The present study was conducted to assess selected heavy metal levels (Cu, Fe, Zn, Ni and Pb) in soil and plants that are irrigated by mixed industrial and domestic wastewater in the Buffalo City region. Three types of samples were studied: soil, water and vegetables (spinach and beetroot). Soil analysis showed that most of the heavy metals were found to be acceptable within the SEPA limits. Most of the heavy metal concentrations found in the wastewater indicate that the water is not suitable for irrigation or for livestock use, according to guidelines from the Department of Water Affairs and Forestry of South Africa. The level of copper in the wastewater effluent exceeded the level specified by SEPA limits. In the wastewater the lead concentration averaged 3.24 and 1.98 ppm in Tshatshu (TS) and Mlakalaka (ML) respectively, which shows that both sites are not suitable for both irrigation and livestock usage. The heavy metal levels (Ni, Pb, and Cu) in both spinach and beetroot samples exceed the criteria specified by the WHO and SEPA standards. The study recommends terminating the usage of effluent for irrigation and further investigation or monitoring in these water sources.

Orientadores: Edson Eiji Matsura, Regina Celia de Matos Pires / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-22T03:27:28Z (GMT). No. of bitstreams: 1 FlorezTuta_Natalia_M.pdf: 2316515 bytes, checksum: 721b6df4bb1b30704c991a946995725f (MD5) Previous issue date: 2013 / Resumo: A demanda mundial por açúcar e bioenergia cresce nos dias atuais resultando em aumento da produção da cultura da cana-de-açúcar, entretanto, as áreas de cultivo se expandem para regiões onde o recurso hídrico é um fator limitante para a produção. Neste contexto, uma alternativa para promover a produtividade é o uso de outras fontes de água como os efluentes de esgoto tratado, contribuindo com a sustentabilidade no setor. No Brasil o reuso de águas para agricultura é ainda recente, o qual limita o seu uso, considerando a falta de regulamentações para o seu adequado manejo e disposição. Assim os efluentes de esgoto, constituem-se numa problemática ambiental (poluição dos corpos de água), social (risco à saúde), e, econômica, a qual deve ser estudada, com o objetivo de obter informação que contribua à criação de legislações que contribuam à mitigação e ou diminuição dos impactos negativos deste tipo de efluentes no ambiente e na sociedade, assim como a diminuição do gasto anual do país para a despoluição dos recursos hídricos e do solo. Entretanto, são poucas as informações existentes ao que refere à disposição via gotejamento subsuperficial e aos efeitos no desenvolvimento e produtividade da cana-de-açúcar. Diante do exposto, o presente trabalho teve o objetivo de avaliar o efeito da irrigação com efluente de esgoto tratado, aplicado via gotejamento subsuperficial no desenvolvimento vegetativo e produtividade da cana-de-açúcar variedade RB86-7515 no ciclo da cana-planta, na região de Campinas - SP. Foram avaliados os parâmetros agronômicos e tecnológicos das plantas de cana-de-açúcar submetidas à irrigação com duas qualidades de água (efluente de esgoto tratado e água de reservatório superficial), dois níveis de fertirrigação (com e sem) e duas profundidades de instalação da fita gotejadora (0,20 e 0,40 m). A partir dos 303 dias após o plantio foram realizadas as medições dos parâmetros agronômicos, já as analises tecnológicas foram realizadas a partir dos 358 dias após o plantio. Os tratamentos não influenciaram significativamente o desenvolvimento agronômico das plantas, em relação ao tratamento não irrigado. Com relação à produtividade, o maior valor estimado (281 t ha-1) foi alcançado no tratamento (T4) irrigado com efluente de esgoto tratado, fertirrigado e com fita gotejadora instalada a 0,40 m de profundidade, sendo superior ao tratamento não irrigado em 47 t ha-1. No entanto, o tratamento T4 atingiu um valor médio de açúcar total recuperável de 125 kg ha-1, sendo inferior ao tratamento sem irrigação em 10 kg ha-1, e ao tratamento irrigado com água de reservatório superficial, fertirrigado e com fita gotejadora enterrada a 0,20 m, em 35 kg ha-1. A irrigação com efluente de esgoto tratado na profundidade de 0,40 m no estádio de crescimento intenso, não promoveu o aumentos nos valores dos atributos agronômicos e tecnológicos da cana-de-açúcar variedade RB86-7515. O aumento na produtividade média foi de 17% no ciclo da cana-planta comparado com a cultura em sequeiro com adubação convencional, quando aplicada a irrigação com efluente de esgoto tratado junto com a fertilização realizada por gotejamento subsuperficial instalado a 0,40 m / Abstract: The increasing world demand for sugar and bioenergy drives sugarcane production to high standards. Since the plantations grow toward regions of low hydric resources, the application of treated sludge is identified as an alternative for hydric supply, contributing, that way, to the sustainability of the sector. Water reuse in Brazil is a quite recent practice which does not account with regulations to support an adequate application and disposition. Sludge effluents