, increasing crop yields. Therefore, the use of pre-treated wastewater in the production of forest essence seedlings could represent an alternative that allows plants to develop, preserving the environment and obtaining good quality, low-cost seedlings. Therefore, it is necessary to carry out experimental work that can establish a reuse policy on a real scale, which indicates viable conditions, to transform this potential into reality, selecting crops and management practices that maximize the benefit, taking always taking into consideration the reality of man. (Brazil, 1999).

In Brazil, the most common nursery irrigation system is micro-sprinkler, a system that generates large amounts of waste due to factors such as wind, empty spaces and poor distribution of sprinklers in relation to the seedlings. Continuous sub-irrigation is an alternative for saving water, as well as an efficient system for rapid and controlled development of seedlings, and has been used mainly in the management of mini and micro clonal gardens. Aiming to use wastewater, this system is even more favorable, as it reduces the possibility of human and environmental contamination (Augusto et al, 2007).

The main advantages of using treated wastewater in agriculture are:

• Conservation of water resources by replacing top quality water, used in irrigation, with effluents from a sewage treatment plant.

According to the Brazilian Association of Sanitary and Environmental Engineering, in the northeast region of Brazil, around 56% of the population did not have access to water supply services (ABES, 1998). Therefore, replacing part of the water allocated to irrigation with treated wastewater could mitigate this problem, especially since irrigated agriculture is the human activity that demands the greatest amount of water.

• Continuity in agricultural production in locations that have no other source of water during the dry season other than sewage;

Although irrigated agriculture represents only 13% of the world's available arable land, the value of the crops produced on these lands is equivalent to 34% of the total. This potential is most significant in semi-arid and arid regions, such as the Middle East, where irrigated areas comprise only 30% of cultivated areas but contribute 75% of total agricultural production (Arar, 1991).

• Recycling of nutrients present in sewage and consequent savings in fertilizer costs.

Much research has demonstrated that agricultural production is higher when some form of wastewater is used compared to water supply with the addition of artificial fertilizers (Pescod and Arar, 1988). Marecos do Monte and Sousa (1992) report that savings in artificial fertilizers, when reusing sewage in agriculture, can range from US$230/ha to US$530/ha.

WHO recommendations regarding the reuse of wastewater in agriculture

In 1978, the Department of Public Health of the State of California, USA, published the “Wastewater Reclamation Criteria” standard, which required that effluents from sewage treatment plants that were to be used to irrigate crops to be consumed by human beings contained a number of of fecal coliforms less than 2,2 cfu/100mL. In the case of pastures for dairy animals, the wastewater used should not contain more than 23 fecal coliforms per 100mL. (State of California, 1978).

However, subsequent studies on the evidence of disease transmission through the use of wastewater in agriculture (Shuval et al., 1986) showed that the microbiological standards adopted in the State of California were stricter than necessary to avoid risks to health. public health, causing unnecessary expenses in sewage treatment. Based on such epidemiological studies, in 1989 the WHO published the recommendations “Health Guidelines for the Use of Wastewater in Agriculture and Aquaculture” in which the microbiological standards shown in Table 1 were suggested (WHO, 1989).

It is worth noting that of the two standards suggested by the WHO for unrestricted irrigation, less than 1 intestinal nematode egg per liter and less than 1000 fecal coliforms per 100mL, the second is more rigorous, with the absence of intestinal nematodes being common when the number of fecal coliforms is 1000 cfu/100mL (Athayde Júnior, 1999).

Many countries located in arid and semi-arid regions have included water reuse in water resources planning, given that the scarcity of good quality water has limited urban, industrial and agricultural development. In this sense, effluents are forming an integral part of the national water resources plan in several countries (TANJI, 1997; BOUWER, 2000). In some cases, such as Jordan and Saudi Arabia, there has been a national policy to reuse all effluents generated (PESCOD, 1992). In certain regions of Mexico and the desert coast of Peru, as a consequence of the imbalance of water resources, added to the accelerated growth of cities, agricultural activities were seriously affected, making the use of wastewater mandatory and urgent as the only alternative for survival, making it viable the irrigation of more than 400.000 ha (LÉON & CAVALLINI, 1996).

According to VAN DER HOEK et al. (2002), the greatest advantages of using wastewater for agricultural purposes lie in the conservation of available water and the possibility of supplying and recycling nutrients (reducing the need for chemical fertilizers), contributing to the preservation of the environment.

