Comparison between Aliivibrio fischeri and activated sludge microorganisms in the evaluation of the toxic pollutants of leachates from Brazilian landfills.

Ecotoxicological assessment of landfill leachate has become a priority to determine its impacts on the ecosystem. Toxicity assays with microorganisms stand out due to their quick response, low cost and ease of testing. In this context, the present study evaluated the acute toxic effects of leachates from two landfills of different ages and modes of operation to bacterium Aliivibrio fischeri and activated sludge microorganisms and the ammonia nitrogen and humic substances (HS) sensitivity to these organisms. Reductions greater than 30% in leachate toxicity were observed after ammonia removal for A. fischeri and activated sludge microorganisms. After 97% removal of HS, the greater reductions in toxicity (44.28 to 79.82%) were verified for microbial species studied, indicating that the organic compounds (measured as chemical oxygen demand, total organic carbon and humic substances) were the primary pollutants responsible for the toxicity of the leachates. Concerning the organisms studied, A. fischeri showed greater sensitivity to the leachates' pollutants compared to the activated sludge microorganisms. Nevertheless, a strong correlation was observed between A. fischeri and activated sludge microorganisms' toxicity responses, suggesting that respirometry assay can be used to determine leachate toxicity.

Evaluation of toxic potential of leachate originating from experimental landfill cells containing household waste and healthcare waste.

Two experimental cells with household solid waste and healthcare solid waste were monitored in order to evaluate the pollution potential, and its toxicity effects corresponding to the chemical substances present in the leachates generated, correlating the physico-chemical composition with the ecotoxicity results (organisms Aliivibrio fischeri and Danio rerio). From the statistical evaluation of the physico-chemical analysis results, leachate generated in the household solid waste cell presented greater or equal values than to the healthcare solid waste cell, except for the turbidity parameter. The ecotoxicity results showed the same behaviour as that obtained with the physico-chemical analysis. A significant positive correlation was verified between chemical oxygen demand, alkalinity and ammonia nitrogen parameters with the leachate toxicity. This study concluded that healthcare solid waste presented less or equal polluting potential compared with household solid waste, and the co-disposal can be considered a viable alternative in sanitary landfills.

Landfill leachate treatment in Brazil - An overview.

The management of municipal solid waste (MSW) presents an ever increasing and more complex challenge in global terms. The disposal of MSW in landfills generates leachate, a liquid highly polluting to the aquatic environment. This review describes the state-of-the-art approaches to treatments applied to leachate in Brazil, highlighting the new technologies and alternatives that are still in the research phase, and compares the leachate treatment technologies applied around the world with the current scenario in Brazil. In Brazilian landfills, along with other technologies, the biological process is commonly applied, since this is a simple and economical approach and often it is the only technique used in small municipalities. The sanitary landfills in large Brazilian cities located in the states of São Paulo and Rio de Janeiro, invest in or outsource landfill activities, where apply advanced treatment technologies, such as membrane filtration. The use of membrane filtration technology in these cases reveals similarities with leachate treatments applied in the developed countries of North America and Europe. Brazilian researchers have highlighted the need to use efficient and economically viable technologies for the treatment of leachate in Brazilian landfills. However, the current scenario of MSW management in Brazil shows deficiencies related to the monitoring of sanitary landfills and limited information is available on the performance of leachate treatment systems.

Municipal solid waste in Brazil: A review.

The production of municipal solid waste (MSW) represents one of the greatest challenges currently faced by waste managers all around the world. In Brazil, the situation with regard to solid waste management is still deficient in many aspects. In 2015, only 58.7% of the MSW collected in Brazilian cities received appropriate final disposal. It was only as late as 2010 that Brazil established the National Policy on Solid Waste (NPSW) based on the legislation and programmes established in the 1970s in more developed countries. However, the situation with regard to MSW management has changed little since the implementation of the NPSW. Recent data show that, in Brazil, disposal in sanitary landfills is practically the only management approach to MSW. Contrary to expectations, despite the economic recession in 2015 the total annual amount of MSW generated nationwide increased by 1.7%, while in the same period the Brazilian population grew by 0.8% and economic activity decreased by 3.8%. The article describes the panorama with regard to MSW in Brazil from generation to final disposal and discusses the issues related to the delay in implementing the NPSW. The collection of recyclable material, the recycling process, the application of reverse logistics and the determination of the gravimetric composition of MSW in Brazil are also addressed in this article. Finally, a brief comparison is made between MSW management in Brazil and in other countries, the barriers to developing effective waste disposal systems are discussed and some recommendations for future MSW management development in Brazil are given.

Detection of replication-defective hepatitis A virus based on the correlation between real-time polymerase chain reaction and ELISA in situ results.

ELISA in situ can be used to titrate hepatitis A virus (HAV) particles and real-time polymerase chain reaction (RT-PCR) has been shown to be a fast method to quantify the HAV genome. Precise quantification of viral concentration is necessary to distinguish between infectious and non-infectious particles. The purpose of this study was to compare cell culture and RT-PCR quantification results and determine whether HAV genome quantification can be correlated with infectivity. For this purpose, three stocks of undiluted, five-fold diluted and 10-fold diluted HAV were prepared to inoculate cells in a 96-well plate. Monolayers were then incubated for seven, 10 and 14 days and the correlation between the ELISA in situ and RT-PCR results was evaluated. At 10 days post-incubation, the highest viral load was observed in all stocks of HAV via RT-PCR (10(5) copies/mL) (p = 0.0002), while ELISA revealed the highest quantity of particles after 14 days (optical density = 0.24, p < 0.001). At seven days post-infection, there was a significant statistical correlation between the results of the two methods, indicating equivalents titres of particles and HAV genome during this period of infection. The results reported here indicate that the duration of growth of HAV in cell culture must be taken into account to correlate genome quantification with infectivity.

Detection of replication-defective hepatitis A virus based on the correlation between real-time polymerase chain reaction and ELISA in situ results

ELISA in situ can be used to titrate hepatitis A virus (HAV) particles and real-time polymerase chain reaction (RT-PCR) has been shown to be a fast method to quantify the HAV genome. Precise quantification of viral concentration is necessary to distinguish between infectious and non-infectious particles. The purpose of this study was to compare cell culture and RT-PCR quantification results and determine whether HAV genome quantification can be correlated with infectivity. For this purpose, three stocks of undiluted, five-fold diluted and 10-fold diluted HAV were prepared to inoculate cells in a 96-well plate. Monolayers were then incubated for seven, 10 and 14 days and the correlation between the ELISA in situ and RT-PCR results was evaluated. At 10 days post-incubation, the highest viral load was observed in all stocks of HAV via RT-PCR (10(5) copies/mL) (p = 0.0002), while ELISA revealed the highest quantity of particles after 14 days (optical density = 0.24, p < 0.001). At seven days post-infection, there was a significant statistical correlation between the results of the two methods, indicating equivalents titres of particles and HAV genome during this period of infection. The results reported here indicate that the duration of growth of HAV in cell culture must be taken into account to correlate genome quantification with infectivity.