Hybrid constructed wetlands as post-treatment of blackwater: An assessment of the removal of antibiotics.

New sanitation systems have been developed to treat, recover energy and nutrients, and permit reuse processes at the source of generation, minimizing water use and flow segregation. Thus, this study was carried out with the objective of evaluating the potential of hybrid constructed wetlands in the removal of organic matter, nutrients, pathogenic microorganisms, and 12 antibiotics from blackwater previously treated by an upflow anaerobic sludge blanket reactor. A hybrid system of constructed wetlands was used, comprised of a horizontal subsurface flow constructed wetland with a total volume of 0.60 m3 followed by a vertical subsurface flow constructed wetland with a total volume of 0.20 m3. Three different hydraulic retention times were comparatively tested (1.0, 2.0, and 3.0 days for the horizontal subsurface flow constructed wetland, and 1.1, 0.9, and 0.4 days for the vertical subsurface flow constructed wetland) in four distinct stages. The plant species used was Canna x generalis. The results from this study demonstrate the potential of constructed wetlands as a suitable technology for post-treatment of segregated domestic wastewater (anaerobically-digested blackwater). Efficient reduction of COD, BOD5, total nitrogen, and total phosphorus (74, 93, 50, and 61%, respectively) was achieved, with a hydraulic retention time of 3.0 and 1.1 days for horizontal and vertical subsurface flow constructed wetland, respectively (stage IV). The presence of ciprofloxacin was confirmed by chromatographic and mass spectrometric analysis in an average concentration of 442.6 ng.L-1 at the inflow of the horizontal subsurface flow constructed wetland, but was not observed at the outflow.

Systematic review of the last 20 years of research on decentralized domestic wastewater treatment in Brazil: state of the art and potentials.

A DEWATS (decentralized wastewater treatment system) is an alternative for expanding sanitation. In Brazil, DEWATS is acknowledged by law and is part of the National Sanitation Plan strategy for achieving the treatment of 85.6% of all the generated wastewater by 2033, improving the current treatment index of 49%. This review's aim is to identify DEWATS studies in Brazil and to verify their potential for narrowing the national wastewater treatment deficit. Hence, aspects such as cost, maintenance, and efficiency were assessed. The archival research method (ARM) was used to identify papers published in the last 20 years through the scientific databases of Scopus, Science Direct, and Web of Science. Data regarding the general characteristics of each study were collected and compared to Brazilian environmental regulation and sanitation status. The results showed the evaluation of different technologies such as DEWATS, highlighting their flexibility and potential use in 79% of Brazilian counties. However, although 81% of the studies conducted performance analysis, none covered the main parameters required by Brazilian law. Although legal gaps for DEWATS improvement and consolidation have been identified and the interest in studying DEWATS has been increasing in the last five years, many barriers to their widespread use remain.

Nutrient and pathogen removal from anaerobically treated black water by microalgae.

The demand for systems that efficiently and sustainably recover value-added compounds and materials from waste streams is a major challenge. The use of wastewater as a source for recovery of carbon and nutrients is an attractive and sustainable alternative. In this study, anaerobically treated black water was treated in photobioreactors (PBRs) inoculated with Chlorella sorokiniana, and the process was investigated in terms of phosphorus and nitrogen removal, biomass growth, and the removal of pathogens. The consumption of bicarbonate (alkalinity) and acetate (volatile fatty acids) as carbon sources by microalgae was investigated. The average nutrient removal achieved was 66% for N and 74% for P. A high consumption of alkalinity (83%) and volatile organic acids (76%) was observed, which suggests that these compounds were used as a source of carbon. The biomass production was 73 mg L-1 day-1, with a mean biomass of 0.7 g L-1 at the end of the batch treatment. At the end of the experiments, a log removal/inactivation of 0.51 log for total coliforms and 2.73 log for Escherichia coli (E. coli) was observed. The configuration used, a flat-panel PBR operated in batch mode without CO2 supplementation, is a cost-effective and environmentally sustainable method for recovering of nutrients and production of algal biomass.

