Volume 20 - 2018

The circular economy approach represents a strategy to optimize product lifecycles, thus improving the sustainability of consumption patterns. In the European Union a recent legislative proposal has addressed this concept by promoting waste prevention and re-use as well as extensive recovery of materials. Such approach is particularly interesting for the management of Waste Electrical and Electronic Equipment (WEEE), that is regarded as an urban stock of different metals, and in particular of both precious metals and rare earth elements. The recovery of metals is the main focus of WEEE management strategies and, more recently, it has been receiving a great deal of attention, especially due to the continuously increasing production of this waste stream. However, great room for improvements can still be recognised to ensure the overall sustainability of WEEE management. The present work discusses both the current needs and the main challenges regarding WEEE management in a circular economy perspective. To this end, WEEE generation trend and composition is provided and the legislative framework for its handling is overviewed, in order to point out future perspectives to develop a more sustainable management approach of this waste.

In this study, a new technology was introduced to monitor the odor occurrence situation at the remote site in real time and the technology to reduce sewage odor by using microbial deodorant. Long-term monitoring and full-scale test was carried out to investigate the odor concentration in the combined sewer using the real - time odor monitoring device which consist of 3 odor sensors with the wireless communication technique, and to investigate the effect of the microbial deodorant on the reduction of sewer odor. The odor monitoring device, which was fabricated using metal oxide semiconductor sensors and code division multi access communication technique, was installed at three sites of the gravity-flow type combined sewer (depth 3m and width 5m) in Gangnam, Seoul. Odor monitoring in field was carried out at the interval of 10 minutes for 304 days over the autumn, winter and summer. The measured results were transmitted to Woosong odor research center about 100km away from the site. The measured sensor value was converted to olfactory odor concentration by the co-relation equation of the sensor value and the olfactory odor concentration. As the monitoring results, more than 40,000 sewage odor data were obtained. The average odor concentration of raw sewage in combined sewer was 464 OUk, which was 321 OUk in winter and 412 OUk in autumn and 659 OUk in summer. The commercial microbial deodorant used in this study was the mixture culture of 48 microbial strains, and the microbial deodorant of 1 m3 d-1 to 2 m3 d-1 was mixed with raw sewage at the 1.5 km upstream of the site where odor complaints occurred. As the experimental results, the average odor concentration of sewage mixed with microbial deodorant was 113 OUk, which was 102 OUk in winter and 298 OUk in autumn and 153 OUk in summer. It was estimated that the odor reduction effect of sewer odor by microbial deodorant is about 74%.

The growing expectations of the population and the increasingly stringent regulations about air pollution have resulted in the need to minimize and conveniently treat the waste gas from different emission sources. The emissions from a large variety of plants, including waste and wastewater treatment plants, result mainly from the degradation of organic matter. These emissions are composed of a complex of substances emitted at low concentrations from diffusive sources. These characteristics make complex their treatment in economically efficient conditions. The design and management of environmental protection and industrial plants, therefore, require the implementation of focused processes for the control of the target compounds. The present study shows the applicability of an UV-Ozone lab-scale system for odours and VOCs removal. An artificial gaseous stream contaminated by toluene, at different incoming concentrations, was treated evaluating the abatement efficiencies in terms of odours and total VOCs as a function of power and contact time. The residue ozone concentrations was determined in order to optimize the set-up conditions. The results were discussed with the aim of evaluating the feasibility of the investigated solution for the advanced treatment of the waste gas from environmental facilities. Removal efficiencies up tp 91% were reached for the investigated conditions. Lower inlet concentrations resulted in high residue ozone outgoing the processes and, thus, it resulted over dimensioned for inlet load lower than 1,22 mg per minute.

The mineral sequestration, one of the methods of CO2 sequestration, is considered advantageous, as it not only facilitates permanent and leakage free storage of CO2 but also obviates the need for regular monitoring. Mineral sequestration involves the dissolution of minerals and subsequently carbonation of dissolved minerals. In the direct mineral sequestration all the processes occur within a single reactor, whereas in the cases of indirect mineral sequestration, they take place in separate reactors. The main aim of the present study is to investigate the efficacy of these mineral sequestration methods and examine their suitability for industrial application and ensuring environmental friendliness. For this purpose, literature pertaining to these methods was extensively reviewed, and observations made by several researchers were collected, collated and compared based on the various parameters such as reaction pathways, reaction kinetics and cost of the process. The process cost was found to depend on the type of the process, process parameters, input materials and additives. It was noted that the direct mineral sequestration suffers from the sluggish reaction kinetics, thereby becomes economically unviable. The success of direct mineral sequestration process is yet to be achieved despite research carried out for several years. The problem of sluggish reaction kinetics was overcome by using multi-steps indirect carbonation routes, where separate reactors were used for dissolution and precipitation processes. The indirect sequestration method was noted to be most efficient as it offered several advantages such as improved reaction kinetics and recovery of the market value of by-product due to the better quality control of the product. Hence, based on interpretation of an extensive review of literature it can be concluded that the indirect mineral sequestration may be a viable option to carry out the CO2 sequestration and may be proved as a guiding light to ensure the clean environment for future generation.