The study presented here aims at identifying the source of redox mediators (riboflavin), electron carriers nicotinamide adenine dinucleotide (NAD) and carbon to perform decolorization of azo dye under anaerobic conditions after osmotic shock pretreatment of residual yeast from industrial fermentation. Pretreatment conditions were optimized by Doehlert experiment, varying NaCl concentration, temperature, yeast density and time. After the optimization, the riboflavin concentration in the residual yeast lysate (RYL) was 46% higher than the one present in commercial yeast extract. Moreover, similar NAD concentration was observed in both extracts. Subsequently, two decolorization experiments were performed, that is, a batch experiment (48 h) and a kinetic experiment (102 h). The results of the batch experiment showed that the use of the RYL produced by the optimized method increased decolorization rates and led to color removal efficiencies similar to those found when using the commercial extract (∼80%) and from 23% to 50% higher when compared to the control (without redox mediators). Kinetics analysis showed that methane production was also higher in the presence of yeast extract and RYL, and biogas was mostly generated after stabilization of color removal. In all kinetics experiments the azo dye degradation followed the pseudo-second-order model, which suggested that there was a concomitant adsorption/degradation of the dye on the biomass cell surface. Therefore, results showed the possibility of applying the pretreated residual yeast to improve color removal under anaerobic conditions, which is a sustainable process.

The outbreak of the new coronavirus disease (COVID-19) led to an unprecedented number of policy responses from public institutions involved in the health and economic sectors. Nonetheless, the water, sanitation, and hygiene (WASH) sector remained in the background of this decision-making arena. The objective of the study presented herein was to observe and discuss political responses to the new coronavirus pandemic in the context of WASH during the first 40 days of the outbreak, using as cases the five Brazilian states most affected by the pandemic. We addressed this issue with a quali-quantitative exploratory study using content analysis to discuss the direction (for whom and how?) of those policy responses, through the framework of the human rights to water and sanitation. The paper also introduces a timeline to map the reactivity and proactivity of the studied institutions. We identified two major priorities in policy responses to the coronavirus pandemic: population protection and financial and economic sustainability of service providers. In regard to population protection, the findings show that it often did not contemplate all of the population, and that equality and non-discriminations were partially ignored in the laws and regulations. In addition, institutions more attached to service providers were more committed to the provider’s economic and financial sustainability than to measures to directly protect the population.

Droughts affect semiarid regions worldwide, threatening economic activities and lives of people living in these places. In Brazil, 11% of the population inhabits the semiarid, and despite several mitigation measures taken by the State, it is still ranked as the most vulnerable Brazilian region and potentially the most affected by climate change. Throughout Brazilian history several public policies focused on water supply in the semiarid region have failed for different reasons. Two recurring arguments are the lack of financial resources and poor management. This work presents an analysis of a public policy that aims to provide quality and perennial water by desalting local brackish groundwater, the Programa Água Doce (PAD). We used the ecodevelopment theory to discuss the economic sustainability of the policy. The methodology used was a documental analysis, and a literature review to understand PAD’s main strengths and weaknesses. We found that the continuous flow of public and private investment was a decisive element to the implementation of the technology during the initial transference of responsibilities moment. In addition, by the gradual reduction of public investment, the management of the systems became local and funded by private resources from the beneficiaries. The PAD presents, in its dynamics, advances in the field of the dissemination of water treatment technologies and social technologies, especially in relation to the Management Agreements. However, the lack of processes for community empowerment and no strengthening of cooperativism resulted in disconnected systems that were not able to ensure economic sustainability.

-This work investigated the anaerobic degradation of the model azo dye Remazol Yellow Gold RNL in batch reactors using discharged residual yeast as the source of redox mediators (RM). Two yeast lysis methods (mechanical lysis and sonication) were tested and optimized to produce a riboflavin-rich yeast lysate. The reactors were operated at 25 o C for 48 hours, evaluating the effect of external carbon source (glucose) and RM (from residual yeast lysate and commercial yeast extract) addition. The results showed that color removal efficiencies for the batch reactors fed with commercial yeast extract reached 90%, whereas those fed with discharged yeast lysate reached 80% (sonication) and 73% (mechanical lysis). These values were statistically higher when compared to reactors operating without RM (48 to 66%), demonstrating that yeast extract enhances azo dye degradation in anaerobic conditions and that the residual yeast is a cheap and alternative source of carbon and of the RM riboflavin.

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