Resource Recovery Plants Research Articles

The water-soluble fraction of extracellular polymeric substances from a resource recovery demonstration plant: characterization and potential application as an adhesive.

Currently, there is a growing interest in transforming wastewater treatment plants (WWTPs) into resource recovery plants. Microorganisms in aerobic granular sludge produce extracellular polymeric substances (EPS), which are considered sustainable resources to be extracted and can be used in diverse applications. Exploring applications in other high-value materials, such as adhesives, will not only enhance the valorization potential of the EPS but also promote resource recovery. This study aimed to characterize a water-soluble fraction extracted from the EPS collected at the demonstration plant in the Netherlands based on its chemical composition (amino acids, sugar, and fatty acids) and propose a proof-of-concept for its use as an adhesive. This fraction comprises a mixture of biomolecules, such as proteins (26.6 ± 0.3%), sugars (21.8 ± 0.2%), and fatty acids (0.9%). The water-soluble fraction exhibited shear strength reaching 36-51 kPa across a pH range of 2-10 without additional chemical treatment, suggesting a potential application as an adhesive. The findings from this study provide insights into the concept of resource recovery and the valorization of excess sludge at WWTPs.

Assessing the equivalence of WRRF regulations using dynamic model simulations.

A wide diversity of regulatory practices for wastewater resource recovery plants exists throughout the world. This contribution aims to highlight the implications of choosing particular permitting structures and investigate the equivalence of effluent standards in terms of limit values and compliance assessment specifications. These factors heavily affect the true performance that a treatment plant has to attain and thus the required plant capacity and operation. The dynamic simulations executed in this work, based on a realistic case study and three selected permits from China, The Netherlands and the USA, show the impact of certain compliance specifications like sampling frequency, averaging and tolerable permit exceedances leading to differences in the required design capacity of more than 250% for the same wastewater to be treated. The results also reveal clear differences between permits in their capacity to handle excess variability. The latter is important to avoid overdesign, i.e., when further investment in treatment capacity would result only in marginal effluent quality gains, as well as to create a safe space for testing innovative technologies or ways of operation that might otherwise trigger compliance issues.

Anaerobic Membrane Bioreactors (AnMBRs) for Wastewater Treatment: Recovery of Nutrients and Energy, and Management of Fouling

Anaerobic membrane bioreactor (AnMBR) technology is emerging as an alternative to conventional anaerobic treatment due to its complete biomass retention, short start-up time, high effluent quality, and small footprint. This paper provides a general overview of the application of AnMBRs for industrial and municipal wastewater treatment. The potential benefits of AnMBRs are discussed, such as the degradation of organic matter for energy production, the concentration of nutrients for subsequent reclamation, or the effective removal of organic contaminants for water reuse. To explore the technology for energy-neutral wastewater treatment, the recovery of methane, hydrogen, and ethanol is summarized, highlighting the problems of dissolution of methane in permeate and competition between sulfate-reducing bacteria and methanogens for organic matter. Recovery of water and nutrients for reuse, e.g., for algae production, is reported. Since membrane fouling remains a challenge in membrane operation and leads to increased operation and maintenance costs, methods to reduce fouling are highlighted. Future research prospects related to the application of AnMBR in resource recovery plants and fouling management are emphasized.

Digital tool for driving circular economy outcomes in the Australian red meat industry

This study presents the development of a novel digital tool aimed at facilitating the preliminary sizing and economical evaluation of integrated resource management facilities for wastewater treatment in red meat processing plants. The tool is designed to transform conventional wastewater treatment facilities in these plants into resource recovery plants, with a strong emphasis on enhancing environmental compliance and reducing the overall carbon footprint. Key objectives include the reduction of nutrient emissions, wastewater recycling, waste minimisation, and biogas energy production. The framework for developing this digital tool incorporates considerations of scale, the urgency of wastewater issues outlined by the Environmental Protection Authority (EPA) for Australian red meat processors, and adaptability for plants of varying sizes. By providing decision support for wastewater treatment and waste management, this model aims to assist the red meat processing industry in aligning with net-zero goals through resource recovery and the adoption of a circular economy.

The assessment of reuse potential for municipal solid waste and refuse-derived fuel incineration ashes

Resource recovery plants with a waste presorting process prior to incineration have not been successfully implemented in many developing countries. At least two engineering projects were fully assessed in Taiwan for the possible installation of presorting facilities in order to increase the potential efficiency of material and energy recovery for municipal incinerators. But the reuse potential of incineration ash in light of toxicity leaching and compressive strength of concrete mixture remains unclear due to the lack of comprehensive evaluation for the ash characteristics. A comparative study for assessing the reuse potential of incineration ash based on two types of incineration processes was therefore performed in this study. The experimental results indicate that fly ash collected from both types of incineration processes is classified as a hazardous material because of their leachable metal contents. For the reuse of bottom ash as fine aggregate in concrete mixing, the refuse-derived fuel (RDF) incineration process shows higher potential than the solid waste incineration process without any presorting unit. But the concrete mixture with RDF incineration ash still presents a lower compressive strength by 23% as compared with the concrete made with conventional aggregate.