Black water treatment by an upflow anaerobic sludge blanket (UASB) reactor: a pilot study.

Decentralized sanitary wastewater treatment has become a viable and sustainable alternative, especially for developing countries and small communities. Besides, effluents may present variations in chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total nitrogen values. This study describes the feasibility of using a pilot upflow anaerobic sludge blanket (UASB) reactor to treat wastewater with different organic loads (COD), using black water (BW) and sanitary wastewater, in addition to its potential for preserving nutrients for later recovery and/or reuse. The UASB reactor was operated continuously for 95 weeks, with a hydraulic retention time of 3 days. In Phase 1, the reactor treated simulated BW and achieved 77% CODtotal removal. In Phase 2, treating only sanitary wastewater, the CODtotal removal efficiency was 60%. Phase 3 treated simulated BW again, and CODtotal removal efficiency was somewhat higher than in Phase 1, reaching 81%. In Phase 3, the removal of pathogens was also evaluated: the efficiency was 1.96 log for Escherichia coli and 2.13 log for total coliforms. The UASB reactor was able to withstand large variations in the organic loading rate (0.09-1.49 kg COD m-3 d-1), in continuous operation mode, maintaining a stable organic matter removal.

Wastewater Chlorination for Reuse, an Alternative for Small Communities.

Reuse of wastewater is a practice that has been employed all over the world, mainly in agriculture, where the main aim is to reduce the demand for water and provide nutrients. However, these waters for reuse often have excessive amounts of pathogenic microorganisms, requiring a specific disinfection step even after being subjected to a purification process. Thus, this research aimed to evaluate the potential use of calcium hypochlorite and sodium hypochlorite as disinfectant agents for the sanitary effluent of the treatment system based on constructed wetlands for later reuse. Disinfection tests were carried out in batch, using three dosages of hypochlorite (5, 10 and 15 mg.L-1) and different contact. In all disinfection tests, inactivation of indicator microorganisms (total coliforms and E. coli) was considered effective for the two disinfectant agents adopted, satisfying the criteria for reuse according to the World Health Organization (WHO). There was no formation of trihalomethanes after disinfection tests.

The influence of light intensities and micropollutants on the removal of total coliforms and E. coli from wastewater in a flat-panel photobioreactor.

The presence of micropollutants and pathogens in sanitary wastewater and surface water is a growing concern that impacts public health, environmental balance and the maintenance of water supply services. To improve sanitary wastewater treatment, it is necessary to develop and improve sustainable technologies. Among the available options, microalgae-based systems stand out for their efficiency and generation of value-added byproducts. To study the impact of luminosity and the presence of micropollutants (13 selected) on the removal of E. coli and total coliforms from real anaerobically treated wastewater, a pilot flat-panel photobioreactor (50 L) was operated in batch mode in a tropical climate region. This is the first study to evaluate whether micropollutants interfere with coliform groups, considering a microalgae-based system and an experiment in a tropical climate region. E. coli had better removal (from 104 to 101 CFU 100 mL-1) than did total coliforms (from 104 to 103 CFU 100 mL-1). The removal of E. coli was more strongly linked to luminosity and temperature, while the removal of total coliforms was influenced by the presence of the selected micropollutants.

Biofertilizers from wastewater treatment as a potential source of mineral nutrients for growth of amaranth plants.

