Valorisation of municipal organic waste through larval feeding activity of the black soldier fly, Hermetia illucens, constitutes a potential benefit, especially for low and middle-income countries. Besides waste reduction and stabilisation, the product in form of the last larval stage, the so-called prepupae, offers a valuable additive in animal feed, opening new economic niches for small entrepreneurs in developing countries. We have therefore evaluated the feasibility of the black soldier fly larvae to digest and degrade mixed municipal organic waste in a medium-scale field experiment in Costa Rica, and explored the benefits and limitations of this technology. We achieved an average prepupae production of 252 g/m²/day (wet weight) under favourable conditions. Waste reduction ranged from 65.5 to 78.9% depending on the daily amount of waste added to the experimental unit and presence/absence of a drainage system. Three factors strongly influenced larval yield and waste reduction capacity: (1) high larval mortality due to elevated zinc concentrations in the waste material and anaerobic conditions in the experimental trays; (2) lack of fertile eggs due to zinc poisoning, and (3) limited access to food from stagnating liquid in the experimental trays. This study confirmed the great potential of this fly as a waste manager in low and middle-income countries, but also identified knowledge gaps pertaining to biological larvae requirements (egg hatching rate, moisture tolerance, …) and process design (drainage, rearing facilities, …) to be tackled in future research.

Revista dirigida a especialistas y académicos interesados en la investigación y la búsqueda del conocimiento y soluciones de problemas relacionados con el agua.

Costa Rica followed different steps in order to organise and implement a waste of electrical and electronic equipment (WEEE) management system. This paper summarises the challenges, successes, and limitations of its implementation. Two phases were needed to set up the system. The first phase created a baseline followed by the designing of a strategy. The second phase promoted a Decree for WEEE management that prohibits discarding WEEE together with household waste, as well as the creation of a National Executive Committee with representatives of importers, consumers, and government, which will establish the quotes and treatment fees, and so on. Another outcome was the development of a strategy for the implementation of WEEE management for the country, the promotion of population awareness about their responsibility for WEEE management, and an example set up for other Latin American countries. This paper draws conclusions from the regulation and notes the required consistency with the existing national waste legislation in order to reduce approval times. Additionally, the importance of the participation of stakeholders representing different electric and electronic equipment (EEE) sectors with the purpose of obtaining consensus on agreements is highlighted.

Non-steroidal anti-inflammatory drugs are recognized widely as emerging contaminants. Sulindac has received additional attention as a prodrug in cancer treatment and because of its detection in drinking water and wastewaters. Nevertheless, there is limited knowledge about its kinetic behaviour and fate in the aquatic environment. In this work, the direct photolysis of sulindac, in which photochemical reactions were monitored and phototransformation products identified, was investigated under prolonged periods using UV-A and UV-B radiation and pH conditions (2 and 7) to evaluate the effect of the protonation state and the efficiency of the photolytic process. A novel kinetic mechanism has been proposed in which sulindac exhibits a consecutive reaction pathway, with pseudo-first order kinetics for rapid and reversible Z to E isomerization. Once photoequilibrium was reached, second-order degradation of the isomers in the presence of the new photodegradation products was observed. Photochemical transformation was faster under UV-B irradiation and lower pH, which suggests greater persistence of sulindac at more relevant environmental conditions of UV-A and pH 7. Two novel and major byproducts were identified, corresponding to the oxidative cleavage of the alkene exo to the indene system. The degradation pathway is mainly photoinduced, enhanced by acidic conditions and presumes the double bond as the most reactive site for the parent compound. This research demonstrates an approach for determining kinetics of compounds under challenging conditions, including, absorption from multiple electronic transitions, photoinduced products with unknown extinction coefficients, concentration dependence, photoinduced sensitizing intermediates, and speciation effects. Our work greatly improves our understanding of the degradation process of sulindac and will contribute to exposure assessments and treatment methodologies for this compound in impacted waters.

The polyene cyclization promoted by the cross conjugated α-carbomethoxy enone system has been successfully applied to facilitate the construction of the hydridane and hydroazulene framework containing a high level of functionalization.