ABSTRACT
The generation of industrial waste is mainly dependent on several factors, including the type of industry, production capacity, technology use and raw materials involved in the manufacturing processes. The present study is a cross-sectional study that was conducted with 580 industries under six industrial sectors in Sri Lanka in 2022. The main objective of this research was to investigate solid waste generation and estimate the recyclable fraction in the waste. Furthermore, this study calculated the prevailing recycling rate of each industrial sector and the waste generation per person employed in the sector. Industrial processes, the types and quantities of waste, waste disposal methods and management activities in terms of recycling and disposal were evaluated through a structured questionnaire and random field observations. The study identified that the composition of selected recyclable items was 16.7% of the total waste generated in the industrial sector. The prevailing rate of recycling in different sectors was as follows: manufacturing of food products (36.6%), manufacturing of beverages (82.3%), manufacturing of textiles (68.6%), manufacturing of chemical and chemical products (28.5%), manufacturing of rubber and plastic (46.5%) and manufacturing of metallic mineral products (17.8%) from the total generated recyclable material. The study further estimated the waste intensity (waste generation per unit of product output) of the industrial sectors as follows: 0.38 (manufacturing of food products), 0.36 (manufacturing of beverages), 0.27 (manufacturing of textiles), 0.26 (manufacturing of chemical and chemical products), 0.17 (manufacturing of rubber and plastic) and 0.16 (manufacturing of non-metallic mineral products).
ABSTRACT
This study assessed the potential for minimizing human excreta bound phosphorus (P) loss through used disposable baby nappies, an area that remained unexplored for nations. Accordingly, it performed a substance flow analysis to assess the national P loss through used disposable baby nappies in the case of Australia. The analysis revealed that approximately 308 tonne P is lost through used baby nappies to landfills in Australia in 2019, which is nearly 2.5% of the overall P excreta as human waste. Although the quantity seems small in percentage term, it could result in the loss of a significant amount of P over several years, as assessed 5452 tonne P over the 2001-2019 period, which is concerning in the context of anticipated future global P scarcity. The review of peer-reviewed literature on available technologies/methods for recycling disposable baby nappy waste indicates that there are some technologies for recycling P particularly through co-composting with food and other organic wastes, while the majority of these are still at the lab/pilot scale. There are also various recycling techniques with purpose ranging from energy recovery to volume reduction, generation of pulp, hydrogel, cellulose, and polymer as well as to increase yield stress and viscosity of concrete, however, these are not effective in P recovery. The study implies that compost made of nappy waste can be used as fertilizer to produce bamboo, cotton, and maize plants to supply raw materials for producing biodegradable nappies, hence, to close the loop. The various product and system design options e.g., designing for flushing, designing for disassembling the excreta containing part, and designing for community composting suggested in this study could be further researched for identifying best suitable option to achieve P circular economy of disposable baby nappies. This study also recommends necessary interventions at various stages of the nappy life cycle to ensure sustainable management of phosphorus.
Subject(s)
Composting , Waste Management , Humans , Phosphorus , Polymers , Recycling , Waste Disposal FacilitiesABSTRACT
Concrete waste (CW) either reaches landfill with mixed waste or crushed to produce crushed concrete (CC) used as a road-base product in Australia. The coarse portion of CC, referred to as recycled concrete aggregate (RCA) has the potential to be used as an aggregate in structural concrete replacing natural aggregate (NA). The environmental performance of RAC has been studied in comparison to NAC, in terms of direct environmental implications (DEI) concerning the processes in the production chain of these products. However, when replacement at industry level is considered, the implications go beyond the DEI, and affect a series of other products/processes within a system boundary, referred to as indirect environmental implications (IEI). This paper quantifies the key IEI associated with the use of RCA in structural concrete and evaluates the external costs and benefits associated with it using economic evaluation methods. The net benefit associated with the avoidance of landfill of CW, extraction of NA, and transportation of waste and by-products are the major externalities identified and quantified in this paper. Evaluation of these suggest that there is a significant net benefit ranging from 9% to 28% of the price of natural aggregate concrete (NAC) with the production of recycled aggregate concrete (RAC), for RCA replacement rates between 30% and 100%.
