Septic tank sludge rate determination in the city of Merida, Yucatan

In the city of Merida, almost all the wastewaters are treated in septic tanks which are not operated properly. Therefore, a large proportion of organic content reaches the aquifer. In order to improve the efficiency of septic tanks, sludge accumulation rate has to be quantified. Equipment for the quantification of the existing volume of sludge in septic tanks were designed and constructed. A sludge accumulation rate of 19.07 l/capita per year was obtained from 2 sampling surveys. Sludge characteristics were determined and this is useful information for elaborating adequate treatment proposals.