ABSTRACT Constructed wetland systems have been used to treat different wastewater; among their essential components are the cultivated plant species and type of substrate used to fill them. The choice of plant species and type of substrate are important for the good system performance in wastewater treatment. This study aimed to evaluate the extraction capacity of Napier and Tifton 85 grasses when cultivated at different positions in horizontal subsurface flow constructed wetlands (HSSF-CWs) filled with different substrates in wastewater treatment from a bulk milk-cooling tank (MTWW). The experimental unit consisted of four HSSF-CWs, in which an average surface organic loading rate of 318 kg ha−1 d−1 of BOD5,20 was imposed and a hydraulic holding time of 1.8 and 3.0 d, respectively, in units filled with gravel or crushed PET bottles. Tifton 85 grass presented the highest Na extraction capacity, with better results obtained in HSSF-CWs filled with crushed PET bottles, while Napier grass was more effective in extracting N, K, and P from MTWW. When cultivated in the second half of gravel-filled HSSF-CWs, both grasses provided higher average N extractions when compared to those filled with crushed PET bottles, which had higher extractions in the first half of HSSF-CWs.

ABSTRACT Knowing the relationship between the total suspended solids concentration (TSS), turbidity in the waters, and that turbidity analysis can be done faster and in less expensive way, this study aimed to obtain mathematical model to estimate the total suspended solids (TSS) concentration from the turbidity values for waters of Doce river basin. For this purpose, it was used the water quality database of the Minas Gerais Institute of Water Management (IGAM). The data were pre-treated using the adjusted boxplot technique followed by adjustment of curves for the different management units and rainfall regime period. It was verified the possibility of a single curve through the dummy variable technique, subsequently. With the results it was observed that the adjusted boxplot technique proved to be useful for environmental data. Linear relationships with R2 values, as a rule, were higher than 0.6, however, it was not possible to develop a single model. It is concluded that the generated models presented good adjustments being able to be used for predicting the concentration of TSS as a function of turbidity. However, each management unit in each period of rainfall regime presents particularities that were reflected in the prediction models.

ABSTRACT The achievement of all the water quality parameters that constitute the water quality indices can be a hamper to their use. The objective of this study was to analyze the viability of using minimum indices to monitor water quality, comparing different methods. For this purpose, the Environmental Company of the State of São Paulo database for the year 2016 of the Tietê/Jacaré and the Tietê/Batalha units was used. Four indices present in the literature were compared with the indices currently practiced in the states of São Paulo and Minas Gerais (“standard indices”). For feasibility analysis, the indices were classified by the “standard indices” methods and compared to them. The minimum indices were significantly correlated with the “standard indices”, from moderate to strong degree. The minimum indices, as a rule, overestimated water quality when compared to the index of the state of Minas Gerais; and underestimated when compared to the index of the state of São Paulo. It is concluded that the minimum indices are useful and practicable tools, with respect to the use of the WQI for management purposes. However, such indices should be evaluated periodically to avoid making mistaken decisions.

ABSTRACT We aimed to evaluate the efficiency of six different horizontal subsurface flow constructed wetlands (HSSF-CWs), with different substrates (gravel and crushed PET bottles), which also varied in relation to the presence and arrangement of plant species (elephant grass and Tifton 85 bermudagrass) in the removal of pollutants from a bulk milk cooling tank (MTWW). Each bed was fed at a flow rate of 0.18 m3 d-1 and average organic load rate (OLR) of 318 kg ha-1 d-1 of BOD5, with hydraulic detention time (HRT) of 1.84 days in the gravel-filled HSSF-CWs (CWS-G) and 2.97 days in the PET-filled HSSF-CWs (CWs-P). The CWs-P were as efficient as the CWs-G in the removal of BOD5, COD, Total-P, and K-Total, being in some cases even more effective (turbidity, TS, TSS and Na). The gravel, on the other hand, provided greater removals of Total-N from the MTWW. In the non-cultivated CWs and those cultivated with elephant grass, in its first half and Tifton 85 grass in its second half, there were higher average efficiencies in COD and TSS removal sand, in the latter, the highest average removal of Total-N.