Exploring alternative fertilizers is crucial in agriculture due to the cost and environmental impact of inorganic options. This study investigated the potential of sewage-derived biofertilizers on the growth and physiology of Amaranthus cruentus plants. Various treatments were compared, including control treatments with inorganic fertilizer and treatments with biofertilizers composed of microalgae, biosolids and reclaimed water. The following traits were investigated: photosynthetic pigments, gas exchange, growth, and leaf nutrient concentrations. The results showed that the concentrations of N, P, Cu, Fe Zn and Na nutrients, in the dry microalgae and biosolids, were quite high for the needs of the plants. The wet microalgae presented high concentration of Cu, Fe and Zn nutrients while reclaimed water contained high concentration of N, K, Ca and S. Na and Zn nutrients increased in the leaf of plants treated with dry microalgae and biosolid, respectively. At the beginning of the flowering phase, total chlorophyll and carotenoids contents were lower for plants grown with wet microalgae while for plants grown with higher doses of biosolid or reclaimed water total chlorophyll was increased, and carotenoids were not affected. Lower photosynthetic pigments under wet microalgae resulted in lower photosynthetic rates. On the other hand, amendments with dry microalgae and biosolid increased photosynthetic rates with the biosolid being the most effective. Higher applications of biosolid, wet and dry microalgae produced a considerable increase in shoot biomass of amaranth, with the dry microalgae being the most effective. Additionally, reclaimed water obtained after tertiary treatment of sewage with microalgae and biosolids applied alone showed promising effects on plant growth. Overall, these findings suggest that organic fertilizers derived from sewage treatment have the potential to enhance plant growth and contribute to sustainable agricultural practices.

Tannin-based coagulant for harvesting microalgae cultivated in wastewater: Efficiency, floc morphology and products characterization.

Tannin-based coagulants (TBCs) have the potential to be used to harvest microalgae cultivated at wastewater treatment plants. Their use would address the circular economy associated with the production of low-toxicity biomass and supernatant. Studies in this field are still scarce, and substantial gaps exist in the definitions of the flocculation process parameters. In this context, the objective of this work was to evaluate TBC performance as a natural coagulant for harvesting microalgae biomass grown in sanitary effluent digested in an up flow biofilter, as well establishing a path to enable recovery and reuse of wastewater nutrients. Classical removal techniques combined with image analysis and light scattering-based equipment were used to evaluate the coagulant performance, recovery efficiency, floc strength, and floc recovery compared to aluminum sulfate (AS). The results showed that TBC was able to efficiently harvest algal biomass from the effluent, achieving color, turbidity, and optical density (OD) removal efficiencies greater than 90% with only 5 min of sedimentation. The optimal harvesting dosage was 100 mg·L-1 for TBC and 75 mg·L-1 for AS. TBC presented the advantage of harvesting biomass without changing the pH of the medium and was also able to present satisfactory removal of the analyzed parameters (color, turbidity and OD) at pH values of 5.0, 7.0, and 8.5. In addition, TBC produced stronger flocs than AS, showing a better ability to resist breakage upon sudden shear rate variations. TBC produced macronutrient-rich biomass and supernatant that was similar to that produced with AS.

Disinfection of anaerobic/aerobic sanitary effluent using ozone: Formaldehyde formation.

The scarcity of natural resources supports the perspective of reusing treated effluents, mainly in agriculture, where the reduction in the demand of drinking water and the provision of alternative sources for nutrients are important. However, the process of disinfection, essential to the protection of human health, generates deleterious by-products to both humans and the environment. This research aimed to evaluate the use of ozone as a disinfectant for wastewater treated by anaerobic/aerobic baffled reactor for later agricultural reuse. Disinfection tests were conducted by applying ozone, in batch, with applied dosages of 5, 8, and 10 mg O3 /L and contact time of 7 min. All the tests led to formaldehyde formation, therefore within the standard suggested by the World Health Organization. For the indicators total coliforms and Escherichia coli, the ozone was considered effective, satisfying the criteria for agricultural reuse according to the World Health Organization of a dosage of 8 mg O3 /L. PRACTITIONER POINTS: Proposal of decentralized system (anaerobic/aerobic baffled reactor + ozone disinfection) for effluent treatment for agricultural reuse. Formation of formaldehyde dependent on applied ozone dose. Demand of ozone consumed preferentially for the formation of by-products, with low removal of COD. High formaldehyde formation (high ozone demand) can impair the inactivation of pathogens. System promotes effluent that meets the standards established by the World Health Organization (WHO) for agricultural reuse.

