Efeito da adição de farinha de linhaça à dieta sobre a concentração de colesterol e ácidos graxos em camarões / The effect of feed added of linseed on cholesterol and fatty acids in shrimp

Avaliou-se a expressão de ácidos graxos, macronutrientes e colesterol de camarões-da-malásia alimentados com dieta adicionada de sementes de linhaça. Quinhentos camarões foram distribuídos em dois grupos e alimentados durante 90 dias com dietas contendo: 1) lipídeo proveniente de linhaça e 2) óleo de soja (controle). A concentração de proteína foi maior (Р<0,05) para o grupo-linhaça, 15,8±0,09%, em relação ao grupo-controle, 15,2±0,04%. O peso corporal também se apresentou maior no grupo-linhaça, 1,38±0,93g, em relação ao grupo-controle, 0,93±0,48g. O grupo-linhaça apresentou teor de colesterol de 120,8±23,9mg/100g e o grupo-controle, 130,2±13,9mg/100g, porém sem diferença estatística significativa. Em relação ao perfil lipídico, a suplementação da dieta com linhaça influenciou a incorporação do ácido oleico (C18:1, ω-9) e melhorou a relação ω-6/ω-3 na carne do camarão (Р<0,05). Concluiu-se que a adição de linhaça à ração promoveu importantes modificações na qualidade nutricional dos tecidos do camarão.

The aim of the present study was to analyze the chemical composition of shrimp fed with a diet added of linseed flour. Five hundred post larvae shrimp were divided into two groups: a linseed group fed with a diet based on casein complemented with linseed and a control group, fed a diet without linseed flour. The cholesterol content for the linseed group was 120.8±23.9 mg/100g while for the control group it was 130.2±13.9 mg/100g. However, the protein content of 15.8±0.09 % and the body weight of 1.38±0.93g for the linseed group were higher than for the control group. It was concluded that the addition of linseed to the diet seems to increase the protein, weight and oleic acid (C18:1, ω-9) in the shrimp tissue. The ratio of polyunsaturated fatty acids/saturated fatty acids and ω-6/ω-3 for the linseed group was more suitable than for the control group.

Electrochemical mineralization of anaerobically digested olive mill wastewater.

A novel approach was developed for the energetic valorisation and treatment of olive mill wastewater (OMW), combining anaerobic digestion and electrochemical oxidation. The electrochemical treatment was proposed as the final step to mineralize the remaining OMW fraction from the anaerobic reactor. The electrooxidation of anaerobically digested OMW was investigated over dimensionally stable anodes (DSAs). RuO(2) based anode was significantly more efficient than IrO(2)-type DSA, mainly for the COD removal. IrO(2) based anode promoted a selective oxidation of phenols and colour removal. For instance, after an electrolysis charge of 10.4 × 10(4) C L(-1), COD removals of 14 and 99%, phenols removals of 91 and 100% and colour removals of 85 and 100% were obtained for IrO(2) and RuO(2) DSAs-type, respectively. The electrochemical post-treatment was effectively performed without using a supporting electrolyte and in the presence of the solids that remained from the anaerobic process. The achievement of the required effluent quality for sewer systems disposal depends on the operating conditions of the anaerobic process. Consequently, special care must be taken with the chloride and nitrogen levels that may surpass the legal discharge limits. The electrochemical oxidation over RuO(2) based DSA is an appropriate second-step treatment for OMW disposal, after the recovery of its energetic potential.

Strategies for lipids and phenolics degradation in the anaerobic treatment of olive mill wastewater.

Strategies are proposed for the anaerobic treatment of lipid and phenolic-rich effluents, specifically the raw olive mill wastewater (OMW). Two reactors were operated under OMW influent concentrations from 5 to 48 g COD L(-1) and Hydraulic Retention Time between 10 and 5 days. An intermittent feeding was applied whenever the reactors showed a severe decay in the methane yield. This strategy improved the mineralization of oleate and palmitate, which were the main accumulated Long-Chain Fatty Acids (LCFA), and also promoted the removal of resilient phenolic compounds, reaching remarkable removal efficiencies of 60% and 81% for two parallel reactors at the end of a feed-less period. A maximum biogas production of 1.4m(3)m(-3)d(-1) at an Organic Loading Rate of 4.8 kg COD m(-3)d(-1) was obtained. Patterns of individual LCFA oxidation during the OMW anaerobic digestion are presented and discussed for the first time. The supplementation of a nitrogen source boosted immediately the methane yield from 21 and 18 to 76 and 93% in both reactors. The typical problems of sludge flotation and washout during the anaerobic treatment of this oily wastewater were overcome by biomass retention, according to the Inverted Anaerobic Sludge Blanket (IASB) reactor concepts. This work demonstrates that it is possible to avoid a previous detoxification step by implementing adequate operational strategies to the anaerobic treatment of OMW.

