Avaliação ecotoxicológica de efluentes tratados por alagados construídos / Ecotoxicological evaluation of effluents treated by constructed wetlands

RESUMO O objetivo deste trabalho foi avaliar o desempenho de alagados construídos com fluxo subsuperficial horizontal cultivados com as macrófitas aquáticas Eleocharis sp. (junco) e Typha sp. (taboa) na redução da toxicidade de efluentes domésticos. Para isso, foram utilizados ensaios ecotoxicológicos com o microcrustáceo Daphnia similis, a dicotiledônea Lactuca sativa (alface), a monocotiledônea Sorghum vulgare (sorgo) e as macrófitas aquáticas Lemna sp. (lentilha-d'água) e Azolla sp. O efluente doméstico mostrou-se tóxico à Daphnia similis com média de EC50 de 1,3%. Os tratamentos com macrófitas reduziram significativamente a toxicidade do efluente, com médias de EC50 de 73% para o tratamento com junco, 53,17% para o com taboa e 78,25% para o com taboa + junco. O controle (sem macrófitas) também reduziu significativamente a toxicidade, com média de EC50 de 63,13%. Nos ensaios de fitotoxidade, a alface e o sorgo não se mostraram sensíveis ao efluente analisado, embora sejam para outros tipos de efluentes. A macrófita Lemna sp. também não foi sensível ao efluente estudado, no entanto, observou-se a capacidade de identificar, com essa espécie, o potencial eutrofizante do efluente, já que esta se desenvolveu melhor no efluente bruto do que nos tratados. Com a macrófita Azolla sp., foi possível verificar que o efluente bruto apresenta maior potencial eutrofizante se comparado com os tratamentos com junco, taboa e controle, nos quais houve remoção de nitrogênio e fósforo. No entanto, evidenciou-se efeito tóxico para Azolla sp. nos efluentes tratados.

ABSTRACT The research objective was to evaluate the performance of wetlands constructed with vertical sub-surface flow cultivated with Eleocharis sp. (Junco) and Typha sp. (Taboa). For this, ecotoxicological tests were used with the microcrustacean Daphnia similis, with the dicotyledon Lactuca sativa (alface), the monocotyledon Sorghum vulgare (sorgo) and the aquatic macrophytes Lemna sp. (Duckweed) and Azolla sp. The domestic effluent was toxic to Daphnia similis with a mean EC50 of 1.3%. Macrophyte treatments significantly reduced effluent toxicity with EC50 averages of 73% for junco treatment, EC50 53.17% for taboa treatment, and EC50 78.25% for taboa + junco treatment. The control (without macrophytes) also significantly reduced toxicity, with a mean EC50 of 63.13%. In the phytotoxicity tests, lettuce and sorgo were not sensitive to the analyzed effluent, although they were for other types of effluents. The macrophyte Lemna sp. was also not sensitive to the effluent studied. However, it was possible to identify the eutrophic potential of the effluent with this species, since it was better developed in the raw effluent than in treated ones. With the macrophyte Azolla sp., it was possible to verify that the raw effluent has greater eutrophic potential when compared to the treatments with junco, taboa and control, where nitrogen and phosphorus removal was observed. However, toxic effect was observed for Azolla sp. in treated effluents.

Biological characteristics and lytic effectiveness of phages isolated from domestic wastewater against indigenous Salmonella spp

Aim: This study was carried out to isolate and study the effectiveness of lytic phage from domestic wastewater to reduce the population of Salmonella spp. in patients suffering from diarrhea and to characterize biological phages. Methodology: The lytic phages from several domestic wastewater were identified using a transmission electron microscope to know morphological phages. After identifying the molecular weight protein by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, to know the effectiveness, the lytic phages were infected to Salmonella spp. from diarrheal disease patients and non-pathogenic Escherichia coli. Phage stability on thermal, pH, and buffer was then analyzed to determine the biological characteristics. Results: Three lytic phages (F-SB1, F-SB2, and F-SB3), successfully isolated from domestic wastewater, showed an icosahedral head with a short or long tail as their morphological characteristic. These phages were morphologically similar to the phages of family Siphoviridae, Myoviridae and Podoviridae. The three isolated lytic phages were stable at 27 °C to 37 °C, pH 4-7 in sodium magnesium buffer and effectively decreased the population of Salmonella spp., however could not lyse E. coli. Interpretation: All the isolated lytic phages in this study can contribute as cocktail phages in decreasing the population Salmonella spp