constitute important environmental problems (water bodies pollution), social problems (health risks) as well as economic problems which should be studied to generate laws to contribute to negative impacts mitigation or diminution of these kinds of effluents in the environment and in the society and the country annual expenses to revert soil and water resources pollution. However, only little information associated to drip subsurface application effects on sugar cane crop productivity and development is available. Based on what it has been exposed before, this research work intends to evaluate the treated sludge irrigation as applied by means of subsurface drip irrigation technique on the RB86-7515 sugar cane vegetative and productivity development on the cane plant cycle in the Campinas, São Paulo region. Treated sugar cane plants (with two water qualities, i.e., treated sludge effluent and superficial reservoir water) agronomic and technological parameters have been determined for two distinct dripping tape installation depth (0.20 and 0.40 m). Agronomic parameters have been measured 303 days after the plantation, meanwhile the technological analyses were carried after 358 of the plantation. Treatments did not show significant influence on the agronomic plant development if compared with the non-irrigated treatment. Regarding productivity, T4 treatment (irrigated with treated sludge effluent, fertirrigated and with dripping tape positioned at the depth of 0.4 m) exhibited the highest estimated value (281 t ha-1) surpassing the non irrigated treatment by 47 t ha-1. However, treatment T4 reached an average recoverable total sugar of 125 kg ha-1, which was lower of the non-irrigated treatment by 10 kg ha-1 and also lower of the treatment with superficial reservoir water, fertirrigated and with the dripping tape positioned at 0.20 m by 35 kg ha-1. Irrigation with treated at the depth of 0.4 m at the intense growth level did not promote the increase of the agronomic as well as of the technological sugarcane attributes associated to the RB86-7515 sugarcane variety. The average productivity increase was of 17% on the cane plant cycle as compared with the dry (sequeiro?) crop with conventional fertilization when the treated sludge effluent together with the irrigation the fertilization carried with subsurface dripping positioned at 0.4 m / Mestrado / Agua e Solo / Mestra em Engenharia Agrícola

Scarcity of water for irrigation is a serious hindrance for small-scale farmers in sub-Saharan Africa. The use of good quality water for irrigation has resulted in increasing pressure on such water which has prompted sourcing of wastewater as an alternative. One possibility, being investigated by eThekwini Water and Sanitation (Durban, South Africa), is to install anaerobic baffled reactors within local communities to treat wastewater to allow its use for agriculture. The success of wastewater irrigation depends on the ability of the soil to assimilate the water, nutrients and any other contaminants that are applied to it. The aim of this project was to investigate the potential of an anaerobic baffled reactor (ABR) effluent as both an irrigation and nutrient source for use in peri-urban agriculture. The effluent was slightly alkaline (pH 7.40–7.60) and in class C2S1 (medium-salinity/low sodicity water) according to the United States Soil Salinity Laboratory classification for irrigation waters. It was very low in heavy metals, values being below permissible levels according to the Food and Agricultural Organisation (FAO) of the United Nations and the South African Department of Water Affairs and Forestry (DWAF) guidelines for water use in agriculture. The total solids were low thus particulate matter was minimal with a greater concentration of the major elements found in solution. An investigation was carried out to ascertain the behaviour of the effluent when applied to soil and how the soil was able to adsorb plant nutrients from it. A soil column study was undertaken in the laboratory with three contrasting soil types namely a sandy soil (Longlands, E horizon), an organic soil (Inanda, A horizon) and a clayey soil (Sepane, A horizon). The effluent was leached through the soil while distilled water was concurrently used as a control. Results indicated that after application of 16 pore volumes, leachates from the columns contained concentrations of Na, equal to that in the incoming effluent for all soils. The concentrations of Ca and Mg were lower in the leachates than in the original effluent indicating adsorption in the soils. Phosphorus was the element that was most strongly adsorbed in all soils. While its adsorption in the Ia could be attributed to organic matter and the presence of iron oxides and oxyhydroxides, the clay type and amount in the Sepane was likely to have been responsible for P adsorption. The NO₃-N, which was initially low in the effluent, increased as leaching progressed, while the NH₄-N decreased. In the water-leached columns, elements were leached out of soil because none were added with the water. At the end of leaching, columns were allowed to drain and