Gas quantity and composition from the hydrolysis of salt cake from secondary aluminum processing

A systematic approach to understanding the hydrolysis of salt cake from secondary aluminum production in municipal solid waste landfill environment was conducted. Thirty-nine (39) samples from 10 Aluminum recycling facilities throughout the USA were collected. A laboratory procedure to assess the gas productivity of SC from SAP under anaerobic conditions at 50 °C to simulate a landfill environment was developed. Gas quantity and composition data indicate that on average 1400 µmol g^-1 (35 mL g^-1) of gas resulted from the hydrolysis of SC. Hydrogen was the dominant gas generated (79% by volume) followed by methane with an average of 190 µmol g^-1 (21% by volume). N₂O was detected at a much lower concentration (1.2 ppmv). The total ammonia released was 680 µmol g^-1, and because of the closed system nature of the experimental setup, the vast majority of ammonia was present in the liquid phase (570 mg L^-1). In general, the productivity of both hydrogen and total ammonia (the sum of gas and liquid forms ammonia) was a fraction of that expected by stoichiometry indicating an incomplete hydrolysis and a potential for re-hydrolysis when conditions are more favorable. The result provides substantial evidence that SC can be hydrolyzed to generate a gas with relative long-lasting implications for municipal solid waste landfill operations.

Integrating science and business models of sustainability for environmentally-challenging industries such as secondary lead smelters: a systematic review and analysis of findings

Secondary lead smelters (SLS) represent an environmentally-challenging industry as they deal with toxic substances posing potential threats to both human and environmental health, consequently, they operate under strict government regulations. Such challenges have resulted in the significant reduction of SLS plants in the last three decades. In addition, the domestic recycling of lead has been on a steep decline in the past 10 years as the amount of lead recovered has remained virtually unchanged while consumption has increased. Therefore, one may wonder whether sustainable development can be achieved among SLS. The primary objective of this study was to determine whether a roadmap for sustainable development can be established for SLS. The following aims were established in support of the study objective: (1) to conduct a systematic review and an analysis of models of sustainable systems with a particular emphasis on SLS; (2) to document the challenges for the U.S. secondary lead smelting industry; and (3) to explore practices and concepts which act as vehicles for SLS on the road to sustainable development. An evidence-based methodology was adopted to achieve the study objective. A comprehensive electronic search was conducted to implement the aforementioned specific aims. Inclusion criteria were established to filter out irrelevant scientific papers and reports. The relevant articles were closely scrutinized and appraised to extract the required information and data for the possible development of a sustainable roadmap. The search process yielded a number of research articles which were utilized in the systematic review. Two types of models emerged: management/business and science/mathematical models. Although the management/business models explored actions to achieve sustainable growth in the industrial enterprise, science/mathematical models attempted to explain the sustainable behaviors and properties aiming at predominantly ecosystem management. As such, there are major disconnects between the science/mathematical and management/business models in terms of aims and goals. Therefore, there is an urgent need to integrate science and business models of sustainability for the industrial enterprises at large and environmentally-challenging industrial sectors in particular. In this paper, we offered examples of practices and concepts which can be used in charting a path towards sustainable development for secondary lead smelters particularly that the waste generated is much greater outside the industrial enterprise than inside. An environmentally-challenging industry such as secondary lead smelters requires a fresh look to chart a path towards sustainable development (i.e., survivability and purposive needs) for all stakeholders (i.e., industrial enterprise, individual stakeholders, and social/ecological systems). Such a path should deal with issues beyond pollution prevention, product stewardship and clean technologies.

Evidence-based integrated environmental solutions for secondary lead smelters: pollution prevention and waste minimization technologies and practices

An evidence-based methodology was adopted in this research to establish strategies to increase lead recovery and recycling via a systematic review and critical appraisal of the published literature. In particular, the research examines pollution prevention and waste minimization practices and technologies that meet the following criteria: (a) reduce/recover/recycle the largest quantities of lead currently being disposed of as waste, (b) technically and economically viable, that is, ready to be diffused and easily transferable, and (c) strong industry interest (i.e., industry would consider implementing projects with higher payback periods). The following specific aims are designed to achieve the study objectives: Aim 1 - To describe the recycling process of recovering refined lead from scrap; Aim 2 - To document pollution prevention and waste management technologies and practices adopted by US stakeholders along the trajectory of LAB and lead product life cycle; Aim 3 - To explore improved practices and technologies which are employed by other organizations with an emphasis on the aforementioned criteria; Aim 4 - To demonstrate the economic and environmental costs and benefits of applying improved technologies and practices to existing US smelting operations; and Aim 5 - To evaluate improved environmental technologies and practices using an algorithm that integrates quantitative and qualitative criteria. The process of identifying relevant articles and reports was documented. The description of evidence was presented for current practices and technologies used by US smelters as well as improved practices and technologies. Options for integrated environmental solutions for secondary smelters were introduced and rank ordered on the basis of costs (i.e., capital investment) and benefits (i.e., production increases, energy and flux savings, and reduction of SO(2) and slag). An example was provided to demonstrate the utility of the algorithm by detailing the costs and benefits associated with different combinations of practices and technologies. The evidence-based methodology documented in this research reveals that it is technically and economically feasible to implement integrated environmental solutions to increase lead recovery and recycling among US smelters. The working example presented in this research can be confirmed with US stakeholders and form the basis for implementable solutions in the lead smelter and product industries to help reverse the overall trend of declining life-cycle recycling rates.

An exploratory study of lead recovery in lead-acid battery lifecycle in US market: an evidence-based approach

BACKGROUND

This research examines lead recovery and recycling in lead-acid batteries (LAB) which account for 88% of US lead consumption. We explore strategies to maximize lead recovery and recycling in the LAB lifecycle. Currently, there is limited information on recycling rates for LAB in the published literature and is derived from a single source. Therefore, its recycling efforts in the US has been unclear so as to determine the maximum opportunities for metal recovery and recycling in the face of significant demands for LAB particularly in the auto industry.

OBJECTIVES

The research utilizes an evidence-based approach to: (1) determine recycling rates for lead recovery in the LAB product lifecycle for the US market; and (2) quantify and identify opportunities where lead recovery and recycling can be improved.

METHODS

A comprehensive electronic search of the published literature was conducted to gather information on different LAB recycling models and actual data used to calculate recycling rates based on product lifecycle for the US market to identify strategies for increasing lead recovery and recycling.

RESULTS

The electronic search yielded five models for calculating LAB recycling rates. The description of evidence was documented for each model. Furthermore, an integrated model was developed to identify and quantify the maximum opportunities for lead recovery and recycling. Results showed that recycling rates declined during the period spanning from 1999 to 2006. Opportunities were identified for recovery and recycling of lead in the LAB product lifecycle.

CONCLUDING REMARKS

One can deduce the following from the analyses undertaken in this report: (1) lead recovery and recycling has been stable between 1999 and 2006; (2) lead consumption has increased at an annual rate of 2.25%, thus, the values derived in this study for opportunities dealing with lead recovery and recycling underestimate the amount of lead in scrap and waste generated; and (3) the opportunities for maximizing lead recovery and recycling are centered on spent batteries left with consumers, mishandled LAB sent to auto wreckers, slag resulting from recycling technology process inefficiencies, and lead lost in municipal waste.