ABSTRACT
The objectives of the present study were to characterize and evaluate a pilot treatment unit (PTU) for dairy cattle wastewater (DCW) in relation to its efficiency in reducing the physicochemical and microbiological parameters and possible application of this fertilizer in organic production. A PTU was set up, composed of the following elements: a dung pit of 7.8 m3, already in place; a septic tank; a set of anaerobic biological filters comprising an upflow filter and a downward-flow filter filled with fragments PVC corrugated conduit; and two constructed wetland systems (CWSs) of horizontal subsurface flow in two parallel routes (Routes 1 and 2), controlled by means of a flow rate divider box. Route 1 passed through CWS 1 cultivated with cattail (Typha domingensis) and Route 2 passed through CWS 2 cultivated with vetiver grass (Chrysopogon zizanioides). To evaluate the treatment stages, biweekly investigations were carried out to collect effluent samples. The results of monitoring, in absolute values, were evaluated by means of the medians and variation coefficients and compared by means of Kruskal-Wallis non-parametric test followed by the Student Newman Keuls test. The treatment efficiencies of Routes 1 and 2 were calculated. The influence of vetiver on the removal of nutrients from the DCW was analyzed and the productivity estimate (t.ha-1) was performed. CWS 1 was not able to reduce the organic load indices, but it was able to retain fatty material and sodium. CWS 2 showed a reduction in nitrogenous forms and also for other nutrients, achieving the greatest removal of sodium and greatest decay of fecal contamination indicators, thermotolerant coliforms (56.13%), and E. coli (46.82%).
Subject(s)
Chrysopogon , Typhaceae , Animals , Cattle , Wastewater , Escherichia coli , Wetlands , Nitrogen , Waste Disposal, Fluid/methodsABSTRACT
RESUMO Parte dos resíduos coletados nos municípios brasileiros ainda são destinados de forma inadequada, resultando em transtornos à qualidade de vida e à saúde pública. Assim, a caracterização gravimétrica dos resíduos é um importante instrumento de gestão integrada, uma vez que permite conhecer quantitativamente as frações geradas. Nesse sentido, o presente estudo teve por objetivo analisar estatisticamente a composição gravimétrica dos resíduos sólidos domésticos de Juiz de Fora, Minas Gerais, em função das sete regiões urbanas do município e da renda domiciliar da população. Cerca de 140.500 toneladas de resíduos sólidos domésticos foram coletadas no município em 2015, representando uma geração per capita de 0,7 kg/hab./dia. Foram feitos testes estatísticos de hipóteses a 5% de significância em avaliações comparativas, além de testes de correlação para as frações majoritárias (orgânicos e recicláveis) e as respectivas rendas domiciliares. Os resultados indicaram que a fração de orgânicos corresponde a 43,81% dos resíduos gerados no município, 31,74% são passíveis de reciclagem, 14,36% são resíduos potencialmente contaminantes e 10,10% são rejeitos diversos. Observou-se que o resíduo gerado por famílias de alto poder aquisitivo tende a conter maiores percentuais de recicláveis, enquanto em famílias de menor poder aquisitivo os maiores percentuais tendem a ser de orgânicos. A grande incidência de orgânicos e recicláveis evidencia um potencial a ser explorado, apontando a necessidade de reavaliação da estrutura da coleta seletiva e possível instalação da usina de compostagem, mediante estudo de viabilidade técnica e econômica. Por fim, espera-se que o estudo auxilie o poder público local, norteando o planejamento e o dimensionamento de sistemas de coleta, tratamento e destinação de resíduos, além de projetos de educação ambiental, servindo de modelo para outras municipalidades.
ABSTRACT Much of the solid waste collected in Brazilian municipalities is still inappropriately destined, resulting in disorders related to quality of life and public health. Thus, the gravimetric characterization of household solid wastes is an important instrument of integrated management, since it quantitatively indicates the fractions generated. In this sense, the present study aims to analyse statistically the gravimetric composition of solid household waste from Juiz de Fora, Minas Gerais, Brazil, generated in 2015 regarding the seven urban regions of the city and the domestic income of the population. Statistical tests of hypothesis were carried out at 5% significance in comparative assessments, as well as correlation tests for organic and recyclable fractions and their respective domestic incomes. The results indicated that the organic fraction corresponds to 43.81% of the solid waste generated in the municipality, 31.74% is the recyclable fraction, 14.36% to potentially contaminant wastes and 10.10% of others. It was observed a trend of greater generation of recyclables in regions with higher socioeconomic status; on the other hand, regions with a predominance of families with lower incomes there was an increase in organic fraction. The high incidence of organic and recyclable materials indicates a potential to be explored, pointing out the need of re-evaluating the structure of the selective collection and the possible installation of a composting plant by a technical and economical feasibility study. Therefore, it is expected that the study supports the local public power, guiding the plan and design of solid waste collection, treatment and disposal systems, as well as environmental education projects and serving as a model for other municipalities.