then sectioned into 2 cm segments. The 0-2 cm, 8-10 cm and 14-16 cm segments representing the top, middle and bottom parts of the column were analysed for inorganic-N, phosphorus and potassium. The elemental content of the 0-2 cm segment was significantly higher (p<0.05) than the lower segments in all columns for soluble P in all soils. This reflects the immobile nature of P in soils and confirmed the high amounts of P retained by the soils. There were significant differences between the effluent and the water-leached soils in terms of P retention. The amount of inorganic-N and K in the top layer was not significantly different from the other layers. In the Ia 0–2 cm segment, a pH increase of about 1.3 pH units was recorded in the effluent-leached columns when compared to the equivalent segment in the water-leached columns. A glasshouse study was undertaken to assess the availability to maize of nutrients from the effluent. Maize was grown for 6 weeks in pots filled with the same soil types used in the columns study except that a similar sandy soil, Cartref (Cf, E horizon), replaced the Lo due to inadequate availability of the latter. Fertilizer (N, P and K) was applied at the full recommended rate, half the recommended rate and zero fertilizer for each of the three soils used. This corresponded to 0, 100, 200 kg N ha⁻¹ for all soils; 0, 40, 80 kg P ha⁻¹ and 0, 50, 100 kg K ha⁻¹ for the Cf; 0, 10, 20 kg P ha⁻¹ and 0, 102.5, 205 kg K ha⁻¹ for Ia; and 0, 30, 60 kg P ha⁻¹ and 0, 5, 10 kg K ha⁻¹ for Se. Lime was applied to the Ia soil at the rate of 10 t ha⁻¹. Plants were watered with either effluent or tap water. Dry matter yield and nutrient concentrations for effluent-irrigated maize were significantly higher (p<0.05) than for all equivalent fertilizer applications in the water-irrigated plants. The unfertilized effluent-irrigated plants were not significantly different from the fertilized water-irrigated plants, but performed as well as the water-irrigated plants at half fertilization irrespective of soil type. Phosphorus deficiency was observed in the Ia and Se soils but not in the Cf soil, irrespective of fertilizer treatment. Plants grown on the Cf soil irrigated with effluent and fully fertilized had the highest above-ground dry matter yield (4.9 g pot⁻¹) and accumulated the most nutrients namely N, P, K, Ca and Mg than all other treatments. After harvest the most marked changes had occurred in the Cf soil for P as the effluent-irrigated soils were significantly higher (p<0.05) than the water-irrigated soils reflecting the P input from the effluent. The effect of effluent on soil and plants was further investigated by planting maize on the Ia soil without lime application. Plants that received effluent irrigation and no lime had significantly higher (p<0.05) dry matter yields and accumulated more N, P and K than the water-irrigated with no lime as well as the equivalent limed treatments. This suggests an interaction effect between the lime and the effluent with its effects obvious on above-ground dry matter yield and plant N, P and Mg. A soil column experiment using the Cf, Ia and Se soils and planted with maize was conducted to assess the ability of plants to take up nutrients with concurrent leaching. Plants from the Cf soil recorded the lowest above-ground dry matter yield which was observed from the less vigorous growth as compared to plants in the Ia and Se soils. This growth pattern could also be explained by the low N accumulation in the plants from the Cf soil. Unlike N, P in plants grown on the Cf soil was significantly higher (p<0.05) than in the plants on the Ia and Se soils, despite having the least P gain from the effluent. The readily available P triggered both more uptake and also greater losses through leaching. The rate at which P was being supplied from the effluent was greater than its uptake by the plants and with limited capacity to hold onto P in this sandy soil there was inevitably loss though leaching. A pot experiment was conducted to investigate the interaction effects between lime and effluent. Lime type (calcium hydroxide or dolomite) was applied to two acidic top soils namely Inanda and Avalon at 0%, 25%, 50%, 75% and 100% of the recommended rates for these soils. Maize was planted and after 6 weeks it was harvested and evaluated for above-ground dry matter yields and plant nutrient concentrations. Non-significant effects were recorded for above-ground dry matter, N, P and K as a result of altering the liming rate and type within each soil. The effects of lime application were apparent in the soils after harvest as increasing the lime rate caused an increase in pH and an inverse relationship with the exchangeable acidity and acid saturation in soils, as expected. Although the unlimed treatments did not impact on the acidity as much as the limed treatments, effluent irrigation was shown to reduce soil acidity after harvest when compared to the soils at the beginning of the experiment. Phosphorus accumulation in plants was also unaffected by either lime rate or type which showed that effluent irrigation could influence P availability and further liming would not accrue benefits to the soil so as to influence plant P uptake. Based on these data, ABR effluent could be perceived as a resource rather than a waste product. It could conveniently be used for irrigation provided there is soil and plant monitoring to assess build-up of elements especially in the long term. Further investigations have to be carried out on other crop types both in the field and glasshouse to ascertain nutrient uptake and effect on different soil types. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