Avaliação do desempenho de sistemas alagados construídos de escoamento horizontal subsuperficial tratando efluente de reator UASB, com base em quatro anos de monitoramento / Performance evaluation of horizontal subsurface flow constructed wetlands in the treatment of UASB reactor effluent, based on four years of monitoring

RESUMO Um sistema composto por um reator anaeróbio tipo upflow anaerobic sludge blanket (UASB), seguido de um sistema de alagados construídos (SAC) de escoamento horizontal subsuperficial compreendendo duas unidades em paralelo (50 habitantes cada), foi avaliado para o tratamento de águas residuárias geradas na cidade de Belo Horizonte, Minas Gerais, Brasil. Uma unidade foi plantada com Typha latifolia e a outra não foi vegetada. Amostras semanais do efluente do reator UASB e do efluente das unidades do SAC foram avaliadas por um período de quatro anos de operação do sistema. Nas taxas de aplicação praticadas (média de 0,11 m3.m-2.d-1), o efluente final apresentou excelente qualidade em termos de matéria orgânica e sólidos suspensos, mas baixa capacidade de remoção de nitrogênio. Os valores médios de concentração no efluente das unidades plantadas e não plantadas foram, respectivamente, demanda bioquímica de oxigênio: 25 e 23 mg.L-1; demanda química de oxigênio: 50 e 55 mg.L-1; sólidos suspensos totais: 10 e 8 mg.L-1; nitrogênio Kjeldahl total: 30 e 31 mg.L-1; e nitrogênio amoniacal: 27 e 28 mg.L-1. Não se observou diferença significativa entre as concentrações efluentes das unidades plantada e não plantada para a maioria dos constituintes investigados.

ABSTRACT A system composed of an upflow anaerobic sludge blanket (UASB) reactor followed by two horizontal subsurface flow wetlands (50 inhabitants each) constructed in parallel was evaluated for the treatment of municipal wastewater generated in the city of Belo Horizonte, Minas Gerais, Brazil. One unit was planted with Typha latifolia, and the other one was not planted. Weekly samples of the effluent from the UASB reactor and the effluent from both wetland units were evaluated for a period of four years of the system's operation. With the applied loads (average of 0.11 m3.m-2.d-1), the final effluent showed excellent quality in terms of organic matter and suspended solids, but it showed low capacity for nitrogen removal. Mean concentration values in the effluent from the planted and unplanted units were, respectively, biochemical oxygen demand: 25 and 23 mg.L-1; chemical oxygen demand: 50 and 55 mg.L-1; total suspended solids: 10 and 8 mg.L-1; total Kjeldahl nitrogen: 30 and 31 mg.L-1; and N-ammonia: 27 and 28 mg.L-1. There was no significant difference between the effluent concentrations from the planted and unplanted units for most of the evaluated constituents.

Avaliação da eficiência do tratamento de esgoto doméstico pelo teste do micronúcleo em Oreochromis niloticus (Cichlidae) / Evaluation of the domestic wastewater treatment efficiency by micronucleus test on Oreochromis niloticus (Cichlidae)

RESUMO Este estudo teve por objetivo avaliar a eficiência no tratamento do esgoto doméstico de uma cidade do interior paulista, pela análise de micronúcleos e anormalidades nucleares nos eritrócitos de tilápias expostas ao efluente bruto e ao tratado. Duas coletas foram realizadas: uma na estação chuvosa e outra na estação seca. Foram utilizados três aquários de 20 L nos experimentos, com cinco peixes cada. No primeiro, os animais foram expostos à água de poço artesiano (controle negativo); no segundo, ao esgoto bruto diluído; no terceiro, ao esgoto após tratamento. Decorrido o tempo de exposição (72 h), coletou-se o sangue desses animais para obtenção de lâminas de esfregaço. Os resultados obtidos mostraram efeitos genotóxicos e mutagênicos do efluente bruto, em ambas as coletas; porém, esses efeitos não foram significativos após o tratamento do esgoto, o que mostra que o processo utilizado no tratamento foi eficiente para minimizar tais efeitos.