The use of mathematical models in evaluating resource recovery options

The financial, physical and environmental impacts of a major resource recovery facility on an existing waste management system are complex and the need to resort to computer assistance in the prediction and assessment of these impacts is demonstrated. The basic requirements of a mathematical model are reviewed and specific reference is made to the HARBINGER model. The extent to which this model can be used to evaluate resource recovery plants is discussed and a number of related conservation issues which the model can address are considered.

Biological health risk associated with resource recovery, sorting of recycle waste and composting

Abstract Numbers of airborne microorganisms, fungi, Gram-negative bacteria, thermophilic microorganisms, endotoxins and dust have been monitored in resource recovery plants and composting plants. The work is still in progress, so this paper decribes only preliminary results. Only low levels (< 15 ng m−3) of endotoxins were found at all locations. Levels of microorganisms, fungi, Gram-negative bacteria and dust changed with quality of waste, activity in the plant etc. Levels of airborne microorganisms, endotoxins and dust could be considerably decreased in resource recovery plants if only waste of good quality, e.g. presorted materials, is handled. For composting plants the highest levels of airborne microorganisms were found during aeration, especially by indoor composting where levels of 8.3 × 105 CFU of mesophilic microorganisms were found.

Sources and Fates of Lead and Cadmium in Municipal Solid Waste

Lead and cadmium enter the municipal solid waste stream as components of a variety of consumer products. Average empirical data from several resource recovery plants were analyzed to obtain an estimate of the source and fate of the subject elements. The total amounts of lead and cadmium found in municipal solid waste, determined from empirical data sources, were found to agree closely with those based on materials flow data. It was determined that most of the cadmium enters the waste stream in the combustible fraction and can account for a major share of the cadmium observed in fly ash and in atmospheric particulates. The most likely sources of cadmium are plastics and pigments. The lead emissions appeared to be derived from both combustible and noncombustible discards of batteries, plastics, and pigments. The data suggests that it would be useful to perform mass balance studies to provide primary data for the determination of the most effective methods for managing discards containing lead and cadmium. The purpose of the suggested research is the reduction of lead and cadmium emissions into the environment from resource recovery plants.

The impact of the dioxin issue on resource recovery in the United States

Alternative solutions to the solid waste disposal crisis include recycling and waste reduction and large-scale energy and materials recovery facilities (known as resource recovery and RDF, respectively). The discovery of dioxin and furan emissions from resource recovery plants has led to an intensive focus on the dioxin issue by the public, the regulators, and the builders of the plants. This paper discusses the issues concerning dioxin currently being debated by the scientific community, including dioxin and furan toxicity in animals (and extrapolation to humans), toxic equivalents, the processes of dioxin formation in resource recovery plants, the role of source separation of plastics and paper from refuse in mitigation of dioxin formation, and the roles of combustion-regulation and air-pollution control devices in the destruction and reduction of dioxin emissions. In addition, the steps that the New York City Sanitation Department has chosen for exploring the health risk of dioxin emissions (the Fred C. Hart Risk Assessment) and to reduce emissions of dioxins from its proposed resource recovery plants (both in terms of combustion regulation and control devices) are discussed.

The Impact of the Dioxin Issue On Resource Recovery in the United States

Alternative solutions to the solid waste disposal crisis include recycling and waste reduction and large-scale energy and materials recovery facilities (known as resource recovery and RDF, respectively). The discovery of dioxin and furan emissions from resource recovery plants has led to an intensive focus on the dioxin issue by the public, the regulators, and the builders of the plants. This paper discusses the issues concerning dioxin currently being debated by the scientific community, including dioxin and furan toxicity in animals (and extrapolation to humans), toxic equivalents, the processes of dioxin formation in resource recovery plants, the role of source separation of plastics and paper from refuse in mitigation of dioxin formation, and the roles of combustion-regulation and air-pollution control devices in the destruction and reduction of dioxin emissions. In addition, the steps that the New York City Sanitation Department has chosen for exploring the health risk of dioxin emissions (the Fred C. Hart Risk Assessment) and to reduce emissions of dioxins from its proposed resource recovery plants (both in terms of combustion regulation and control devices) are discussed.