Orientador: João Carlos Cury Saad / Banca: Hélio Grassi Filho / Banca: Sergio Nascimento Duarte / Resumo: A crescente expansão demográfica, o aumento da demanda por água potável, a elevação dos índices de poluição, o manejo inadequado de solos e florestas, e a contaminação de rios e lençóis freáticos têm causado sérios problemas ambientais, indisponibilizando grande porcentagem da água doce existente para utilização direta. Estima-se que apenas metade da população da América Latina seja beneficiada com redes de coleta de esgoto e que 90% deste volume coletado esteja sendo despejado em algum corpo de água superficial sem tratamento prévio. Como alternativa para este problema, grande quantidade de águas residuárias tem sido utilizada na agricultura, tornando imprescindível o desenvolvimento de novas tecnologias e métodos de aplicação segura destes efluentes na irrigação de produtos para consumo humano. Visando a necessidade de desenvolver técnicas seguras de aplicação de águas residuárias na agricultura, buscou-se no presente trabalho comparar parâmetros de produção, qualidade microbiológica e acúmulo de nitrato na cultura da alface americana, submetida à irrigação com água potável e com efluente de tratamento de esgoto doméstico, nos sistemas de irrigação por gotejo (superficial e enterrado), sulcos e microaspersão. A alface foi cultivada a campo, na Fazenda Experimental Lageado, da Faculdade de Ciências Agronômicas, localizada no município de Botucatu. As irrigações foram realizadas a cada 48 horas, durante os últimos trinta dias da cultura, repondo a lâmina evapotranspirada neste período. Verificou-se neste trabalho que os maiores valores de produção foram obtidos na irrigação por gotejo superficial, com águas residuárias. Quando comparada a influência do tipo de água utilizada em cada sistema, os valores de produção obtidos também foram maiores para a irrigação com águas residuárias no gotejo superficial, gotejo enterrado... (Resumo completo, clicar acesso eletrônico abaixo). / Abstract: The demographic expansion, the demand increase by potable water, the increase on pollution rates, the unsuitable soil and forests management, and the contamination of rivers and subsurface water have caused serious environment problems, and it became unavailable a high percentage of water for direct use. Only 49% of Latin American population has a sewer net; from this number, it was estimated that 90% hasn't been treated before being thrown away in a surface water source, causing more problems. A high quantity of wastewater has been used in agriculture as an alternative to this problem, what attracts the attention to the need of more researches about the development of a new technology and secure methods to apply effluents on irrigated crops to human consume. Counting on the possibility of develop secure techniques to apply wastewater in agriculture, this work had the aim of comparing American lettuce production, microbiological quality and nitrate level, using irrigation with potable water and domestic sewer treatment effluent, under drip (surface and subsurface), furrow and sprinklers irrigation systems. Lettuce was planted in a field, on Lageado Experimental Farm, Agronomical Sciences College, São Paulo State University, in Botucatu / SP, Brazil. The irrigations were carried out each 48 hours, during the last thirty days of the crop, adding the water rates lost in this period. It was verified in this work that higher production values were obtained with wastewater applied with surface drip irrigation. When comparing the influence of the kind of water used in each system, the production values also were higher on wastewater irrigation with drip irrigation (surface and subsurface) and furrows. On microbiological quality, only the lettuce irrigated by subsurface drip irrigation and furrows showed safe contamination values to fecal coliform and Salmonella, according to... (Complete abstract, click electronic address below). / Mestre

