Combined system for the treatment and reuse of urban wastewater: the efficiency of anaerobic reactors + hybrid constructed wetlands + ozonation

Abstract

The research developed a combined system in batch flow and in pilot scale for the treatment and reuse of urban effluents. The system was fed raw effluent from a university campus in Brazil and composed of four anaerobic reactors, three constructed wetlands (CWs) and an ozonation unit. The three sequential hybrid constructed wetlands were composed of a floating treatment wetland, an aerobic-anoxic baffled constructed wetland (CW) and a saturated vertifcal flow CW. Later, during the last trimester, weekly samples of the treated effluent were ozonated by bubbling with an application rate of 240 mg.h-1 O3. The system presented high removal rates efficiencies in terms of carbonaceous organic matter (78.9%), nitrogen (91.0%), color (96.7%) and turbidity (99.1%). In addition, it worked well for disinfection and acute ecotoxicity, but P was only efficiently (75%) removed in the first 8 months, with removing efficiency declining after this period. Ozonation provided significant color removal and an increased pH. The combination of floating, alternated upflow and downflow and saturated vertical flows improved the treatment of wastewater. This was due to the presence of both aerobic and anaerobic zones, as well as the filter substrate, through an integrated system with simple construction and operation and increased lifespan.

Avaliação De Ciclo De Vida E Econômica De Sistema De Tratamento E Reuso De Efluentes Integrando Reatores Anaeróbios, Wetlands Construídos E Ozonização

“…Como exemplo de integração de WCs com POAs, pode ser citada a integração de uma unidade de ozonização (que em presença de coadjuvantes como a radiação UVC pode ser um POA), e que tem potencial para promover a remoção da cor da água, aspecto fundamental para o reúso da água (COLARES et al, 2019). Vários pesquisadores investigaram diferentes configurações de WCs, desde sistemas muito simples até a combinação de WCs com sistemas mais complexos e sofisticados, como WCs aerados artificialmente (WU et al, 2014), WCs e microalgas (DE SOUZA CELENTE et al, 2019). Trabalhos com estas combinações podem também ser exemplificados com WCs e ozonização (TRIPATHI e TRIPATHI 2011;HORN et al, 2014); e unidade de WC associada à desinfecção UV (ÁLVAREZ et al, 2017).…”

“…O sistema foi monitorado por 12 meses, com coleta e análise semanal de amostras. Mais informações sobre o projeto do sistema e as condições de operação podem ser encontradas em Colares et al (2019).…”

“…Todos os parâmetros apresentados na Tabela 2 foram considerados na ACV de operação do sistema. A metodologia aplicada (vida útil de 20 anos para o sistema) foisemelhante às conduzidas por Garfí et al (2017) e Flores et al (2019).Fonte: Adaptado a partirde Colares et al (2019).A biomassa seca e úmida de macrófitas foi estimada em 57,26 kg e 272,68 kg para o primeiro e terceiro WCs, respectivamente. O sistema foi capaz de atingir a desintoxicação total do efluente, em ensaios agudos realizados com o microcrustáceo Daphnia magna (STRAUS, 1820), antes mesmo da unidade de ozonização.…”

Innovative Wastewater Treatment Technologies — The INNOQUA Project

“…Wetland technology has been adapted to treat industrial sewage, storm water and domestic wastewater (Zhang et al, 2015). Treatment performance can be sufficient to produce effluents that can be reused for restricted irrigation in agriculture (Chandrakanth et al, 2016;Colares et al, 2019;Nivala et al, 2019;Rahi et al, 2020;Sehar et al, 2016) and a recent study of full-scale wetlands in Mexico reveals exceptional capacity of wetlands to deal with some types of emerging pollutants (Herrera-Cárdenas et al, 2016).…”

“…Phosphorus removal in constructed wetlands is a result of two principle mechanisms: plant uptake and harvesting (as examined by authors including He et al, 2018) media sorption/precipitation (as examined by authors including Colares et al, 2019). However, despite these parallel mechanisms, constructed wetlands have a relatively low efficiency in phosphorus removal (Kumar and Asolekar, 2016;Vasconcellos et al, 2019;Zhang et al, 2015), therefore to comply with national and international discharge standards, it is usually necessary to use a final polishing step such as chemical precipitation (Colares et al, 2019).…”