AVALIAÇÃO DO PROCESSO DE CO-COMPOSTAGEM DE LODO DE TANQUE SÉPTICO UNIFAMILIAR E RESÍDUOS SÓLIDOS ORGÂNICOS

Abstract

This study had the object of evaluating the influence of the frequency of aeration and the quantity of structural material in the process of co-composting of sludge from house septic tanks with residual organic solids. The research was carried out at the Experimental Station for the Biological Treatment of Sewage (EXTRABES), in the city Campina Grande, Paraiba during the period from August 2008 to July 2009. To mount the experimental system of co-composting sludge was collected from the house septic tanks in the district of Malhada da Roça, in the small town of São João do Cariri, situated in the semi-arid region of the state of Paraiba. The residual organic solids were collected from the Paraiba Company for Food and Agricultural Services (EMPASA), Campina Grande, PB. The experimental system comprised a new treatment of co-composting of sludge from house septic tanks with residual organic solids using a process of turning over, with a frequency of 1, 2 and 3 times per week with proportions of porous material of 4 and 8%. The monitoring period was for 112 days and weekly samples were collected for physic-chemical analysis and parasite counts. The turning frequency did not have a significant effect on the transformation of total volatile solids during the treatment period. The quantity of added structural material directly influenced the efficiency of the transformation of dry mass which was inversely proportional to the percentage of structural material added. The process of co-composting showed efficient removal of helminthes eggs. The compost produced met the legal requirements in relation to the quantities of macronutrients. The efficiency of the co-composting system showed two distinct phases: namely rapid during the first 35 days and a slow subsequent phase. The kinetic constants for biodegradation were determined from adjusted exponential equations, and showed higher values during the rapid phase and values approximately ten times lower during for the slow phase.