Three field sites were chosen to study the environmental assimilative capacity of heavy metals in soil. These sites were the Werribee Farm and the Myome Farm in Australia and Shenyang Zhangshi Irrigation Area in China. The Werribee Farm and the Shenyang Zhangshi Irrigation Area received sewage treatment and application on land for a long time. The Myome farm is an experimental site in which investigations on land application of municipal wastewater on water repellent soils is currently being trailed. Heavy metal contamination, in particular Cr, Cu and Zn, in the Land Filtration soil of Werribee Farm was widespread. More than a century of sewage irrigation has occurred in the Werribee Farm. The temporal distribution pattern of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in the soil at this site follow an exponential trend with time and the spatial distribution pattern of accumulation of heavy metals in different paddocks correlates with the number of years of sewage irrigation at that site in the Farm. Extensive sewage irrigation at Shenyang Zhangshi Irrigation Area resulted in significant Cd pollution in soil-plant (rice) system and poses a significant threat to the health of local people. Even after eight years since cessation of sewage irrigation, the bioavailable fractions of Cd in the soil as analyzed by sequential extraction techniques were very high thus illustrating long-term persistence. The simultaneous competitive adsorption of metals in water repellent soils (at Myome Farm in South Australia) was studied. In the competitive situation, Cr, Pb and Cu are the heavy metal cations more strongly adsorbed by the soil, whereas Cd, Ni and Zn are the least adsorbed. The increase in Freundlich adsorption capacity by clay amendment suggested that clayed soils are capable sorption of higher heavy metal loadings compared to the non-clayed water repellent soil, which is more vulnerable to heavy metal inputs. A simple model of environmental assimilative capacity is proposed. The results of comparison of the three field sites shows that the Werribee Farm has a higher environmental assimilative capacity of heavy metals in soil than the soils at Shenyang Zhangshi Irrigation Area and Myome Farm, however heavy metal contamination at Werribee Farm is still a concern. The model of environmental assimilative capacity of heavy metals in soil is an effective tool to assist management of effluent applied land irrigation systems and can be used to better design environmental engineering systems.

Orientador: Bruno Coraucci Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-04T22:16:59Z (GMT). No. of bitstreams: 1 Bellingieri_PauloHenrique_M.pdf: 9365011 bytes, checksum: 6c7e81559cc6178c82c39aab2cd464f1 (MD5) Previous issue date: 2005 / Resumo: As águas subterrâneas representam a principal preocupação no processo de viabilização do reúso agrícola, como prática de pós-tratamento e disposição final de esgotos sanitários. O presente trabalho visa avaliar a possível contaminação gerada pela disposição controlada de efluente de tratamento secundário no cultivo de milho, e identificar a lâmina hídrica ideal para a irrigação da cultura, aliando as necessidades da engenharia sanitária com as da engenharia agrícola. Consistiu na análise de amostras do lençol freático, coletadas periodicamente durante duas saltas consecutivas, sendo uma na estação chuvosa e outra na estação seca. Os parâmetros analisados foram: pH, condutividade elétrica, Cr, Pb, Ni, Cd, Cu, Zn e N-N03-. Uma rede de poços de monitoramento foi instalada na área de pesquisa, contendo 10 poços locados a jusante de cada parcela para avaliação em função do risco à saúde pública. A variação do comportamento do lençol freático foi monitorada pela confecção de mapas potenciométricos sazonais e realização de slug test para obtenção da condutividade hidráulica dos poços de monitoramento. Os resultados permitiram concluir que a aplicação de efluentes sanitários na agricultura, via sulcos rasos, causou alguns impactos negativos às propriedades do solo e água subterrânea, além de proporcionar benefícios para a cultura, quando da reposição de água ao solo em períodos de estiagem / Abstract: Groundwaters represent the main concern in the process of viabilization of agriculture reuse, as practice of post-cure and final disposal of sanitary sewers. The present research aims to evaluate the possible contamination generated for the controlled disposal of the sewer of secondary treatment in the maize culture, and to identify the ideal hydric blade for the irrigation of the maize culture, uniting the necessities of sanitary and agricultural engineering. It consisted in the analysis of samples of the water table, collected periodically during two consecutive harvests, one in the rainy and another in the dry period. Were analyzed the following parameters: pH, electrical conductance, Cr, Pb, Ni, Cd, Cu, Zn and N-NO3 . A net of monitoring wells was installed in the research area, with 10 leased wells the downward of each parcel for evaluation in function of the risk to the public health. The variation of the behavior of the water table was monitored by the confection of potenciometric maps and accomplishment of slug test for attainment by the hydraulic conductivity of the monitoring wells. The results allowed to conclude that the application of sanitary effluent in agriculture, in saw ridges fIat, did not cause significant negative alterations in the properties of the ground and underground water, besides providing benefits for the maize culture, within of the replacement water soil in dry periods / Mestrado / Saneamento e Ambiente / Mestre em Engenharia Civil