RESUMO Objetivou-se neste trabalho avaliar a remediação de água contendo o inseticida clorpirifós, por meio de sistemas alagados construídos (SAC) cultivados com as espécies Polygonum punctatum, Cynodon spp. e Mentha aquatica operados sob diferentes tempos de retenção hidráulica: 24, 48, 96, 144 e 192 h. A eficiência do sistema foi baseada na redução da concentração inicial do clorpirifós e toxicidade da água contaminada. Os resultados mostraram que os sistemas alagados construídos são uma excelente alternativa na biorremediação do inseticida clorpirifós no meio aquoso. Observou-se média geral de eficiência na remoção do inseticida de 98,6%, sendo que no primeiro tempo de retenção hidráulica, 24 h, houve remoção do clorpirifós para valores inferiores ao limite detecção para todos os SAC. Tal resultado é atribuído principalmente aos processos de adsorção e degradação microbiana. Para os ensaios padronizados qualitativos de toxicidade aguda com Daphnia similis, para a maioria das amostras observou-se a redução de toxicidade acima de 80%. Constatou-se que os testes ecotoxicológicos com os efluentes dos sistemas alagados construídos estudados são uma boa opção como indicativo da eficiência dos tratamentos e uma promissora alternativa na complementação de análises físicas e químicas.

ABSTRACT The objective of this study was to evaluate the remediation of water containing the insecticide chlorpyrifos by using constructed wetlands (CW) cultivated with Polygonum punctatum, Cynodon spp. and Mentha aquatica, operated under different hydraulic retention times: 24, 48, 96, 144 and 192 h. The system efficiency was based on reduction of the initial concentration of chlorpyrifos and toxicity of the contaminated water. The results showed that constructed wetlands are an excellent alternative for remediation of the insecticide chlorpyrifos in aqueous medium. It was observed that the average overall removal efficiency of the insecticide was 98.6%, and in the first hydraulic retention time, 24 h, chlorpyrifos was removed to levels below the detection limit in all CW. This result is mainly attributed to adsorption and microbial degradation. For the qualitative standard acute toxicity tests with Daphnia similis, for most samples there was a reduction in toxicity greater than 80%. It was reported that the ecotoxicological tests with the effluents of the constructed wetland are a good option as an indicator of the effectiveness of treatments and a promising alternative to complement the physical and chemical analyses.

ABSTRACT This study aimed to characterize the material composition responsible for clogging the porous medium of horizontal subsurface flow constructed wetland (HSSF–CW) systems, which is detrimental to a proper system operation. Six completely clogged HSSF–CWs were used after treatment of swine wastewater. Operating conditions of these systems were named CW–C (HSSF– CW 1 and HSSF–CW 4, non-cultivated, i.e. controls), CW–T (HSSF–CW 2 and HSSF–CW 5, cultivated with Tifton 85 (Cynodon spp.)), and CW–A (HSSF–CW 3 and HSSF–CW 6, cultivated with alligator weed (Alternanthera philoxeroides)). The results showed that most of the clogging material was composed of total fixed solids (95, 84, and 82% in CW–C, CW–T, and CW–A, respectively). However, total volatile solids (TVS) mostly affected pore clogging. The larger accumulations and productions of TVS in CWs might have originated from dead plants.

ABSTRACT We evaluate the application of treated sanitary wastewater (TSW) to provide potassium for crops and reduce demand for fresh water and mineral nutrients. The field experiment was arranged in randomized block design with four replications and five treatments: 50, 100, 150 and 200% of potassium requirements and a control with conventional fertilizer. The TSW was applied to maize (November 2012 to February 2013), cotton (June to November 2013) and bean (April to June 2014). After bean, soil chemical properties were evaluated until 0.8 m depth. Fertigation with TSW to potassium fertilization provided about 50% of water, nitrogen and phosphorus to the bean. The soil nutrient availability and soil organic matter did not increase, whereas sodium had linear increased with TSW levels in investigated soil depth. Soil pH showed same behavior that sodium, with the highest pH level of 6.5 in 0-0.2 m soil layer. Soil nutrients and organic matter did not increase with TSW doses up to 0.8 m depth. Soil pH and sodium had linear increasing with TSW doses, respectively up to 0.6 and 0.8 m soil depth. Fertigation with potassium recommendation also provided a high content of sodium, threatening the balance of soil-plant system with continuous use. The sodium should be the first reference to permanent wastewater reuse in agriculture.