ABSTRACT This study aimed at evaluating the efficiency in the domestic wastewater treatment from a city of Sao Paulo State (Brazil), by micronuclei and nuclear abnormalities analysis in erythrocytes of tilapias exposed to raw and treated wastewater. Two samples were collected. Three aquariums of 20 L, with five fish each, were used in the bioassays. In the first, the animals were exposed to the artesian water (negative control); in the second, to the diluted raw wastewater; and in the third, to after wastewater treatment. After the exposure time (72 h), the blood was collected for preparing the smear slides. The results showed genotoxic and mutagenic effects of the raw wastewater in both samples, showing that the process used was efficient to minimize these effects.

Inmovilización microbiana en polímeros sintéticos para el tratamiento de aguas residuales / Microbial immobilization on synthetic polymers for wastewater treatment

Objetivo. Evaluar la capacidad de inmovilización microbiana de algunos polímeros sintéticos, y establecer su desempeño durante la partida y operación de un reactor biológico híbrido (RBH), aplicado al tratamiento de aguas residuales domésticas. Métodos. Para la evaluación fueron seleccionados cinco polímeros: tereftalato de polietileno (PET), polibutadieno (BD), espuma de poliuretano (EPU), poliestireno expandido (EPS) y polietileno (P). Los materiales con mayor capacidad de inmovilización (expresado como la cantidad de unidades formadoras de colonias contenidas en un gramo de material, UFCg-1), fueron incorporados a un RBH, con volumen operacional de 10,4L, alimentado con agua residual sintética. La eficiencia del sistema fue establecida en términos de remoción de la materia orgánica contenida en el afluente durante 13 días de operación continua. Resultados. Los polímeros que presentaron mayor capacidad de inmovilización fueron: BD (2,2x10(7) UFCg-1) y EPU (4,6x10(7) UFCg-1). El RBH, sometido a una carga orgánica volumétrica de 2,7 Kg DQO m-3d-1, presentó estabilidad operativa en todos los tratamientos evaluados, alcanzando una remoción de materia orgánica de 78% y 94%, al emplear BD y EPU como soportes de inmovilización, respectivamente.

Objective. Evaluate the ability of microbial immobilization of several synthetic polymers, and establish its performance during the start-up and operation of a hybrid biological reactor (HBR), applied to domestic wastewater treatment. Methods. For evaluation we selected five polymers: polyethylene terephthalate (PET), polybutadiene (BD), polyurethane foam (PUF), expanded polystyrene (EPS) and polyethylene (PE). Materials with higher immobilization capacity (expressed as the number of colony forming units contained in one gram of material, CFUg-1) were added to a HBR, with operational volume of 10,4L, fed with synthetic wastewater. The efficiency of the system was established in terms of removal of organic matter contained in the effluent for 13 days of continuous operation. Results. Polymers showing the high immobilization capacity were: BD (2,2x10(7) CFUg-1) and PUF (4,6x10(7) CFUg-1). The HBR, subjected to organic loading rate of 2.7 kg COD m-3d-1, showed operational stability for the treatments evaluated, reaching a removal of organic matter of 78% and 94%, by using BD and PUF as immobilization supports, respectively.

Reator em bateladas sequenciais de grânulos aeróbios: estudo da formação dos grânulos e do efeito da duração do ciclo na remoção de carbono, nitrogênio e fósforo de esgoto doméstico / Aerobic granular sludge sequencing batch reactor: study of granule formation and the cycle time effect in the carbon, nitrogen, and phosphorus removal from domestic wastewater

Neste trabalho estudou-se a formação de grânulos aeróbios em um reator em bateladas sequenciais alimentado com esgoto doméstico e avaliou-se o desempenho desse reator em relação à remoção de carbono, nitrogênio e fósforo utilizando ciclos operacionais de 3 e 4 h. Após 150 dias de operação, a biomassa do reator era constituída predominantemente por grânulos maduros e compactos, com concentração de sólidos suspensos em torno de 1,5 g.L-1. O reator apresentou elevada capacidade de remoção de carbono, nitrogênio e fósforo, principalmente quando operado em sucessivos ciclos de 4 h, atingindo uma eficiência média de remoção de demanda química de oxigênio solúvel de 82±5%, de NH4+-N de 69±19% e de PO43--P de 30±10%.