Orientador: Roberto Testezlaf / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-22T21:34:01Z (GMT). No. of bitstreams: 1 Ribeiro_MayconDiego_M.pdf: 3280137 bytes, checksum: 9c253671fd642a329f3232738ee0af37 (MD5) Previous issue date: 2013 / Resumo: No cultivo em ambientes protegidos, o uso da irrigação é necessário, requerendo alta frequência e gerando dependência tecnológica do produtor na aplicação de água e fertilizantes. Irrigações inadequadas potencializam problemas, trazendo prejuízos financeiros pela baixa produtividade e desperdício de solução nutritiva (SN) e energia. Adicionalmente, o descarte inadequado desses insumos pode contaminar o solo e, consequentemente, o lençol freático. Estudos mostram que os sistemas de subirrigação têm potencial para obter altas eficiências na irrigação nesses ambientes, principalmente, quando há a recirculação da solução nutritiva. Porém, os equipamentos existentes atualmente no mercado foram desenvolvidos sem critérios de engenharia e produzidos em pequena escala para atender condições específicas de produção resultando em elevado custo inicial. Adicionalmente, a falta de conhecimentos sobre a sua aplicabilidade para diferentes sistemas de produção e sobre recomendações do manejo hídrico e nutricional para culturas distintas, proporciona outra limitação na sua aplicação, desencoraja sua adoção pelos produtores. O projeto e construção de uma mesa de subirrigação utilizando critérios de engenharia, que permitam o reuso da SN e o controle automático do manejo hídrico nutricional para diferentes culturas, disponibilizará um equipamento com potencial para ser inserido no mercado nacional de produção em ambientes protegidos. O objetivo desse trabalho foi projetar uma mesa de subirrigação automatizada com reuso da SN, a partir da aplicação de critérios de projeto de engenharia. Essa pesquisa foi dividida nas seguintes etapas: levantamento de informações sobre sistemas de subirrigação existentes no mercado, avaliação de campo de um sistema em operação, estabelecimento de parâmetros de dimensionamento por simulação, e a construção e avaliação de protótipo de equipamento. Os levantamentos realizados não localizaram fabricantes nacionais de equipamentos de subirrigação, e mostraram que os equipamentos em operação apresentavam projetos desenvolvidos empiricamente e construídos a partir de demanda específica do produtor. O sistema de subirrigação em operação avaliado apresentou baixa eficiência de irrigação e aplicação de água devido a perdas e ao descarte de SN. Os critérios adotados para o projeto da mesa de subirrigação foram ergonômicos e de segurança, funcionalidade e aplicabilidade, a escolha do material construtivo. A aplicação dos critérios adotados possibilitou o estabelecimento das seguintes características da mesa de subirrigação: largura de 1,58 m, comprimento variável, altura da borda de 0,06 m, chapa de poliestireno de alto impacto para a mesa e perfis de alumínio para a estrutura. A variação da combinação da vazão e do diâmetro do orifício de dreno associado ao controle automático do nível da lâmina na mesa de subirrigação atendem as exigências de manejo hídrico de diferentes culturas possibilitam a redução do uso de mão de obra e evita descartes com a recirculação da SN. Os resultados de avaliação da mesa de subirrigação construída permitiram identificar diferentes combinações de manejo associada à variação da altura e tempo de permanência da SN no interior da mesa. Concluiu-se que a mesa de subirrigação construída a partir de critérios de projeto de engenharia, com controle automático da reutilização da SN, tem potencial para ser inserido no mercado de ambiente protegido, tendo a opção de ser empregada em diferentes recipientes de produção, cultura e manejo / Abstract: Irrigation is a mandatory practice in greenhouse production, requiring high frequency and generating farmer technological dependency in water and fertilizers application. Low irrigation efficiencies increase production problems, bringing financial losses due to low yield and nutrient solution (NS) waste and energy cost. Additionally, the unsuitable disposal of these inputs can contaminate the soil and hence, the water resources. Studies showed that subirrigation systems have the potential for high efficiencies in greenhouse irrigation, especially when the recirculation of the nutrient solution is employed. However, subirrigation equipments currently available on the Brazilian market were designed without engineering criteria and produced on a small scale to meet specific production conditions, determining high initial investment cost. Furthermore, the lack of knowledge about its applicability to different production systems and water and nutritional management for distinct crops, provides another restriction in its application, and discourages producers in adopting this system. The design and construction of a subirrigation bench based on engineering criteria, enabling the NS reuse and the automatic control of water and nutrient management for different crops will provide a device with the potential to be introduced in the domestic market of greenhouse production. The objective of this work was to design an automated