Medios de cultivo económicos para la producción de un biocatalizador a células enteras para el tratamiento de aguas residuales que contienen Cr(VI) / Economical fermentation media for the production of a whole cell catalyst for the treatment of Cr(VI)-containing wastewaters

The biotechnology sector is continually seeking sustainable and more economical bioprocesses. Fermentation media produced with cheap components or wastes reduce production costs. Moreover, if wastes are used, they contribute to avoid environmental pollution. In this work, microbial growth media based on molasses or acidified glycerol as carbon sources and fertilizer as nitrogen source were tested for the production of a whole-cell catalyst that could be used in Cr(VI)-containing wastewater treatments. Results showed that the highest biomass production yield was obtained with a medium containing acidified glycerol 5% v/v and fertilizer 0.6% v/v. The biomass produced using this medium was immobilized in calcium alginate beads and used as catalyst in the biotransformation of Cr(VI) into Cr(III). The catalyst could be efficiently used for 5 reduction cycles of 40 mg/l Cr(VI) each. Cr(III) retention assays were performed to determine whether Cr(III) could be retained by the catalyst avoiding its solubilization in the supernatants. The retention capacity of the catalyst at 32 °C and pH 3.0 was 3 mg Cr(III)/g. Both an alternative and economical fermentation medium is here proposed for the optimization of Cr(VI)-containing wastewater treatment.

El sector industrial biotecnológico continuamente busca bioprocesos más económicos y sustentables. El uso de medios de cultivo producidos con componentes de bajo costo o con residuos reduce el presupuesto global del proceso y, particularmente si se utilizan residuos, se contribuye, además, a evitar la contaminación ambiental. En este trabajo se probaron medios de cultivo basados en melaza de caña o glicerol ácido como fuentes de carbono y energía, y fertilizante como fuente de nitrógeno, para la producción de un biocatalizador que podría ser usado para el tratamiento de aguas residuales que contienen Cr(VI). Los resultados mostraron que el mayor rendimiento de producción de biomasa se obtuvo con un medio que contenía 5% v/v de glicerol ácido y 0,6% v/v de fertilizante. Utilizando este medio se produjo la biomasa suficiente para la biotransformación de Cr(VI) a Cr(III), luego de ser inmovilizada en alginato de calcio. El proceso pudo ser aplicado eficientemente durante 5 ciclos de reducción de 40 mg/l de Cr(VI) cada uno. Además, se realizaron ensayos de retención de Cr(III) para determinar si esta especie química podría ser removida de la solución por interacción con el biocatalizador. La capacidad de retención obtenida por el biocatalizador a 32 °C y pH 3 fue de 3 mg de Cr(III)/g. De esta manera, se propone un medio de cultivo alternativo y económico para la efectivización de un tratamiento de aguas residuales que contengan Cr(VI).

Avaliação econômica de tecnologias sociais aplicadas à promoção de saúde: abastecimento de água por sistema Sodis em comunidades ribeirinhas da Amazônia / Economic evaluation of social technologies applied to health promotion: water supply by the SODIS System in riverside communities of the Brazilian Amazon

As chamadas tecnologias sociais vêm sendo largamente usadas em muitos lugares do mundo como alternativa viável para que populações de baixa renda tenham acesso a oportunidades de ocupação e renda e outros aspectos relacionados à qualidade de vida, inclusive o saneamento básico. O presente trabalho realiza uma avaliação custo-benefício do uso de uma tecnologia de baixo custo para abastecimento de água potável utilizada em vários países, o sistema SODIS. O estudo foi realizado em comunidades ribeirinhas que vivem na área insular do município de Belém (PA), localizado na Amazônia brasileira. Os dados foram obtidos por meio de questionários respondidos por famílias moradoras de três ilhas: Jutuba, Nova e Urubuoca. Os resultados mostraram-se positivos, considerando a análise de custo-benefício do projeto, o que comprova a viabilidade econômica do uso do sistema SODIS na situação investigada.

The so-called social technologies have been widely used in many places around the world as a viable alternative for low-income populations to gain access to opportunities for employment and income and other aspects related to quality of life, including basic sanitation. This paper conducts a cost-benefit analysis of using a low cost technology for drinking water used in several countries, namely the SODIS system. The study was conducted in riverside communities living in the island area of Belem municipality, located in the Brazilian Amazon. Data were collected through questionnaires answered by families living on three islands: Jutuba, Nova and Urubuoca. The results were positive, considering the cost-benefit analysis of the project, which demonstrates the economic viability of using the SODIS system in the situation investigated.