In this work, the formation of aerobic granules in a sequencing batch reactor fed with domestic wastewater was studied and the reactor's performance, in terms of carbon, nitrogen, and phosphorus removal, during operational cycles of 3 and 4 h, was evaluated. After 150 days of operation, the reactor's biomass predominantly consisted of compact mature granules, with a suspended solids concentration around 1.5 g.L-1. The reactor presented a high capacity for removing carbon, nitrogen, and phosphorus, mainly when operated in successive cycles of 4 h. Average removal efficiencies of 82±5% for soluble chemical oxygen demand, 69±19% for NH4+-N, and 30±10% for PO43--P were obtained.

Constructed wetlands for domestic wastewater treatment in a Mediterranean climate region in Chile

Background: Constructed wetlands are a promising, cheap and effective wastewater treatment in small communities. The studies on these systems have been reported mainly from cold, tropical or subtropical climate regions. In this work we constructed a pilot plant with six horizontal subsurface flow constructed wetlands (HSSF CWs) with a surface area of 2 m² and a depth of 0.6 m each, planted with Typha latifolia or Scirpus sp., and filled with gravel (G) or fine gravel (FG) of 2.8 and 1.2 cm of diameter respectively, continuously fed with raw domestic wastewater. This experimental setup was evaluated over 280 days for the removal of organic matter and nutrients in a Mediterranean climate, near Valparaíso, Chile. The removal of total COD, NH4+-N and PO4-3-P was calculated, in order to assess by analysis of variance the effect of initial pollutants concentration, air temperature (season) and plant/support combination on the wetlands performance. Results: The Scirpus/FG combination showed the highest average removal of total COD of about 59%, and Typha/FG shows the highest removal of NH4+-N and PO4-3-P (49 and 32%, respectively). Furthermore, the removal of organic matter was independent of influent concentration, while mildly dependent of the season, unlike nutrients removal that was dependent on these two parameters. Media, plant and the plant/media combination influenced positively organic matter, ammonia and phosphorous removal, respectively. Conclusions: Overall, the results demonstrate the potential of wetlands in treatment of wastewater in Mediterranean regions and show how these can help to improve the quality of water in domestic zones without high-throughput technologies.

Sequential Application of Plastic Media- Trickling Filter and Sand Filter for Domestic Wastewater Treatment at Low Temperature Condition.

Present research was aimed towards designing and construction of efficient plastic media-trickling filter (TF) for the treatment of domestic wastewater. The hydraulic flow rate through the TF was maintained at 80±2 ml/min at a temperature range of 5-15ºC by selecting treatment time of 12, 24, 36 and 48 hrs. Parameters like COD, BOD5, TSS, turbidity, NO3, NO2, SO4, PO4 and pathogenic indicator microbes were monitored after treatment of 12, 24, 36 and 48 hrs. The efficiency of the TF was improved with increase of time from 12 to 48 hrs. Maximum efficiency of TF was observed after 48 hrs treatment viz. 93.45, 93, 86.25, 57.8, 63.15, 25, 32.43, 99.95 and 86.3% reduction from the zero time value for BOD5, COD, TSS, PO4, SO4, NO3, NO2, turbidity and fecal coliforms respectively. Finally 48 hrs treated sample was passed through sand filter (SF) for further final polishing and approximately, 95.72, 95, 100, 73.5, 65.8, 58.3, 37.83, 100 and 91.5% reduction in BOD5, COD, TSS, PO4, SO4, NO3, NO2, turbidity and fecal coliforms was observed. This study showed that plastic media-trickling filter along with sand filter is a promising technology for wastewater treatment and can be scaled up for small communities in the developing countries.