Acompanhamento operacional e avaliação de uma estação compacta de tratamento de esgoto sanitário: reator UASB seguido de filtro aerado submerso / Operational monitoring and evaluation of a compact sanitary wastewater treatment plant: UASB reactor followed by submerged aerated filter

RESUMO Estações Compactas de Tratamento de Efluentes (ECTEs) são uma ótima alternativa para a implantação de sistemas descentralizados de esgoto doméstico que possam atender pequenas comunidades. No entanto, tais sistemas ainda são pouco utilizados e há pouca experiência em relação à sua operação. Diante de tal demanda, esta pesquisa visou avaliar a eficiência e realizar o acompanhamento operacional de uma ECTE composta por reator Upflow Anaerobic Sludge Blanket (UASB), seguido de filtro aerado submerso (FAS), que está localizada no município de Uru, em São Paulo, Brasil. Durante a pesquisa, o sistema mostrou-se uma alternativa viável de tratamento para pequenas comunidades, pois apresentou boa eficiência, com valores médios de remoção de demanda bioquímica de oxigênio (DBO5) e demanda química de oxigênio (DQO) de 91 e 85%, respectivamente. O monitoramento realizado durante a pesquisa também contribuiu para melhorias gerais no sistema.

ABSTRACT Compact Wastewater Treatment Plants (CWTPs) are a great alternative to implementing decentralized sewage systems that can serve small communities. However, such systems are still poorly used and there is little experience regarding their operation. Based on such demand, this research aimed to evaluate the efficiency and to conduct an operational monitoring of a CWTP composed by an Upflow Anaerobic Sludge Blanket (UASB) reactor, followed by Submerged Aerated Filter (SAF), in the city of Uru, São Paulo, Brazil. During the research, the system proved to be a viable alternative for small communities, because it showed good efficiency, with average removal values of biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) of 91 and 85%, respectively. The monitoring carried out during the research also contributed to general improvements in the system.

Tratamento de esgoto sanitário de baixa carga utilizando reator compartimentado anaeróbio/aeróbio em escala piloto / Treatment of low-strength sanitary sewage using an anaerobic/aerobic baffled reactor in pilot scale

RESUMO O objetivo principal da pesquisa foi avaliar o potencial de tratamento de esgoto sanitário de baixa carga orgânica em reator compartimentado anaeróbio/aeróbio (RCAA) em escala piloto. O reator, mantido em temperatura ambiente (27ºC a 30ºC), foi implantado no campus da Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP) (Bauru, SP, Brasil) e tratou esgoto sanitário com carga orgânica entre 0,06 e 0,61 kg DQO.d-1. O RCAA é composto de quatro câmaras fisicamente separadas, sendo as três primeiras anaeróbias e a quarta aeróbia, seguidas por decantador laminar. O monitoramento foi realizado durante o período de 203 dias para tempos de detenção hidráulica total (TDH) de 33, 22, 16,5 e 8,25 horas. Durante o período experimental, verificou-se remoção média de matéria orgânica, em termos de demanda química de oxigênio total (DQOTotal), de 71 a 82% no sistema completo, com valores elevados de remoção na fase anaeróbia entre 62 e 71%. Em termos de sólidos em suspensão totais (SST), o reator apresentou remoções médias em torno de 90%. Os resultados obtidos nesta pesquisa permitiram um avanço no conhecimento operacional de uma alternativa biotecnológica de baixo custo, com o propósito de diminuir o impacto causado pela geração de esgotos de pequenas comunidades urbanas e rurais que ainda não contam com sistema de tratamento, e ainda possibilitar o reúso do efluente tratado.

ABSTRACT The research's main goal was to evaluate the treatment potential of low-strength sanitary sewage in an anaerobic/aerobic baffled reactor (AABR) at pilot-scale. The reactor, maintained at room temperature (27ºC to 30ºC), was deployed at Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP), campus Bauru (SP, Brazil), and treated sanitary sewage with organic charge between 0.06 and 0.61 kgCOD.d-1. The AABR was composed by four chambers, physically separated, being the first three chambers anaerobic and the forth chamber aerobic, followed by a settling tank. The monitoration was done during 203 days for the hydraulic retention times (HRT) of 33, 22, 16.5 and 8.25 hours. During the experimental period, it was verified in the whole system a chemical oxygen demand (COD) removal between 71 and 82%, with high removal rates in the anaerobic phase between 62 and 71%. In terms of total suspended solids (TSS), the reactor reached average removal around 90%. The progress reached with this research allowed to present a low cost biotechnological alternative, with the propose of solving the sewage demand derived from small urban and rural communities, and also making possible the reuse of the treated effluent.

