No abstract

The aim of this work was to evaluate the groundwater quality in the surrounding area of Visconde do Rio Branco landfill in Minas Gerais State. Between September 2010 to October 2011 the parameters pH, temperature, dissolved oxygen, electrical conductivity, E. coli, total coliforms, Al, Cd, Cu, Pb, Cr, Fe, Mn, Hg, and Zn were monitored in the leachate and in the wells, and besides those mentioned, biological oxygen demand and chemical oxygen demand were monitored in the streams present in the area of study. High levels of Mn, Fe, Al, Hg and microbiologic contamination were observed, which were more evident during rainy periods. Possible unconformities origins may be problems with leachate drainage, in ponds and landfill sealing system and in the coverage of the cells. There should be more control in the sealing and closure of the cells, as with the construction and maintenance of the drainage system ensuring all the leachate produced is sent to the treatment ponds.

The aim of the present work was to evaluate the relationship between the hydraulic retention time power parameter (n) of the modified first-order kinetic mathematical model (MFOKM) with the hydraulic dispersion number (d) and the organic matter degradability, obtained from the ratio of chemical and biochemical oxygen demands (COD/BOD) along the length of horizontal subsurface flow constructed wetlands (HSSF-CWs). For this purpose, unplanted HSSF-CWs prototypes of equal volumes and length/width ratios (L W-1) of 1.0, 4.0 and 7.3 were used. All HSSF-CWs were filled with gravel # 0 and received sanitary sewage (SW) during a period of 90 days, in which the BOD and COD, in the total and soluble forms, were monitored in the influent and effluents from the system. These units were subject to tracer tests, before and after the HSSF-CWs received the SW, to obtain d. The MFOKM was adjusted to the COD and BOD experimental data. In all cases, an inverse relation was observed between n and the parameters d or with the organic matter decay rate obtained in the initial part of the HSSF-CWs.

RESUMO No presente trabalho, teve-se por objetivo avaliar a influência da proporção geométrica e o tempo de operação na hidrodinâmica do sistema. Para isso, três sistemas alagados construídos de escoamento horizontal subsuperficial (SACs-EHSS) de diferentes razões comprimento:largura (L/B) foram caracterizados no que se refere ao comportamento hidrodinâmico, no início e após três meses de sua operação, durante o tratamento de esgoto sanitário. O comportamento hidrodinâmico foi avaliado por meio da técnica estímulo-resposta, com a injeção de traçador de cloreto de lítio (LiCl), na forma de pulso, e da construção da curva de distribuição dos tempos de residência (DTR), a partir da qual foram extraídos parâmetros que permitiram a análise hidrodinâmica dos sistemas. Verificou-se que todos os SACs-EHSS apresentaram comportamento hidrodinâmico do tipo disperso, embora tenha sido observada correlação inversa entre L/B e o número de dispersão (d) no sistema. O tempo de operação desses sistemas também proporcionou pequena redução no d, em todos os SACs-EHSS.