This study assessed thermochemical pretreatment of microalgae harvested from a full-scale wastewater treatment pond prior to its anaerobic digestion using acid and alkaline chemical doses combined with thermal pretreatment at 80°C. Results indicated that alkaline and thermal pretreatment contributed mostly to glycoprotein and pectin solubilisation; whilst acid pretreatment solubilised mostly hemicellulose, with lower effectiveness for proteins. Regarding the anaerobic biodegradability, biochemical methane potential (BMP) tests showed that final methane yield was enhanced after almost all pretreatment conditions when compared to non-pretreated microalgae, with the highest increase for thermochemical pretreatment at the lowest dose (0.5%), i.e. 82% and 86% increase for alkaline and acid, respectively. At higher doses, salt toxicity was revealed by K(+) concentrations over 5000mg/L. All BMP data from pretreated biomass was successfully described by the modified Gompertz model and optimal condition (thermochemical 0.5% HCl) showed an increase in final methane yield and the process kinetics.
Avaliação da retenção de sólidos em inovadora configuração de reator UASB tratando esgoto doméstico
Solids retention in a new model of UASB reactor applied to domestic wastewater treatment
RESUMOA retenção de sólidos é um dos principais problemas de reatores UASB tratando esgoto doméstico. Apesar disso, estudos que proponham melhorar esse aspecto são escassos. Nesse sentido, o presente projeto avaliou o desempenho de uma configuração modificada de reator UASB com foco na redução da velocidade na passagem para o compartimento de decantação, que pode limitar o retorno do lodo ao fundo do reator. Para tanto, o reator foi projetado com duas passagens distintas, e seu desempenho foi comparado a um reator convencional. Os resultados indicaram a maior retenção de sólidos no reator modificado, que apresentou menores concentrações de SST no efluente (73-88 mg/L) comparado ao reator convencional (82-106 mg/L). Além disso, houve uma significativa maior produção de metano no reator modificado, devido ao maior tempo de permanência dos sólidos no reator (20-50%). Assim, o reator apresentou um bom potencial de aplicação sob esse aspecto.Palavras-chave: tratamento anaeróbio de esgoto, reator UASB, projeto do separador de fases, remoção de sólidos, retenção física de sólidos. (20-50%). Thus, the reactor showed a good potential application in this purpose.
ABSTRACT
Solids retention is one of main problems of UASB
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.