ABSTRACT Many modifications in hydrodynamic conditions occur inside the bed of a horizontal subsurface flow constructed wetland (HSSF–CW) in operation. Studies on hydraulic conductivity measurement techniques in HSSF–CW are imperative since the monitoring of flow conditions is essential for understanding and controlling its clogging. This study aimed to assess the hydrodynamic behavior in HSSF–CW by means of saturated hydraulic conductivity (Ks) analysis. For this, six HSSF–CW were used: two non-cultivated (control), two cultivated with Tifton 85 (Cynodon spp.), and two cultivated with alligator weed (Alternanthera philoxeroides). Application of swine wastewater (SW) in HSSF–CW started on June 15, 2011, with Ks measurement period between September 9 and November 11, 2011, in which five measurements were performed in different positions along the system length and over experimental period in order to assess the effects of vegetation, position, and time factors on this variable. Ks values ranged from 1,392 to 2,834 m d−1. Plant presence led to Ks decreasing in the systems, but cultivated species had no influence on this variable. Monitoring time of HSSF–CW was no longer enough to provide a reduction in Ks, at 10% probability level.

ABSTRACT Swine wastewater have high pollution load, requiring treatment before its disposal into the environment. Methane (CH4) potentially emitted for such waste is considered 21 times more polluting than Carbon dioxide (CO2), and the nitrous oxide (N2O) is considered 310 times. In this way, projects of the Clean Development Mechanism (CDM) and energy use related to the CH4 are worldwide diffused. It was evaluated the potential greenhouse gas emissions in the influent and effluent from digesters and stabilization ponds used to treat the swine wastewaters in two commercial farms operating in full cycle, located in the municipality of Oratorios-MG, Brazil. Using the methodology “AM0006” to estimate the average potential of greenhouse gases, it was identified 55% and 23% of reduction in emissions from digesters and stabilization ponds, respectively. Thus, when comparing the two systems, in the conditions that they were operated, it can be concluded that the digestion treatment system was more suitable for the treatment of swine wastewater, when taking into account only the emission of the mentioned gases, subjects of this study.

ABSTRACT This study aimed to monitor degradation of compost from undigested sewage sludge disposed on soil surface or incorporated it. The sewage sludge was blended with wood sawdust during a 90-day composting to achieve a C/N ratio of 9. Each waste was dosed based on its total content of nitrogen and on an annual dose of 500 kg ha-1, which is broadly recommended for forage fertilization. After incorporation and surface applied (five replicates each), waste mineralization was monitored for 131 days by samplings taken from both conditions for further analyses. The samples were measured for total organic carbon (TOC); easily oxidizable carbon (OOC); total nitrogen (TN); ammonia and nitric nitrogen, and from them the total organic nitrogen (ON); volatile solids; and water content. The findings pointed to a decrease in TOC, OOC and ON contents throughout monitoring, regardless of disposal method, however, most remarkable whether incorporated to the soil, computing mineralization rates above 87%.

RESUMO Problemas decorrentes da descarga de esgoto sanitário em rios são fatores preocupantes, por reduzir a qualidade da água, principalmente na região semiárida. Como alternativa viável, a utilização agrícola de águas residuárias pode minimizar problemas ambientais e fornecer nutrientes bem como parte da exigência hídrica de plantas cultivadas. Assim, objetivou-se verificar a influência da água residuária sanitária tanto na forma bruta (ARB) quanto na tratada, em nível terciário (ART), em substituição à adubação potássica mineral em cobertura, sobre os indicadores de produção e qualidade tecnológica da fibra do algodoeiro NuOpal BG RR®. O experimento foi conduzido em Janaúba - MG, no delineamento em blocos casualizados, constituído por 5 tratamentos (T0: Água limpa e adubação mineral; T1: 100% e T2: 150% de ART no fornecimento do K em cobertura; T3: 100% e T4: 150% de ARB no fornecimento do K em cobertura), com quatro repetições. Pode-se substituir a adubação potássica em cobertura aplicando 100% da dose potássica recomendada via ART, sem afetar a produtividade e a qualidade da fibra, sendo complementada a cobertura nitrogenada. Ao se empregar a ARB, além de não afetar a qualidade da fibra, há incremento de até 43,6% na produtividade do algodão, sendo dispensada a cobertura nitrogenada.