Operação de filtros biológicos percoladores pós-reatores UASB sem a etapa de decantação secundária / Operation of trickling filters post-UASB reactors without the secondary sedimentation stage

A pesquisa teve por objetivo avaliar filtros biológicos percoladores (FBP) pós-reatores UASB operando sem a etapa de decantação secundária, em termos da remoção da demanda bioquímica e química de oxigênio (DBO e DQO) e sólidos suspensos totais (SST). O aparato experimental consistia em um reator UASB que alimentava quatro FBP em paralelo, preenchidos com diferentes materiais suporte. O reator UASB operou em regime hidráulico permanente, e três condições operacionais foram impostas aos FBP durante o período experimental. Em geral, os sistemas UASB/FBP foram capazes de promover o atendimento aos padrões de lançamento. Em condições de baixas cargas orgânicas volumétricas (COV), o uso de materiais de enchimento de maior área superficial específica não proporcionou ganhos expressivos em termos de desempenho. Contudo, o uso de meio suporte baseado em espumas de poliuretano propiciou melhoria significativa na qualidade do efluente final. O uso de sistemas UASB/FBP sem decantadores secundários parece ser uma promissora alternativa para a simplificação operacional da tecnologia, e uma importante estratégia para o tratamento de efluentes domésticos em países em desenvolvimento. No entanto, o sucesso do emprego desta tecnologia fica condicionado ao correto gerenciamento do lodo anaeróbio do reator UASB, a fim de que sejam evitadas sobrecargas nos FBP.

The research aimed at evaluating the operation of trickling filters (TF) post-UASB reactors without the secondary sedimentation stage, in terms of biochemical and chemical oxygen demand (BOD and COD) and total suspended solids (TSS) removal. The experimental apparatus consisted of one UASB reactor followed by four TF in parallel, each one filled with a different packing media. The UASB reactor was operated at a permanent hydraulic regime, while three operational conditions were imposed to the TF during the experimental period. In general, the UASB/TF systems were able to comply with the discharge standards. At low organic loading rates (OLR), no improvements in terms of organic matter removal, with the use of higher surface area packing media were observed. However, the use of a sponge-based packing media provided significant improvements on final effluent quality. The use of UASB/TF systems without secondary sedimentation can constitute an attractive alternative in terms of operational simplification of this technology, and an important strategy for domestic wastewater treatment in developing countries. However, the success of this technology is strictly connected to the correct anaerobic sludge management of the UASB reactor, in order to avoid overloads on the TF.

Irrigation with domestic wastewater: Responses on growth and yield of ladyfinger Abelmoschus esculentus and on soil nutrients.

Domestic wastewater is generated continuously and in large quantities. It can serve as an alternative water nutrient source for irrigation. In the present study Abelmoschus esculentus L. (Ladyfinger) was irrigated using untreated wastewater (T1), treated wastewater (T2) and rainwater (T3) in pot experiments. The effect was seen on nutrient fortication, growth and yield of the plant and the nutrient status of the soil. Additionally the build up of Cr, Cu and Zn from the irrigation water were anlayzed in different parts of the plant biomass and in the soil. The sapling survival rate was found to be 87% in T1 followed by T2 and T3. Root shoot ratio under different treatments was found in the order T3 (0.46) >T2 (0.35) >T1 (0.31). The chlorophyll a, b and carotene content in the leaves (mg g-1) was found to be 6.3, 0.5, 0.9 under T1, 4.8, 0.4, 0.8 under T2 and 3.2, 0.3, 0.5 under T3 respectively and all the three varied in the order T1>T2>T3. The same trend was found in case of total dry matter (g) T1 (6.3) >T2 (3.7) >T3 (2.3) at p<0.05. There was a considerable increase in nutrients in the soil under T1 and T2 as compared to T3 after final harvest. The organic matter (%), NO3 -N and PO4 3- (mg kg-1) content post harvest soil was found to be 3.4, 71, 90 under T1 and 2.9, 52, 63 under T2 respectively. Also, there was an increase in cations Na, K, Ca and Mg in the soil irrigated with T1 and T2 after the final harvest. Thus irrigation with wastewater generally increased soil fertility. Only a small percentage of the heavy metal was bioaccumulated by the plant parts from the irrigation water. There was hardly any metal accumulation in fruits. Bulk of the metal ions remained in the soil.