In Brazil, records of the use of wastewater for agricultural purposes are scarce, except in the production of sugar cane, which does not mean that this practice does not occur (BASTOS, 2003), mainly on the outskirts of large cities, where there are Generally, vegetables and forage crops are cultivated for animal feed (KONIG et al., 1998).

The use in vegetable crops is questionable because they are food crops.

RESULTS AND DISCUSSION:

Studies on soil-plant-water management for the production of forest essence seedlings, with the aim of obtaining seedlings of high technical quality and better adaptation to the conditions of the Northeast region, are practically non-existent, which has limited the increase in production and the quality of such seedlings (LUCENA and SILVA, 2000).

The growing scarcity of water resources has limited forestry enterprises (reforestation of degraded areas and urban afforestation) as well as the production of forestry products, causing concern on the part of farmers, nurseries and cooperatives in rationalizing forestry production. As a result, there has been interest on the part of foresters in appropriate techniques and management in order to rationalize the use of water resources.

The use of wastewater in crop irrigation has offered excellent results, since these waters are rich in nutrients (BASTOS, 1999). The use of pre-treated water in the production of forest essence seedlings contributes to ecological agriculture, preserving the environment and, above all, allowing the obtaining of good quality, low-cost seedlings. On the other hand, these seedlings must be produced in substrates whose physical properties are not limiting, receiving water and nutrients in adequate quantities. According to Minami (2000) and Lima et al. (2001), the substrates used in plant multiplication must be easily available for acquisition and transportation, absence of pathogens, have adequate physical and chemical properties, in addition to the support capacity of the plant for which the substrate is intended.

The need to implement a program to restore vegetation cover in areas affected by desertification in Brazil, especially in areas dominated by the Caatinga Biome, leads to an increase in water consumption for the production of forest seedlings. As there is a situation of water scarcity in the Brazilian semi-arid region, where human consumption takes priority over all demands, a problem is created whose cause leads to a constant worsening of the effects of environmental degradation. Therefore, water reuse was sought as a viable alternative to solve, at its origin, the problem of recovering degraded areas through the restoration of forest ecosystems with the use of treated sewage effluent for the production of seedlings.

Augusto et al. (2003) obtained satisfactory results studying the production of Croton floribundus Spreng seedlings. (Capixingui) and Copaifera langsdorfii. Def. (copaíba) in a sub-irrigation system with wastewater resulting from biological sewage treatment. Although the seedlings produced with this wastewater showed lower growth than those produced with mineral fertilizers, no mortality, deficiency or apparent toxicity were observed (Augusto et al, 2007).

Augusto et al (2007), working with the production of Eucalyptus grandis seedlings using wastewater in a continuous sub-irrigation system, reached results that indicated that wastewater from biological sewage treatment systems can be used in the fertigation of nurseries for the production of Eucalyptus grandis seedlings, as all plants survived, without apparent nutrient deficiency or toxicity. However, there was a lower overall development of seedlings produced with wastewater when compared to those produced with chemical fertilizers, due to the lower availability of macronutrients, showing that these seedlings will require more time in the nursery when compared to those produced with fertilizers. minerals. Lucena et al, in the work entitled “Use of substrates irrigated with supply and waste water in the propagation of flamboyant” obtained the results that the irrigation of substrates with supply and waste water did not interfere with the germination of flamboyant seeds.

Conclusions

The wastewater can be used in the fertigation of nurseries to produce seedlings of the species studied (capixingui, copaiba, aroeira, ipê Roxo, jucá, mororó, mulungu, pereiro, eucalyptus, canafistula) as the plants proved to be healthy, vigorous, with good development, good survival, without apparent nutrient deficiency or toxicity.

The development of the root system was favored in the system with wastewater, which is a desirable characteristic for greater survival of seedlings in the field.

The development of seedlings is slower, which leads us to believe that forest seedlings produced using wastewater will require more time in the nursery, when compared to those produced with mineral fertilizers.

Epitácio de Alcântara Freire1

,

Maria Alexandra Estrela1

,

Vera Lúcia Antunes de Lima2.

1Students of the Postgraduate Program in Agricultural Engineering/ Federal University of Campina Grande (

)

2Adjunct Professor of the Postgraduate Program in Agricultural Engineering/ Federal University of Campina Grande (

)

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