Desinfecção de efluente anaeróbio com o uso de ozônio/cloro / Anaerobic effluent disinfection using ozone/chlorine

O principal objetivo desta pesquisa foi estudar o processo de oxidação, a eficiência da inativação de coliformes e a formação de subprodutos da ozonização, associado com a desinfecção de efluente sanitário anaeróbio proveniente de um reator UASB. Tal evento foi realizado por meio da aplicação das dosagens de ozônio de 5,0 mg.O3.L-1+ 10 mg.Cl2.L-1 (ensaio 1); 8,0 mg.O3.L-1+ 20 mg.Cl2.L-1 (ensaio 2) e 10,0 mg.O3.L-1+ 30 mg.Cl2.L-1 (ensaio 3). Neste trabalho, utilizou-se efluente da Estação de Tratamento de Esgoto da Universidade de São Paulo, no Brasil. As reduções médias totais da demanda química de oxigênio para os efluentes ozonizados/clorados foram de 9, 32 e 37% para os ensaios 1, 2 e 3, respectivamente. A inativação dos coliformes totais variou de >5,7 até 6,4 log10 e >5,8 até >6,0 log10para Escherichia coli. A formação de aldeídos não sofreu mudanças significativas (p=0,05) para as dosagens e os tempos de contato aplicados após os ensaios de ozonização/cloração.

The main purpose of this research was to study the oxidation process, the coliform inactivation effectiveness, and the formation of ozone disinfection byproducts, which were associated with disinfection of the anaerobic sanitary wastewater effluent from a UASB reactor. Such event was performed with ozone applied at doses of 5.0 mg.O3.L-1+ 10 mg.Cl2.L-1 (essay 1); 8.0 mg.O3.L-1+ 20 mg.Cl2.L-1 (essay 2), and 10.0 mg.O3.L-1+ 30 mg.Cl2.L-1 (essay 3). The wastewater used in this research was generated at the Wastewater Treatment Plant of Universidade de São Paulo, in Brazil. The total mean decreases of the chemical oxygen demand for ozonized/chlorinated effluents were 9, 32 and 37% for assays 1, 2 and 3 respectively. The total coliform inactivation varied from >5,7 to 6,4 log10 and >5.8 to >6.0 log10 for Escherichia coli. The formation of aldehydes did not suffer any significant changes (p=0.05) for dosages and contact times applied after ozonation/chlorination assays.

Resíduos sólidos no Brasil: contexto, lacunas e tendências / Solid waste in Brazil: context, gaps and trends

RESUMO O tema resíduos sólidos está em evidência na sociedade moderna, fato observado pela recente implantação da diretiva europeia, e no Brasil, com a criação da Política Nacional de Resíduos Sólidos. Entender o impacto dessa política na produção científica nacional é essencial para traçar novos rumos e tendências de pesquisa. Por meio de um estudo bibliométrico e cientométrico, esta pesquisa traçou o contexto nacional e global dos últimos 20 anos e encontrou áreas em que as pesquisas avançaram, como em resíduos sólidos urbanos, e lacunas essenciais para desenvolver mais o estado-da-arte nacional, como resíduos sólidos do transporte. Assim, os resultados encontrados fazem deste estudo uma ferramenta plausível como justificativa para novas pesquisas no tema.

ABSTRACT The theme of solid waste is in high evidence today, a fact noted by the recent implementation of the European directive, and in Brazil, by the National Solid Waste Policy. Understanding the impact of this policy on the national scientific production is essential to plan new directions and research trends. Through a bibliometric and scientometric studied, this research analyzed the national and global context of the last 20 years and found areas in which research progressed, as municipal solid waste, and essentials gaps to develop more the national state-of-the-art, as solid waste of transport. So, the results of this study are a plausible tool to justify for further research on this topic.