Assessment of Combined Treatment of Landfill Urban Solid Waste Leachate and Sewage Using Danio rerio and Daphnia similis

Abstract

The co-treatment from Morro do Céu landfill leachate with domestic sewage in the Icaraí STP was monitored with regard to the behavior of toxicity of its inflows and outflow. Leachate not exceeded 1.5% in volume in the plant. The acute ecotoxicological tests showed that, although leachate is far more harmful to D. rerio (LC50 approximately = 4) and D. similis (LC50 approximately = 5) than sewage (LC50 approximately = 62; LC50 approximately = 22), statistically the mixture of leachate with sewage did not result in a more toxic inflow (LC50 approximately = 57; LC50 approximately = 12) for treatment than raw sewage. After treatment, the outflow toxicity (LC50 approximately = 76; LC50 approximately = 16) complied with the environmental laws.

Evaluation of coagulation/flocculation process in the landfill leachate treatment at the Municipal Wastewater Treatment Plant

“…This result is in agreement with Mannarino et al (2010) that showed values of 2-4 units of toxicity for 0.37 to 1.22% of landfill leachate in sewage (the same parameters used in this work).…”

“…The authors obtained the following value ranges: -for raw sewage, pH: 6.7 -7.6; Turbidity: 11.0 -328.4 NTU; COD: 53-316 mg.L -1 ; TSS: 100-250 mg.L -1 and N-NH 3 :11-70 mg.L -1 ; for landfill leachate, pH: 7.5-8.5; Turbidity: 2.0-70.5 NTU; COD: 685-1913 mg.L -1 ; TSS: 40-473 mg.L -1 and N-NH 3 :522-1394 mg.L -1. -Except for the pH of sewage and landfill leachate, which showed similar value ranges for both studies, the study from Mannarino (2010) shows greater variation than this study, probably because the sampling had been done during a year and so the samples showed a large range of variation. -Table 3 shows results of COD and Turbidity in the minimum conditions (coagulant and polyelectrolyte dosage) that achieved the minimum removal COD (30 %).…”

“…These variations can be explained by weather changes, such as rainfall, since the collection point was the same for all samplings. Mannarino et al (2010) monitored the Icarai MWTP leachate from Morro do Céu during a year. The authors obtained the following value ranges: -for raw sewage, pH: 6.7 -7.6; Turbidity: 11.0 -328.4 NTU; COD: 53-316 mg.L -1 ; TSS: 100-250 mg.L -1 and N-NH 3 :11-70 mg.L -1 ; for landfill leachate, pH: 7.5-8.5; Turbidity: 2.0-70.5 NTU; COD: 685-1913 mg.L -1 ; TSS: 40-473 mg.L -1 and N-NH 3 :522-1394 mg.L -1.…”

“…*not performed Table 4 shows, in summary, the results achieved at the second step. Mannarino et al (2010) also monitored the inflow and outflow of Icaraí MWTP, which during the monitoring period received 0.37 to 1.22% of landfill leachate. In this period, according to the authors, the treatment efficiency of coagulation/flocculation (chemicals not reported) was on average 55.6% COD removal.…”

“…According to Mannarino et al (2010), combined treatment solves the problems found in treating leachate separately. From the operational perspective of the sewage treatment plants, consideration must be given to the difficulties the leachate might cause in the treatment process, to include an increase in toxicity of the treated effluent.…”