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Estudo exploratório do uso de microalgas no afinamento da qualidade do efluente vinícola pré-tratado
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As microalgas têm sido utilizadas no tratamento de efluentes industriais, domésticos e da agroindústria, substituindo o uso de nutrientes comerciais. O presente estudo consistiu em desenvolver um tratamento de afinamento de águas residuais vinícolas usando culturas da microalga Chlorella minutissima. Fizeram-se ensaios exploratórios em “batch” de crescimento de microalgas em diferentes concentrações de efluente vinícola pré-tratado e em condições controladas de temperatura (25ºC), luz (2200 lux), agitação (120 rpm) e arejamento com caudal de ar de 2 L min-1 e com taxa de 30 min h-1. No final pretendeu-se validar a viabilidade do tratamento à escala piloto usando um pequeno tanque raceway (10 L). Durante os ensaios foram avaliados vários parâmetros físico-químicos no efluente tais como pH, oxigénio dissolvido (OD), condutividade elétrica do meio, carência química de oxigénio (CQO), polifenóis totais, azoto amoniacal (N-NH4+), azoto kjeldahl (Nk), fósforo solúvel, quantificação de sólidos sólidos totais (ST), sólidos voláteis totais (SVT), sólidos suspensos totais (SST), sólidos suspensos voláteis totais (SSVT) e biomassa produzida, com vista à reutilização da água e produção da microalga como biomassa útil.
Nos ensaios efetuados, onde se utilizou efluente arejado com pH acertado a 6,8 verificou-se que houve uma alta redução da CQO de aproximadamente 95%, o aumento de pH de 3,5 para 8 e OD de 1,0 para 6,0 mg/L, além da diminuição da quantidade de N-NH4+ e Nk em 20% e 37%, respetivamente. Relativamente ao crescimento microalgal, este foi influenciado pelo consórcio com as bactérias existentes na água residual vinícola. Entre o 4º e o 7º dia de cultivo, observou-se um pico na produção de biomassa que se deve sobretudo a fração bacteriana. Nesta fase as culturas apresentaram uma cor castanha. Na segunda parte do ensaio o crescimento foi mais lento e as culturas exibiram uma cor verde, o que demonstra a presença acentuada da microalga Chlorella minutissima. Os resultados demonstraram que foi possível efetuar um afinamento da qualidade do efluente vinícola com as microalgas.
Microalgae have been used in the treatment of industrial, domestic and agroindustrial wastewater. The present study consisted in developing a polishing treatment of winery wastewater using cultures of the microalgae Chlorella minutissima. Exploratory "batch" growth trials of microalgae were carried out in different concentrations of pretreated winery wastewater and under controlled conditions of temperature (25ºC), light (2200 lux), mixing (120 rpm) and aeration with air flow of 2 L min-1 and with rate of 30 min h-1. The main objective was to validate the feasibility of the treatment at pilot scale using a 10 L raceway tank, with the aim to reuse treated wastewater and producing microalgae as useful biomass. During the trials, several physicochemical parameters were monitored such as pH, dissolved oxygen (DO), electrical conductivity, chemical oxygen demand (COD), total polyphenols, ammoniacal nitrogen (N-NH4+), kjeldahl nitrogen (Nk), soluble phosphorus, quantification of total solids (TS), total volatile solids (TVS), total suspended solids (TSS) and total volatile suspended solids (TVSS) were determined on the winery wastewater as collected, after pretreatment and after polishing treatment with microalgae. and biomass produced. Results where aerated effluent with pH adjusted to 6,8 was used, showed approximately 95% reduction in COD, an increase of pH from 3.5 to 8 and of DO from 1.0 to 6.0 mg/L, as well as a decrease in the amount of N-NH4+ and Nk by 20% and 37%, respectively. The microalgae growth was influenced by the consortium with the bacteria of the wine wastewater. Between the 4th and 7th day of the cultures, a peak in biomass production was observed, which was mainly due to the bacterial fraction. At this stage the cultures showed a brown color. In the second part of the test, the growth was slower and the cultures presented a green color, which demonstrates the strong presence of the microalgae Chlorella minutissima. The results showed that it was possible to perform a quality improvement of the wine wastewater with microalgae.
Microalgae have been used in the treatment of industrial, domestic and agroindustrial wastewater. The present study consisted in developing a polishing treatment of winery wastewater using cultures of the microalgae Chlorella minutissima. Exploratory "batch" growth trials of microalgae were carried out in different concentrations of pretreated winery wastewater and under controlled conditions of temperature (25ºC), light (2200 lux), mixing (120 rpm) and aeration with air flow of 2 L min-1 and with rate of 30 min h-1. The main objective was to validate the feasibility of the treatment at pilot scale using a 10 L raceway tank, with the aim to reuse treated wastewater and producing microalgae as useful biomass. During the trials, several physicochemical parameters were monitored such as pH, dissolved oxygen (DO), electrical conductivity, chemical oxygen demand (COD), total polyphenols, ammoniacal nitrogen (N-NH4+), kjeldahl nitrogen (Nk), soluble phosphorus, quantification of total solids (TS), total volatile solids (TVS), total suspended solids (TSS) and total volatile suspended solids (TVSS) were determined on the winery wastewater as collected, after pretreatment and after polishing treatment with microalgae. and biomass produced. Results where aerated effluent with pH adjusted to 6,8 was used, showed approximately 95% reduction in COD, an increase of pH from 3.5 to 8 and of DO from 1.0 to 6.0 mg/L, as well as a decrease in the amount of N-NH4+ and Nk by 20% and 37%, respectively. The microalgae growth was influenced by the consortium with the bacteria of the wine wastewater. Between the 4th and 7th day of the cultures, a peak in biomass production was observed, which was mainly due to the bacterial fraction. At this stage the cultures showed a brown color. In the second part of the test, the growth was slower and the cultures presented a green color, which demonstrates the strong presence of the microalgae Chlorella minutissima. The results showed that it was possible to perform a quality improvement of the wine wastewater with microalgae.
Descrição
Mestrado em Engenharia do Ambiente. Universidade de Lisboa, Instituto Superior de Agronomia
Palavras-chave
águas residuais vinícolas Chlorella minutissima microalga remoção de nutrientes winery wastewater microalgae nutrient removal
Contexto Educativo
Citação
Nunci, A.M. Estudo exploratório do uso de microalgas no afinamento da qualidade do efluente vinícola pré-tratado. Lisboa: ISA-Universidade de Lisboa, 2023. Dissertação de Mestrado
Editora
Instituto Superior de Agronomia, Universidade de Lisboa