ABSTRACT Sewage discharge into rivers cause troubles by deteriorating water quality, mainly in the semi-arid region. The agriculture reuse of wastewater is an alternative to minimize environmental problems, provide nutrients and part of water requirements to crops. The purpose of the current study was to verify the influence of raw sanitary wastewater (ARB) and tertiary treated sanitary wastewater (ART) replacing potassium topdressing in cotton fertigation, investigating changes in the yield and fiber quality indexes of cotton NuOpal BG RR®. The field experiment was developed in Janaúba, Minas Gerais State, Brazil, in randomized complete block design with five treatments (T0: drinking water and mineral fertilizer; T1 and T2: 100% and 150% of potassium topdressing requirements supplied by ART; T3 and T4: 100% and 150% of potassium topdressing supplied by ARB) and four replications. The T1 do not change cotton yield and fiber quality, once nitrogen topdressing is performed. The ARB not affect cotton fiber quality and improve yield by 43.6%, being unnecessary nitrogen topdressing.

RESUMO Neste trabalho, teve-se como objetivo o ajuste de equações que possibilitassem a estimativa do gradiente de pressão estática do ar, quando insuflado em camadas de resíduos orgânicos misturados com diferentes proporções de cama de frango. As medições do gradiente de pressão estática do ar foram realizadas em um protótipo, submetido a vazões específicas, que variaram de 0,02 a 0,13 m3 s-1 m-2, em camadas de bagaço de cana-de-açúcar, palha de café e serragem de madeira, misturadas com cama de frango, nas proporções de 0; 10; 20; 30 e 40% (base volumétrica). Os dados de gradiente de pressão estática do ar e vazão específica ajustaram-se bem aos modelos de Shedd, Hukill & Ives e Hunter, podendo ser utilizados para predizer o gradiente de pressão estática do ar ao ser insuflado em camadas de resíduos orgânicos. Menores valores de gradientes de pressão estática do ar foram obtidos em camadas sem adição de cama de frango e os maiores gradientes obtidos nas camadas constituídas pela mistura com cama de frango, na proporção de 40%.

ABSTRACT This study aimed at fitting equations for estimation of the static pressure gradient of the air flow applied through layers of organic waste mixed with different proportions of poultry litter. Pressure gradient was measured by a specific prototype submitted to discharges between 0.02 to 0.13 m3 s-1 m-2. The measures were taken in layers of sugarcane bagasse, coffee straw and sawdust mixed with poultry litter in ratios of 0, 10, 20, 30 and 40% (at a volume basis). The three models Shedd, Hukill & Ives and Hunter were fitted to the experimental data for prediction of the pressure gradient and the airflow rate. Lower static pressure gradient was observed in layers without poultry litter addition and higher ones were seen in layers with 40% poultry litter.

RESUMO A colmatação é um fenômeno intrínseco aos sistemas alagados construídos (SACs) utilizados no tratamento de esgotos, sendo decorrente dos mecanismos de remoção de poluentes. Dentre os métodos disponíveis para a avaliação da colmatação, destaca-se o uso de traçadores para a obtenção das condições hidrodinâmicas dos SACs. No entanto, não há um traçador ideal; os salinos, por exemplo, são passíveis de absorção, mecanismo influenciado pelo estádio no qual a planta se apresenta. Assim, objetivou-se, com a realização do trabalho, avaliar a utilização do NaCl para caracterização do grau de colmatação e das condições hidrodinâmicas de SACs de escoamento horizontal subsuperficial, plantado e não plantado, verificar a confiabilidade do uso desse traçador em testes executados durante o estádio de crescimento (após o corte da parte aérea) e o florescimento da taboa (Typha latifolia), além da suscetibilidade de causar danos às plantas. Os resultados indicaram que o NaCl pode ser utilizado para estudos de comparação do grau de colmatação de SACs, inclusive não apresentando danos à taboa. Verificou-se que, após sete anos de operação, a unidade plantada encontra-se mais colmatada e com regime de escoamento mais turbulento. Também foi possível inferir que o corte das plantas propiciou aumento na dispersão no sistema.

ABSTRACT Clogging is an intrinsic phenomenon of constructed wetland systems (CWs) used in sewage treatment, and resulting from pollutant removal mechanisms. Among clogging evaluation methods, tracers may be highlighted since they can used to determine CW hydrodynamic conditions. However, there is no ideal tracer; saline ones, for example, are able to be absorbed, which is influenced by plant stage. Thus, this study aimed to assess the use of NaCl to characterize the clogging degree and hydrodynamic conditions in subsurface horizontal flow constructed wetland, with or without cropping, as well as check this tracer reliability under tests during southern cattail (Typha latifolia) growth stage (after shoot cutting) and flourishing, as well as its ability to damage the plants. The results showed that NaCl could be used for studies comparing the degree of clogging of CWs, aside from presenting no damage to cattail. It was found that after seven years operating, cropped area is further clogged and has more turbulent flow. It was also possible to infer that plant cuttings led to increased dispersion within the system.