subirrigation bench with NS reuse, applying the fundamentals of engineering design criteria. This research was divided into the following steps: an information survey on commercial subirrigation systems, a subirrigation system field evaluation, and establishment of parameters for sizing simulation and the construction and evaluation of prototype equipment. The survey results do not tracked national companies that manufacture detailed subirrigation equipment, and shown that equipment found in farm operations was designed and developed empirically and constructed from specific producer demands. The evaluated subirrigation system revealed low values of irrigation and water application efficiencies due to NS losses and frequent disposal. The criteria adopted for the subirrigation bench design were based on ergonomic and safety, functionality and applicability issues, and the manufacture material selection. The implemented design criteria enabled the establishment of the following subirrigation bench features: width 1.58 m, length adjustable, edge height of 0.06 m, high impact polystyrene sheets for the bench frame and aluminum sheets for the supporting structure. The combinations of operation flow rate and drain orifice diameters, associated to the automated level control, allowed to establish water and nutrient management for different crops, reducing manpower needs and avoiding NS disposal due to the recirculated practice. The evaluation results of the assembled subirrigation bench showed that different management combinations can be performed by varying the NS depth and its residence time inside the equipment. It was concluded that the subirrigation bench constructed based on engineering design criteria, with automated management system and NS reuse, has the potential to be introduced in the greenhouse production market, with the option to be implemented to various crops and containers / Mestrado / Agua e Solo / Mestre em Engenharia Agrícola

Thesis (M. Sc. (Geography)) -- University of Limpopo, 2021 / Great interests in the geographical dimensions of poverty, food security, natural resources such as land and water, and livelihoods have been motivated by global efforts of reducing poverty and food insecurity, as part of the millennium development agenda. The achievement of household food security is a major concern facing the world at large, including South Africa due to the lack of land and water resources availability and accessibility. The study aimed at evaluating the potential reuse of greywater to improve household food security in two villages of Fetakgomo Local Municipality. The objectives of the study were to establish background characteristics, determine household food accessibility and availability, assess the reuse of greywater in relation to home gardening activities, ascertain the perceptions on greywater reuse and lastly to determine the household food security status of the households. The study adapted a mixed research approach and a 4% sample size was used. Ninety five and seventy eight households were randomly selected for Ga-Seroka and Ga-Nkwana villages, respectively. Data was collected using a structured questionnaire and the results were analysed using Statistical Package for the Social Sciences (SPSS) version-23 software. General Household Survey (GHS) in combination with Household Food Insecurity Access Scale (HFIAS) were used to assess household food security status of the two villages. The key results revealed that background characteristics of importance on greywater reuse include household size, educational level and employment status even though they varied in these two areas. Accessibility and availability of food was found to be more of a challenge in Ga-Seroka village than in Ga-Nkwana village. Respondents from Ga-Seroka village reused their greywater more as they drained it directly into their gardens. According to the HFIAS classification measure, 85% and 73% of households were categorised as least food insecure, 15% and 26% as medium food insecure and 0% and 1% as severely food insecure in Ga-Nkwana and Ga-Seroka villages respectively. Ga-Seroka village respondents preferred to reuse their greywater more often as compared to respondents in Ga-Nkwana village and were not reluctant to use it in their gardens. In conclusion, reuse of greywater has a potential to improve household food security. There is a need for the government to subsidize the households with incentives such as quality seeds and fertilizers in order to enhance their productivity and thus improving their household food security. Keywords: Food security, availability, accessibility, land, water, Fetakgomo Local Municipality, greywater reuse. / National Research Foundation (NRF)

published_or_final_version / Architecture / Master / Master of Landscape Architecture

