Influência da taxa de recirculação de lixiviado na degradação de resíduos sólidos urbanos e produção de biogás

Abstract

The growing consumerism observed in the current society is closely related to the increase of solid waste production in the urban centers, causing to a concern about management and proper disposal. Landfills are a method used for final disposal of solid waste by specialized construction and operation techniques. The leachate recirculation in landfills accelerates the degradation process of organic matter and leachate treatment. This research aimed to evaluate the influence of leachate recirculation rates on the acceleration of municipal solid waste anaerobic digestion, using anaerobic reactors simulated landfill cells. The reactors were made from high density polyethylene containers (HDPE), with 49 cm height, 35 cm diameter and a volume of 47 L, including systems for rainfall simulation, leachate collection and recirculation and measuring the biogas production. The reactors were fulfilled with standard municipal solid waste with the organic fraction obtained at the University’s cafeteria. The treatments applied as follows: 100% generated leachate recirculation (R1), 50% generated leachate recirculation (R2) and no recirculation (R3). The rainfall simulation was made based upon historical Londrina’s rainfall data, being held in days interspersed with the leachate recirculation. The organic fraction was monitored, occurring before waste insertion in the reactors and at the end of the experiment. The parameters analyzed include pH, electric conductivity, total solids, volatile solids, total organic carbon, total nitrogen visual aspects of waste. The control of leachate was done on a weekly basis. The parameters analyzed here were pH, electric conductivity, COD, volatile organic acids, ammonia nitrogen, total solids and volatile solids. The quantification of biogas production was done using the volume displacement method, being measured every other day. The experiment period lasted 55 days. Recirculation promoted maintenance of high concentrations of constituents in R1 and R2 leachate. The occurrence of waste degradation in all of the reactors was observed, but more intense in R1 and R2. The recirculation created an increase in the leachate constituent concentrations in R1 and R2, while the absence of recirculation caused rinsing and dilution of leachate in R3. Recirculating 100% leachate produced in R1 may have influenced the inhibition of biogas production. The cumulative biogas production was statistically significantly higher in R2, pointing this treatment as beneficial to the acceleration of the anaerobic digestion of waste and biogas production.