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Liquid effluent treatment resorting to microalgae cultivation

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Resumo:Bioreactors from raceway category for microalgae production installed in domestic wastewater treatment facility and in fertilizers industrial plant were followed for approximately 11 months. Microalgae natural growth, mainly Scenedesmus obliquus and Scenedesmus quadricauda, was determined to evaluate their participation in domestic wastewater treatment and effluent from fertilizer plant. At WWTF, two raceways were installed, respectively after primary treatment and secondary treatment. At FIP, the installation of one raceway bioreactor had as main goal microalgae development, aiming nutrient removal from the effluent with potential reduction costs associated to the treatment. Microalgae growth evaluation in raceways was accomplished through determination of biomass dry weight from 107 samples. To evaluate microalgae activity, routine analysis were made for nitrate determination and external laboratories analysis for nutrient content determination (total nitrogen, ammonia, Kjeldahl nitrogen and total phosphorus). The obtained results from analysis performed by external laboratories demonstrated that collected sample from secondary treatment raceway presented 95 % ammonia removal, 39 % Kjeldahl nitrogen and 73 % total nitrogen. Only ammonia concentration of 3.36 mg/ L was under discharged limit value of 10 mg/ L. To evaluate effluent quality after microalgae activity biochemical oxygen demand and chemical oxygen demand were also evaluated. However, only one sample from the different systems were evaluated and, therefore, they cannot be considered representative. One of the following steps after effluent treatment is biomass recovery. It was necessary to reach their dehydration using flocculation processes. Although the results, this approach was not optimized unlike the harvest performed using centrifuge where 76% yield was achieved.
Autores principais:Azevedo, Tiago Ferreira de
Assunto:Scenedesmus Nutrient recovery Raceway Secondary treatment Tertiary treatment Recuperação de nutrientes Tratamento secundário Tratamento terciário
Ano:2019
País:Portugal
Tipo de documento:dissertação de mestrado
Tipo de acesso:acesso aberto
Instituição associada:Universidade do Minho
Idioma:inglês
Origem:RepositóriUM - Universidade do Minho

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