Darvill Wastewater Works (DWWW) receives and treats both domestic and industrial wastewater from the city of Pietermaritzburg, in KwaZulu-Natal. Sludge from the wastewater treatment is sprayed onto surrounding lands, causing odour and fly problems. The plant also discharges treated effluent into the Msunduzi River, compromising water quality. This study uses several economic valuation techniques to estimate the value of the benefits of improving air and water quality to overcome these problems caused by DWWW. The benefits. are then compared with the costs of upgrading DWWW to see whether or not upgrading DWWW to improve air and water quality would be worthwhile. The Contingent Valuation Method (CVM) was used to elicit people's willingness to pay (WTP) for improvements in air quality due to the elimination of odours and flies caused by sludge deposited by DWWW. The WTP estimates reflect individual's preferences for improvements in air quality. The stated WTP amounts were positively related to household income, but negatively related to the age and gender of the respondent and the number of dependants in the household. The mean monthly WTP for the surveyed households is higher for those that are closer to the pollution source (R23.00 and R29.00 for Zones land 2) and less for those further away (RI4.00 for Zone 3). Sobantu residential area had the lowest mean monthly WTP (R18.00), followed by Lincoln Meade (R27.00) and Hayfields (R54.00). This is expected, as Sobantu has relatively high levels of unemployment and lower household incomes. Strategic, hypothetical and free rider bias may have led to the unexpected signs of some estimated regression coefficients in linear regression models used to estimate WTP. The mean WTP was estimated as R307.20 per annum per household, and when this is aggregated over the total population in the residential areas impacted by odours and flies (37192 households), the benefits of eliminating odours and flies are estimated as R11 425 382.00 per annum. A hedonic price method was used to quantify the decline in property values as a result of odours and flies caused by sludge deposited by DWWW. Properties experienced a R6650.08 decline in selling price if the distance from them to DWWW is decreased by one kilometre. Properties that are closer to DWWW were worth RI5 953.90 less than those further away from DWWW. Aggregating these values over all estimated impacted households in the study, gives an estimated benefit of improving air quality of R28 480 518.00 per annum. The impact of water pollution was quantified by estimating the revenue (R3 744 975.00) that would be lost by Pietermaritzburg if the Duzi Canoe Marathon were to be cancelled due to incidences of diarrheoa reported during the race. A cost of illness procedure was adopted to quantify the effect of water pollution on the health of communities that use the Msunduzi River as a source of potable water supply. A value of R1 243 372.50 was estimated as the annual cost of water-related illnesses in these rural areas. This value represents the costs of the river pollution to those communities. Both of these exercises indicated that improving water quality of the Msunduzi River would be beneficial to society. The effect of nutrient enrichment of the Msunduzi River was quantified by estimating the cost of removing water hyacinth from the Inanda Dam, treatment cost at Wiggins water treatment works and the value of recreation at Mahlabathini Park (Inanda Dam). The annual cost of removing water hyacinth was estimated from the direct costs of chemicals and labour as R47 202.15. The increased treatment costs at Wiggins attributable to DWWW were estimated as R1 104 999.20 and R956 924.15 per annum for removal of algae, and tastes and odours, respectively. The value of R706.90 per annum was estimated as the consumer surplus accruing to recreationists, and, therefore, the value of recreation at Mahlabathini Park to an individual. These annual benefits, when aggregated over the total study population (296 590) were over two hundred million rands (R209 659 470.00). The estimated total benefits (R256 662 840.00) of eliminating odours and flies and effluent problems were compared to the actual costs of two alternative methods of upgrading DWWW using cost-benefit analysis. These alternatives were co-disposal option (R170 473 320) and a land disposal option (R168 809377). Benefit-cost ratios of 1.51 and 1.52 suggest that from society's standpoint, it would be beneficial to upgrade the plant in order to eliminate its adverse environmental impacts. The study results have important implications for policy makers, both the DWWW management and the Pietermaritzburg-TLC municipality. At present DWWW is operating beyond its design capacity, and this problem, together with the poor status of Pietermaritzburg's reticulation system, causes overflow of untreated or compromised final effluent into the Msunduzi River during rainy seasons. These problems also impact on the efficient operation of the plant as the sludge is not properly digested before being sprayed onto surrounding land. Thus to prevent further environmental degradation, a fundamental basis of the National Environmental Management Act, DWWW would need to address these issues. Upgrading DWWW would be a short-term solution if the problems with the storm-runoff into the plant is not addressed. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.