CHEMICAL CHARACTERISTICS OF SEWAGE SLUDGE PRODUCED IN BRAZIL

Abstract

This study aimed to determine the chemical characteristics of domestic sludge produced in Brazil. The samples were collected in beds of dry sewage treatment plant. The waste sludge LD-1 and LD-10 were typically anaerobic sludge sample and LD-6 was a mixed sludge, rich in ferric chloride. LD-1 and LD-6 showed a moisture content of 12.0 and 11.5%, respectively. The highest ash content was observed in the sample LD-six (46.2%). The lower concentration of organic matter was detected in LD-6 (40.6%), because it is rich in ferric chloride sludge. LD-10 had the highest carbon content (27.0%). The main metals found in sludge sample LD-1 were iron, zinc, manganese, lead, copper, nickel and chromium. The total iron showed the highest concentration (28,911 mg/kg). Nickel has the lowest of them (24 mg/kg). All metals determined in the sludge LD-1 had concentrations below the limits set for agricultural use by the Brazilian resolution. The main functional groups detected in the sludge, through FTIR, were alcohol, carboxylic acid, amides, amines, phenols, hydrocarbons and silicates. The sludge appear in their chemical composition, various substances such as nucleic acids, proteins, carbohydrates, lipids, humic substances and cellulose. These compounds have a very high potential energy to be treated as mere waste. This potential can be transformed from waste to raw material, in thermal processes of incineration and pyrolysis.

Key Words: chemical analysis, functional groups, heavy metals, minerals, sewage sludge.