Effect of boiler operation and RDF feedstock on emissions of dioxins and furans from an RDF fired sp reader-stoker system in Albany, NY

The data on dioxin and furan emissions revealed, based on individual analysis for 2,3,7,8-TCDD, TCDD, 2,3,7,8-TCDF and TCDF for the six test periods and the operation of the two RDF-fired boilers, that there is no apparent consistent relationship between the dioxin and furan emissions and the individual or combined (averaged) boiler steam flow, total flue gas flow, sidewall furnace temperature, furnace temperature at 2-second residence time, or total furnace residence time at this plant. Only RDF feeder balance begins to show a correlation. However, there was a difference between RDF-natural gas firing and RDF-only firing; the RDF-only firing had lower PCDD and PCDF emissions while consistently operating at lower excess air. The dioxin and furan emissions from this testing are comparable to the low end of the range of these emissions measured by the U.S. EPA at resource recovery plants in the past 4 years. This may be due in part to the calculated average furnace retention of 4 to 5 seconds during Tests #4–6, with average furnace temperatures at 2-second residence time from 1650°F to 1750°F. However, there was no correlation between dioxin and furan emissions in the stack and individual boiler operation, as judged by the average concentrations of O 2, CO, CO 2, 1-CO/CO 2), NO x, HCl, SO 2, or TSP, and furnace upset conditions versus normal operation as judged by instantaneous steam flow, sidewall furnace temperature, O 2, CO, NO x, or SO 2.

Parametric Mixed Integer Programming: An Application to Solid Waste Management

A method is developed for carrying out parametric analysis on a mixed integer linear program (MILP) as either objective function coefficients or right-hand-side values of the constraints are varied continuously. The method involves solving MILPs at point values of the parameters of variation and joining the results by LP parametric analysis. The procedure for parametric analysis on the objective function can be continued until a theoretical result proves that the analysis is complete. However, a heuristic rule that is presented may greatly reduce the number of individual MILPs that have to be solved and thus reduce the total computational effort. The rule assumes that if the same values of the integer variables are optimal at two different values of the change parameter, these same integer variable values will also be optimal at all intermediate parameter values. If the rule is applied, a complete parametric analysis requires solving 2n different MILPs, where n is the number of different sets of optimal integer variable values found. We determine the savings in number of MILPs solved using the heuristic rule compared to continuing the procedure to obtain theoretical proof of completeness. The paper also proposes various possible “advanced start” aids for solving the individual MILPs. Previously there has existed no method that could be used to perform continuous right-hand-side parametric analysis on an MILP of realistic size. A heuristic rule presented here makes possible such an analysis. The procedure again requires solving 2n different MILPs. The procedures for both objective function and right-hand-side analysis can be implemented using any software that can solve MILPs and perform LP parametric analysis. Computational results are reported using commercially available packages. The procedures are applied to a large fixed-charge model that was developed to analyze where to locate resource recovery plants in Southeastern Ontario. In that model it was essential to consider very wide variation in values of the parameters related to resource recovery. It was found that the results of the parametric analyses could be distilled into clear recommendations regarding which plants to build if a resource recovery policy is implemented.

Recovery by source separation: Industrial viewpoints

In dealing with the recycling of packaging materials, it is important that the issue is viewed in the right perspective and not isolated from the total context. Of special importance is the interlinking with traditional recycling activities and with planned mixed waste resource recovery plants. But first and foremost, the role of packaging as a means of effective distribution of goods with the inherent contribution to resource conservation should be recognized and taken into account. Because recycling practices as well as packaging design and use are all in a dynamic stage of development, the adoption of legislative and administrative measures that tend to freeze the status quo should be avoided in order that the benefits of these developments can be reaped at all levels.

The influence of color mixture on the use of glass cullet recovered from municipal solid waste

Glass can be recovered from municipal refuse as cullet for use in the manufacture of new glass containers. Among the four U.S. resource recovery plants designed for recovery of cullet, three will employ a froth flotation process and will produce a color-mixed cullet. Color-mixed cullet contains iron and chrome oxides used in coloring amber and green container glass. Limits to the use of color-mixed cullet are calculated based on reported concentrations of iron and chromium oxides in recovered cullet and on tolerances for these chemicals in container glass. The use of color-mixed cullet in flint (clear) container glass is limited primarily by the concentration of chromium oxide in the cullet. Approaches to expanding this limit and for monitoring chemical colorant levels in cullet are reviewed.

Resource recovery systems costs

The investment cost, operating cost and overall economics of resource recovery plants handling 500 to 2 000 tons per day of municipal solid waste were determined. These plants recover only refuse derived fuel and ferrous metal from the waste. Additional economics have been developed for plants recovering other products.