Valorização agronómica/energética de lamas de ETAR

Mestrado em Engenharia do Ambiente - Instituto Superior de AgronomiaThis work aims to evaluate the use of 4 different sewage sludges as a fertilizer: mixed sewage sludge (primary+secondary sludge), dehydrated mixed sewage sludge; anaerobically digested sewage sludge and anaerobically digested sewage sludge treated with quicklime (CaO). Two aerobic incubations were performed with mixtures of sludge and the top layer of a Haplic Pdzol, at a rate equivalent to 10 ton dry matter ha- 1. During 140 days, the CO2-C emissions and the mineral N in soil were periodically measured. At the end of the incubation period, several soil properties were evaluated. The higher CO2-C emission was found in the mixed sludges while the anaerobic sludge presented the lower value. The treatment of anaerobic sludge with lime led to an increase of CO2-C emission and nitrogen mineralization from the sludge, indicating that lime treatment promoted more favorable conditions to sludge mineralization. At the end of the incubation period, sludge-amended soil had higher pH, more evident on the lime-treated sludge, and higher amounts of available nutrients, namely, nitrogen, phosphorus, potassium and calcium. The balance between applied carbon and C-CO2 emission, proved that sewage sludge increases carbon accumulation in soil

A water treatment strategy using Moringa oleifera (Lam) to prevent waterborne diseases in Guinea-Bissau

Waterborne infections remain a public health concern mainly in developing countries. Despite control initiatives undertaken by local and international authorities, namely the introduction of water, sanitation, and hygiene (WASH) policies and practices, in 2019, 702.974 cases of diarrhoea were reported in Biombo, an administrative region in northern (Guinea-Bissau). Therefore, promoting the adherence of the community to preventive practices has become an even major priority in order to reduce the rate of diarrhoeal diseases in the country. Due to the absence of a piped water distribution system, in most of the territory, and the community’s resistance to the most promoted household water treatment strategies such as chlorine and boiling, moringa has emerged as a promising strategy. This naturalized plant, easily found in all country have been showing water purifying effects in the recent literature. The present work started in 2018, by understanding what is known in general regarding moringa concerning its antimicrobial activity and its potential for water purification. For this purpose, an extensive literature review was conducted to clearly identify which parts of the plant are used, as well as the most effective extraction methods and concentrations for a greater number of pathogens. This review allowed us to clearly identify the part of the plant used, as well as the methods and the most effective concentration for a higher number of pathogens for antibacterial activity. The second step was to try to understand which are the hotspot areas for certain kinds of diseases such as (diarrhoeal diseases) in Guinea-Bissau, and which are the most contaminated water sources and which pathogens are present in these waters. For this purpose, we collected water samples in both dry and wet seasons and analyzed the physical-chemical and microbiological parameters of the three types of drinking water sources (Piped water, tubewell water2, and shallow well water3) in Bissau (urban) and its surroundings (peri-urban) and Quinhamel (rural). Simultaneously we collected samples of the moringa plant in four localities in Guinea-Bissau, made extracts in distilled water and ethanol, and tested their efficiency in Petri dishes in contaminated water in the laboratory, selecting the two pathogens responsible for gastrointestinal diseases most commonly found in water. Finally, we carried out social studies aimed at understanding the local community's perception of moringa before and after they tried it as a viable alternative for domestic water treatment, as well as its private and public management implications. In this context, qualitative focus group discussion and quantitative survey studies were carried out in a selected community. The results of the systematic review showed that there is no single effective method for all pathogens and that the concentrations used vary. Regarding the extract for antibacterial activity, the leaf is the part used, while the seed powder is used as a coagulant in the water treatment process. However, extraction with ethanol and distilled water showed to be the most effective for the highest number of pathogens at the concentration of 30 mg mL-1. Regarding the analysis of the three types of drinking water sources in Guinea-Bissau, the results show that all water sources present strong faecal contamination with greater emphasis on shallow wells, followed by tubewells and finally water supply system. In water supply systems, contamination tends to increase from the hole to the final consumer. In general, contamination tends to increase during the wet season for all three types of water sources. Moringa extracts are shown to have antibacterial activity and inhibit microbial growth. Of the two methods of extraction used (ethanol and distilled water), ethanol shown to be more effective than distilled water. These results are in agreement with those found in the literature, thus reinforcing that ethanol extracts are the most effective. For the social studies, results from both qualitative and quantitative analyses were consistent in identifying community perceptions that hinder adherence to household water treatment practices. The community, in general, showed great openness to the use of moringa and even buying it, and in general consider moringa much better than other methods. Overall, the main community perceptions observed as hindering the adherence to water treatment practices at the household level are: chlorine’s smell, change in taste of the water after the use of chlorine, difficulties in reaching chlorine or firewood to boil the water, time and financial issues among others. On the other hand, moringa is seen as a natural and odourless product, easily accessible and with nutritional and medicinal capacities. However, its availability throughout the year, conservation, and the moringa seed powder/water ratio are some of the difficulties presented. This work probably constitutes the most comprehensive study to date on the use of moringa as an alternative for domestic water treatment. It is thus hoped that the findings of this study can enhance the effectiveness of prevention and reduction of waterborne infectious diseases in endemic and epidemic regions at national and sub-regional levels