Anaerobic digestion challenge of raw olive mill wastewater.

Olive mill wastewater (OMW) was digested in its original composition (100% v/v) in an anaerobic hybrid. High concentrations (54-55 kg COD m(-3)), acid pH (5.0) and lack of alkalinity and nitrogen are some OMW adverse characteristics. Loads of 8 kg COD m(-3) d(-1) provided 3.7-3.8 m3 biogas m(-3) d(-1) (63-64% CH4) and 81-82% COD removal. An effluent with basic pH (8.1) and high alkalinity was obtained. A good performance was also observed with weekly load shocks (2.7-4.1, 8.4-10.4 kg COD m(-3) d(-1)) by introducing piggery effluent and OMW alternately. Biogas of 3.0-3.4 m3 m(-3) d(-1) (63-69% CH4) was reached. Developed biomass (350 days) was neither affected by raw OMW nor by organic shocks. Through the effluents complementarity concept, a stable process able of degrading the original OMW alone was obtained. Unlike what is referred, OMW is an energy resource through anaerobiosis without additional expenses to correct it or decrease its concentration/toxicity.

Electrooxidation as the anaerobic pre-treatment of fats: oleate conversion using RuO2 and IrO2 based anodes.

Electrochemical treatment of oleate using RuO2 and IrO2 type dimensionally stable anodes in alkaline medium was performed to develop a feasible anaerobic pre-treatment of fatty effluents. The results showed that the pre-treated solutions over RuO2 were faster degraded by anaerobic consortium than the raw oleate solutions or the electrolysed solutions using IrO2. In batch experiments carried out with pre-treated solutions over RuO2 (100-500mg/L), no lag phases were observed before the methane production onset. On the other hand, raw oleate and pre-treated oleate over IrO2 had originated lag phases of 0-140 and 0-210h, respectively. This study demonstrated that it is advantageous to apply the electrochemical treatment carried out on the RuO2 type DSA in order to achieve a faster biodegradation of lipid-containing effluent and consequently to obtain a faster methane production.

Effect of electrochemical treatment of oleic acid on anaerobic digestion.

Electrochemical pre-treatment of oleate on anaerobic digestion was investigated using two anaerobic filters (AF and AFm) working, respectively, with increasing concentrations of electrochemically pre-treated oleate and oleate. Influents containing 25% and 50% of chemical oxygen demand (COD) of these substrates did not cause relevant alterations in either digester's performance. Comparatively, the pre-treated oleate unit (AF) showed a higher gas production but a lower COD removal than AFm (2.0 vs 1.5 m(3) CH4 m(-3) d(-1) 76-85 vs 91-93% COD removal). The raised AFm COD removal together with the larger proportion of VSS in its effluent than in AF (5.69 vs 0.26 kg m(-3)) indicate that the biomass washout can be a consequence of the encapsulated solids by lipidic compounds that were not fairly degraded. Further increases of oleate in AFm feed (75 and 100% COD) led to decreases of biogas production to half and COD removal from values higher than 90% to 83-75%. The simultaneous increase of effluent VSS concentrations to 10-12 kg m(3) emphasizes the oleate negative effect. The use of pretreated oleate as the only carbon source did not influence negatively the AF behaviour in terms of methane production. COD removal was maintained at values higher than 80% and the effluent VSS at low concentrations (0.15 kg m(-3)). The significantly higher methane yield achieved by AF than AFm indicates a higher accumulation of oleate than pre-treated oleate. Therefore, electrochemical process stands for a suitable pre-treatment for lipid rich effluents, allowing the application of higher organic loads keeping a higher methane yield.