Tratamento combinado de lixiviado de aterros de resíduos sólidos urbanos e esgoto doméstico como alternativa para a solução de um grave problema ambiental e de saúde pública - revisão bibliográfica. / Co-treatment of municipal solid waste landfill leachate and domestic wastewater as an alternative solution to a serious environmental and public health problem - a literature review.

A disposição de lixiviados de aterros de resíduos sólidos urbanos é um grande problema de saúde ambiental, com impactos sobre a saúde das populações que vivem em áreas circunvizinhas, devido às características poluentes deste lixiviado. Uma opção é coletar e direcionar o lixiviado para estações de tratamento de esgotos, nas quais podem ser tratados conjuntamente com o esgoto doméstico. A viabilidade dessa opção depende da existência de rede coletora de esgotos próxima ao aterro e da capacidade da estação de tratamento em assimilar as cargas, sobretudo orgânica e nitrogenada, advindas do lixiviado. Este trabalho apresenta uma revisão bibliográfica sobre o tratamento combinado de lixiviado e esgoto doméstico. Os estudos realizados mostram que a quantidade limite de lixiviado a ser recebida em estações de tratamento, sem comprometer a qualidade do efluente final, não é fixa, dada a grande variabilidade da composição dos lixiviados. Entretanto, a maioria dos estudos não apresenta variações significativas de qualidade para efluentes do tratamento combinado com até 2% de volume de lixiviado.

The disposal of municipal solid waste landfill leachates is a major environmental health problem, with impacts on the health of people living in surrounding areas due to the characteristics of leachate pollutants. One option is to collect and direct the leachate to sewage treatment plants, where it can be co-treated with domestic sewage. The viability of this option depends on the existence of sewerage near the landfill and the treatment plant capacity to absorb the loads, especially organic and nitrogen, stemming from leachate. This paper presents a literature review on combined treatment of leachate and domestic sewage. Studies show that the quantity limit of leachate to be received on treatment plants, without compromising the quality of the final effluent, is not fixed, given the great variability in the composition of leachate. However, most studies present no significant variations in quality for effluent treatment combined with up to 2% of the volume of leachate.

Avaliação de aspectos hidraúlicos e hidrológicos de sistemas alagados construídos de fluxo subsuperficial / Evaluating hydrological and hydraulic aspects in subsurface-flow constructed wetland systems

Este trabalho teve-se como objetivo avaliar os aspectos hidráulicos e hidrológicos de quatro sistemas alagados construídos (SACs), cultivados com taboa (Typha sp.) e utilizados no tratamento de esgoto doméstico pré-decantado em tanque séptico. O sistema foi alimentado com uma taxa de aplicação hidráulica (q) constante de 60, 47, 23 e 35 litro m-2 d-1, respectivamente, nos SACs 1, 2, 3 e 4, tendo recebido monitoramento e medição da condutividade hidráulica e evapotranspiração no sistema. Foram realizados balanços hídricos mensais, durante um período de seis meses. Os resultados evidenciaram que: a condutividade hidráulica no meio suporte é reduzida com o tempo de funcionamento do sistema; e o sistema de tratamento apresentou evapotranspiração média de 9,3 mm d-1, resultando num coeficiente da cultura (Kc) da taboa com variação de 2,22 a 4,58.

This work was conducted to evaluate both hydrological and hydraulic aspects in four constructed wetland systems (SACs), that were cropped with Typha sp. and used in the treatment of the domestic wastewater presettled in septic tank. The system was fed a constant water application ratio (q) of 60, 47, 23 and 35 liter m-2 d-1 in SACs 1, 2, 3 and 4, respectively, besides being monitored. The hydraulic conductivity and evapotranspiration were also measured. Water balances were monthly accomplished during six-months period. The results evidenced the hydraulic conductivity in the supportive medium to be reduced during the operating time of the system, as well as the treatment system showed an average evapotranspiration of 9.3mm d-1, as resulting into a cropping coefficient (Kc) of the Typha sp. ranging from 2.22 to 4.58.