TRATAMENTO, REUTILIZAÇÃO E RECICLAGEM DE ÁGUAS RESIDUAIS DA INDÚSTRIA DE CONSERVAS DE PEIXE

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Fish canning industry wastewater variability assessment using multivariate statistical methods

Publication . Cristovão, Raquel; Pinto, Victor Miguel da Silva; Gonçalves, António; Martins, Ramiro; Loureiro, José M.; Boaventura, Rui

Usually, fish canning industrial wastewaters have a highly variable composition over time. For a good performance of treatment processes it is necessary to limit that variation. However, extended wastewater monitoring, including all relevant analytical parameters, is expensive. This work proposes an efficient approach to minimize the analytical determina-tions number without compromising the global characterization goal. This way, fish canning industry wastewaters variability was assessed and interpreted through multivariate statistical tools application to analytical data obtained from a monitoring program carried out in a fish canning industry of northern Portugal. 23 physicochemical parameters were determined in 20 samples collected on an 8 months period. The results achieved by correlation analysis, principal component analysis (PCA) and cluster analysis (CA) led to the main water pollution sources identification and to the minimization of physical and chemical parameters number to be analyzed in order to achieve a correct wastewater characterization, at minimum cost. The main pollution sources proved to be the brine and eviscerating step waters. Dissolved organic carbon (DOC), total suspended solids (TSS), conductivity, pH, Ca2+, F−and one of the parameters SO4 ,NO3 and PO4 were identified as important parameters that must be monitored in order to obtain an accurate characterization allowing to define themost appropriate wastewater treatment.

2016Journal article

Open access

Fish canning wastewater treatment by activated sludge: Application of factorial design optimization. Biological treatment by activated sludge of fish canning wastewater.

Publication . Cristovão, Raquel; Gonçalves, Cristiana; Botelho, Cidália; Martins, Ramiro; Loureiro, José M.; Boaventura, Rui

The optimization of hydraulic retention time (HRT) and initial organic matter concentration for dissolved organic carbon (DOC) abatement of wastewater from a fish canning industry of northern Portugal by activated sludge was investigated using response surface methodology (RSM). The two parameters were chosen since it was found that the treatment efficiency is mainly influenced by them. The experimental data on DOC r emoval were fitted into a quadratic polynomial model using factorial design and RSM. The optimum process conditions were determined by analyzing the response surface of a three-dimensional plot and by solving the regression model equation. The obtained results showed a HRT of 6.4. h and an initial DOC of 406.2. mg/L as the best treatment conditions. Under these conditions, the maximum predicted DOC removal was 88.0%, confirming the feasibility and the reliability of fish canning wastewater treatment by activated sludge for organic content removal.

2015Journal article

Open access

Assessing the influence of oil and grease and salt content on fish canning wastewater biodegradation through respirometric tests

Publication . Cristovão, Raquel; Pinto, Vera; Martins, Ramiro; Loureiro, José M.; Boaventura, Rui

Fish canning industry wastewaters have high organic matter, oil and grease and salt (NaCl) content, which make difficult a proper treatment before discharge. In this work, their treatment was evaluated via activated sludge aerobic biological process through respirometric tests. Inhibition was found to be significant for NaCl concentr ations higher than 17.5 g/L. On the other hand, the oil and grease content affects the wastewater biodegradability in the same way that the organic matter content expressed as chemical oxygen demand: the lower oil and grease and organic matter concentrations, the lower the percentage of wastewater biodegradability. As a final conclusion, the aerobic biological treatment process by activated sludge proved to be appropriate to treat fish canning industrial wastewaters, leading to high organic matter degradation rates (average value of 4900 mg O2 /g COD .d). Additionally, the experimental results achieved with the respirometric tests may be useful for the design of activated sludge plants to treat this type of wastewaters.

2016Journal article

Open access

Fish canning industry wastewater treatment for water reuse – a case study

Publication . Cristovão, Raquel; Botelho, Cidália; Martins, Ramiro; Loureiro, José M.; Boaventura, Rui

The valorization of wastewaters from the fish canning industry is of great concern, not only because of the high quantities generated, but also economic and environmental benefits may result from a proper treatment approach of the waste generated while reducing costs related to wastewater discharge. A limiting factor for reuse and recycling treated fish canning wastewater into an industrial plant and also for other uses is the high salt content, which persists even after conventional treatment. So, the reuse of fish canning industrial wastewater was assessed by combining conventional treatments, such as sedimentation, chemical coagulation-flocculation and aerobic biological degradation (activated sludge process) followed by a polishing step by reverse osmosis (RO) and ultraviolet (UV) disinfection. In this investigation all these processes were optimized in order to remove essentially the effluent suspended particles (primary treatment), the organic matter content in the biological aerated reactor (secondary treatment) and, finally, the remaining salts and microorganisms (tertiary treatment). The overall removal efficiencies obtained were: 99.9% for dissolved organic carbon (DOC), 99.8% for oil and grease (O&G), 98.4% for total suspended solids (TSS), above 96% for anions and cations and 100% for heterotrophic bacteria expressed as colony-forming units (CFU). The final clarified effluent was found to have the quality requirements to be recycled or reused in the industrial plant, allowing the reduction of the effluent to be discharged, the water use and the costs of tap water for industrial use. As regards the energy and chemicals costs, to obtain a treated effluent to be reused in the process costs 0.85 V/m3. This value can be reduced by about 60% if the goal is only to meet the legislated standards for the effluent discharge into water bodies. Tap water for the industrial plant costs about 2.1 V/m3.

2015Journal article

Open access