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Vitoria., Brazil

Furley T.H.,APLYSIA Solucoes Ambientais | Lombardi J.B.,APLYSIA Solucoes Ambientais | De Souza Gomes A.S.,APLYSIA Solucoes Ambientais
O Papel | Year: 2015

The effluents from pulp and paper mills comprise a wide variety of chemical compounds coming from different sectors of the plant, which can be toxic to the sewage treatment microorganisms and the living beings in the discharge receiving body. To reduce ecotoxicity, and to minimize impacts of pulp and paper effluents on the aquatic ecosystem, it is important identifying the sources that contribute to the overall ecotoxicity of the mill effluent, estimate the toxic load from each process stream, and manage them so as to reduce the impact on the effluents treatment station (ETE), lessening treatment costs and improving the overall quality of the treated effluent. This work brings together the results of APLYSIA experience in ecotoxicological characterization of twenty-five effluents from different sector of three Latin American pulp and paper mills, in addition to their effects on the ETE microorganisms and the quality of the final treated effluent. The balance sheet has shown that toxicity of the whole alkaline effluent, the acid bleaching and the contaminated condensate were the largest contributors to the overall toxicity of the evaluated effluent plants, reaching contribution of 395.166 UT m/day, 200.842 UT m3/day and 13.559.322 UT m3/day, respectively. These effluents increased toxicity of the untreated total effluent, impacted on bacterial and protozoan ETE flakes formation, decreased the BOD and COD removal efficiency, as well as augmented turbidity and solids and organic matter content in the treated final effluent.

Lombardi J.B.,APLYSIA Solucoes Ambientais | De Souza Gomes A.S.,APLYSIA Solucoes Ambientais | Furley T.H.,APLYSIA Solucoes Ambientais | Saldanha V.J.D.,CENIBRA Celulose Nipo Brasileira S.A | And 3 more authors.
O Papel | Year: 2015

Among typical problems in Waste Water Treatment plant, the main and most common is the loss of solids in treated effluent due to insufficient separation between liquid and biomass of the activated sludge during decanting. The presence of this effluent solids may be related to the formation of viscous bulking, also known as non-filamentous bulking. In this process, there is an excessive production of extracellular polymers by bacterial cells, which can give a gelatinous consistency to the biological sludge and cause a reduction in the rate of settling and compaction. During the microbiological monitoring of the wastewater treatment at pulp mill Celulose Nipo-Brasileira S.A. CENIBRA -, excess extracellular polymers was identified through biological sludge microscopic analysis, using the India ink method, which revealed large biological flake areas impermeable to the ink, indicating presence of extracellular material in the environment and inside the flake. Due to the presence of this extracellular material, losses were observed in the structure of the biological floc, which impaired sludge settling and was cause of flotation at the secondary clarifiers. As a result, there was an increase in concentration of the total suspended solids and settleable solids in the treated effluent. In addition, the sludge consistency at the thickener decreased during this period, showing reduction in sludge compactness. After microscopic sludge evaluation and identification of the microbiological problem, it was possible to define the causes for this phenomenon. Occurrences of viscous bulking were identified during months of May, June and July/2013, when concentration of dissolved oxygen in the aeration tanks persisted high, and residual nutrients in the treated effluent was low. In mid July/2013, when better aeration control was performed and with reduced oxygen concentration, it was possible to notice a significant decrease of extracellular materials and absence of bulking. During that period, better results were also perceived in nutrients concentration in the treated effluent from the WWT.

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