RESUMO Objetivou-se, neste trabalho, estudar o processo de decomposição do carbono (CO) e nitrogênio orgânico (NO) dos resíduos da pupunheira, em condições de campo e laboratório, e em duas formas de aplicação: com incorporação ou em disposição superficial no solo. O experimento de campo foi conduzido em Cambissolo Háplico Tb distrófico latossólico (CXbd), nas condições climáticas tropicais do período de primavera/verão, na cidade de Viçosa-MG, Brasil. Os resíduos foram incubados em condição de campo e laboratório, durante 112 dias, período no qual foram retiradas amostras para a análise das concentrações mineralizadas do CO e NO. A degradação do resíduo foi mais intensa em condição de campo que na de laboratório, e a incorporação do resíduo no solo acelerou a degradação nas duas condições de incubação do material. Os métodos utilizados para a estimativa dos coeficientes e frações de mineralização do CO e disponibilização do nitrogênio inorgânico, em condição de laboratório, geraram resultados condizentes com os obtidos na condição de campo, contudo subestimaram consideravelmente os valores obtidos.

ABSTRACT The objective of this study was to evaluate organic carbon (OC) and organic nitrogen (ON) decomposition in peach palm waste under field and laboratory conditions. Application was performed by both incorporating and releasing the waste onto soil surface. Field experiment was carried out on an Inceptisol under tropical conditions during the spring and summer seasons in Viçosa - MG, Brazil. The waste was incubated under field and laboratory conditions for 112 days within which samples were taken for analysis. We noted that waste was more intensely degraded under field conditions than in lab environment. Moreover, waste incorporation into soil accelerated the degradation under both incubation conditions. The estimation methods for coefficients and fractions of OC mineralization, inorganic nitrogen availability under lab condition produced results consistent with field ones; however, they were considerably underestimated.

RESUMO Objetivou-se, com a realização deste trabalho, determinar a eficiência de aeração e a capacidade do sistema de aeração em cascata em remover matéria orgânica da água residuária do processamento dos frutos do cafeeiro (ARC). O sistema de aeração foi constituído por cascata com 4,14 m de altura, distribuída em 23 degraus (altura, largura e comprimento de 0,18; 0,32 e 0,60 m, respectivamente), reservatório para a recepção/detenção da ARC escoada, por três horas, e reservatório de distribuição, de onde era recirculada no sistema. Durante a fase experimental, o sistema de tratamento ficou em operação por trinta dias, sendo a ARC recirculada três vezes por dia, numa vazão constante de 1 L s-1, e substituída a cada dez dias. A cada recirculação, amostras do afluente e efluente foram coletadas e analisadas. Com a utilização do sistema de aeração em cascatas, foi possível incorporar, em média, 0,2 mg L-1 de oxigênio a cada lance de 1 m de degraus na cascata. A eficiência de aeração na cascata foi de 0,128 ou 0,141, dependendo se foi considerado ou não o efeito salino na ARC. A alta concentração de material orgânico não permitiu que se detectassem grandes alterações na concentração de oxigênio dissolvido na ARC. O tempo de detenção ideal da ARC no tanque de recepção/detenção foi de 26 min.

ABSTRACT This study aimed at assessing the efficiency of aeration and organic matter removal of a cascade aeration system treating wastewater derived from coffee fruit processing (CW). The system consisted of one 4.14-m cascade with 23 steps (height, width and length of 0.18, 0.32 and 0.60 m, respectively), one receiving tank to store CW for three hours and one distribution tank, from which it was recirculated through the system. The system remained operating for thirty days during which CW recirculated three times a day under a constant flow rate of 1 L s-1 and being replaced every ten days. In each recirculation cycle, samples of effluent and affluent were collected and analyzed. The cascade aeration system incorporated an average of 0.2 mg L-1 of oxygen every one meter of cascade steps. The aeration efficiency was 0.128 or 0.141 depending whether or not salt effect on CW was considered. The high concentration of organic material in CW hampered the detection of major changes in dissolved oxygen contents. We also found that 26 minutes was the ideal time to maintain CW in the receiving tank.