Technical and economic feasibility of gradual concentric chambers reactor for sewage treatment in developing countries

A major challenge in developing countries concerning domestic wastewaters is to decrease their treatment costs. In the present study, a new cost-effective reactor called gradual concentric chambers (GCC) was designed and evaluated at lab-scale. The effluent quality of the GCC reactor was compared with that of an upflow anaerobic sludge bed (UASB) reactor. Both reactors showed organic matter removal efficiencies of 90 percent; however, the elimination of nitrogen was higher in the GCC reactor. The amount of biogas recovered in the GCC and the UASB systems was 50 percent and 75 percent of the theoretical amount expected, respectively, and both reactors showed a slightly higher methane production when the feed was supplemented with an additive based on vitamins and minerals. Overall, the economical analysis, the simplicity of design and the performance results revealed that the GCC technology can be of particular interest for sewage treatment in developing countries.

[Effect of waste activated sludge pretreatment with ozone on the performance of aerobic digestion process]

A conventional treatment to stabilize the excess activated sludge is the aerobic digestion process but due to long aeration time, it requires large equipments as well as high investment cost. Because of high oxidation potential of ozone, sludge ozonation enhances stabilization rate and reduces sludge treatment equipment size and cost. Therefore, in this study, the combination of pretreatment with ozone and aerobic digestion processes were investigated. The experimental set-up consisted of an ozone generator and ozonation reactor with the total volume of 2 L. Removal percentages of TSS, VS, total and soluble COD, HPC, fecal coliform and settable solids were measured in integrated process compared to the single ones. The results of this research indicated that the aerobic digestion of waste activated sludge during 10 days could reduce 38% of volatile solids and thus obtaining the EPA standard. Also, the results of combined ozonation and aerobic digestion revealed that the pre-ozonation at 0.25 g O3/g TS or 0.5 g O3/g TS with 6 or 3 days aeration, respectively, could achieve 38% reduction in VS and hence the requirement set by EPA. Therefore, integration of pre-ozonation with aerobic digestion can significantly reduce the digestion time to attain the standards. The sludge pre-ozonation with low dose of ozone due to solids disintegration can enhance the efficiency of aerobic digestion in waste activated sludge stabilization, and consequently decrease size of equipments, air requirement, investment and probably operation cost

Removal of lead from aqueous effluents by adsorption on coconut shell carbon.

The application of adsorption for removal of heavy metals is quite popular and activated carbon is universally used as an adsorbent. However, high cost of its preparation and regeneration has led to a search for alternative sorbents, especially in the developing countries. A number of sorbents are used to remove metals by adsorption from industrial effluents, which include insoluble starch, xanthates, modified cotton and wool, tree barks, activated carbon, plant leaves and agricultural products. Therefore, as an alternative, coconut shell carbon (CSC), a low cost sorbent derived from organic waste material, was used in the present work, for removal of lead from aqueous effluents. The results of the batch sorption studies indicated that the efficiency of lead removal by coconut shell carbon is comparable to that of commercially available activated carbon. From the kinetic and equilibrium studies, the sorptive capacity of coconut shell carbon for lead was found to be 30 mg/g. Desorption and subsequent recovery of the metal from the surface of the sorbent was successfully demonstrated. Parameters affecting the sorption were evaluated.

One solution to the arsenic problem: a return to surface (improved dug) wells.

Arsenic contamination in drinking-water in Bangladesh is a major catastrophe, the consequences of which exceed most other man-made disasters. The national policy encourages the use of surface water as much as possible without encountering the problems of sanitation that led to the use of groundwater in the first place. This paper describes the success of the Dhaka Community Hospital (DCH) team and the procedure in implementing sanitary, arsenic-free, dugwells. The capital cost for running water is US$ 5-6 per person. Sixty-six sanitary dugwells were installed in phases between 2000 and 2004 in Pabna district of Bangladesh where there was a great need of safe water because, in some villages, 90% of tubewells were highly contaminated with arsenic. In total, 1,549 families now have access to safe arsenic-free dugwell water. Some of them have a water-pipe up to their kitchen. All of these were implemented with active participation of community members. They also pay for water-use and are themselves responsible for the maintenance and water quality. The DCH helped the community with installation and maintenance protocol and also with monitoring water quality. The bacteria levels are low but not always zero, and studies are in progress to reduce bacteria by chlorination.

Removal of fluoride from water with powdered corn cobs.

The adsorption of fluoride on corn cobs powder was investigated in the present study. Neat powdered corn cobs did not show remarkable adsorption but aluminium treated corn cobs had good adsorption capacity. The parameters studied include the contact time, concentration, temperature and pH. Near neutral pH was identified as the optimum condition of the medium, and 90 to 120 minutes was the best contact time for maximum fluoride adsorption. The adsorption process was found to follow Freundlich isotherm. The adsorption process was found to be exothermic as adsorption decreased with increasing temperature.

Pura h2o suja / Pure h2o dirty

Realizado com o objetivo de sensibilizar a população da grande Curitiba para a importância da prevenção dos rios que a abastecem.