Municipal Waste Treatment System Research Articles

Development of Solid Municipal Waste Treatment System within Circular Economy Framework

Development of Solid Municipal Waste Treatment System within Circular Economy Framework

A Fuzzy Multi-Criteria Model for Municipal Waste Treatment Systems Evaluation including Energy Recovery

One of the recent problems on waste sorting systems is their performance evaluation for proper decision making and management. For this purpose, multi-criteria methods can be used to evaluate the sorting system from both operational and financial perspectives. According to a recent literature review, there are no solutions for evaluating waste sorting systems that take into account: sorting point utilisation, sorting efficiency, waste stream irregularity, and technical system availability. In addition, the problem of data uncertainty and the need to use expert judgements indicate the need for the implementation of methods adjusted to the qualitative and quantitative assessment, such as the fuzzy approach. Following this, in order to overcome the presented limitations, the authors introduced the new assessment method for waste sorting systems based on multi-criteria model implementation and fuzzy theory use. Therefore, the developed model was based on a hierarchical fuzzy logic model for which appropriate membership function parameters and inference rules were defined. The specificity of the chosen assessment criteria and their justification was provided. The model has been implemented to evaluate one of the waste sorting plants in Wroclaw, Poland. Tests have been conducted for seven different configurations of waste sorting lines (with variable input parameters). The study focuses on analysing the amount of selected waste at each station in relation to the total stream size of each fraction. Efficiency was measured by the mass of the collected waste and the number of pieces of waste in each fraction. Based on the obtained results, estimations of particular parameters of the model were made, and the results were presented and commented on. It was shown that there is a significant relationship between the level of system evaluation and sorting efficiency and an inverse relationship with the level of RDF obtained. The analysis was based on Pearson’s linear correlation coefficient estimation and linear regression implementation.

Employment Effects of Different Municipal Waste Treatment Systems Based on Data from Austria

Although waste management has long been an important economic sector, its employment effects have so far been neglected in economic calculations. Recently, employment effects have been addressed in the European Green Deal or the Climate Neutrality Strategy. A scientific calculation is, however, still missing. To close this gap, our paper develops a set of alternative models as to residual waste treatment and investigates their potential to produce direct employment effects. The models include employment required for treatment plants plus employees needed in collection and transports. The models range from basic to sophisticated, from unregulated landfilling via 100 % waste incineration to mechanical-biological treatment to improved separate collection and advanced recycling. Data for devising these models were derived from a secondary analysis (e.g. residual waste analyses of the Austrian provinces) and from expert interviews. Although the models are simplified and build on generic waste management systems, they allow for a rough estimation of employment effects: The more sophisticated the waste management system, the more employees are necessary. In all models, but especially in improved separate collection, collection accounts for a significant part of the additional employment. The models show an increase in employment many times over with the improved separate collection model compared to the other models. Although our results can only be scaled up to European Union level in a limited way, we can state that shifting from less sophisticated waste management models to more desirable ones can involve an increase in employment of at least some 40.000 jobs.

Growth and fatty acid characterization of microalgae isolated from municipal waste-treatment systems and the potential role of algal-associated bacteria in feedstock production.

Much research has focused on growing microalgae for biofuel feedstock, yet there remain concerns about the feasibility of freshwater feedstock systems. To reduce cost and improve environmental sustainability, an ideal microalgal feedstock system would be fed by municipal, agricultural or industrial wastewater as a main source of water and nutrients. Nonetheless, the microalgae must also be tolerant of fluctuating wastewater quality, while still producing adequate biomass and lipid yields. To address this problem, our study focused on isolating and characterizing microalgal strains from three municipal wastewater treatment systems (two activated sludge and one aerated-stabilization basin systems) for their potential use in biofuel feedstock production. Most of the 19 isolates from wastewater grew faster than two culture collection strains under mixotrophic conditions, particularly with glucose. The fastest growing wastewater strains included the genera Chlorella and Dictyochloris. The fastest growing microalgal strains were not necessarily the best lipid producers. Under photoautotrophic and mixotrophic growth conditions, single strains of Chlorella and Scenedesmus each produced the highest lipid yields, including those most relevant to biodiesel production. A comparison of axenic and non-axenic versions of wastewater strains showed a notable effect of commensal bacteria on fatty acid composition. Strains grown with bacteria tended to produce relatively equal proportions of saturated and unsaturated fatty acids, which is an ideal lipid blend for biodiesel production. These results not only show the potential for using microalgae isolated from wastewater for growth in wastewater-fed feedstock systems, but also the important role that commensal bacteria may have in impacting the fatty acid profiles of microalgal feedstock.

Multi-criteria selection of municipal waste treatment system using VIKOR method

The main goal is determination of municipal waste treatment system. System alternatives include recycling, composting, incineration, and landfilling. Criteria are derived from environmental protection, efficiency, financial, and social effects. This decision problem is characterised by non-commensurable and competing (conflicting) criteria, with no solution satisfying all criteria simultaneously. The multi-criteria decision making method VIKOR is applied for ranking alternatives of waste treatment and selecting compromise solution from the set of feasible alternatives. The method compromises conflicting criteria, and group utility with individual regret. Multi-criteria decision making for municipal solid waste management in the region of Novi Sad, Serbia, is presented as an example, illustrating alternatives generation, formulation of criteria functions, evaluation of alternatives in terms of criteria, application of the VIKOR method and the proposition of final solution. Selected treatment system consists of mechanical-biological treatment (MBT) plant, incineration in cement kiln, sanitary landfill, and market for recycling material.

Multi-criteria selection of municipal waste treatment system using VIKOR method

Multi-criteria selection of municipal waste treatment system using VIKOR method

Fate of metals contained in waste electrical and electronic equipment in a municipal waste treatment process

In Japan, waste electrical and electronic equipment (WEEE) that is not covered by the recycling laws are treated as municipal solid waste. A part of common metals are recovered during the treatment; however, other metals are rarely recovered and their destinations are not clear. This study investigated the distribution ratios and substance flows of 55 metals contained in WEEE during municipal waste treatment using shredding and separation techniques at a Japanese municipal waste treatment plant. The results revealed that more than half of Cu and most of Al contained in WEEE end up in landfills or dissipate under the current municipal waste treatment system. Among the other metals contained in WEEE, at least 70% of the mass was distributed to the small-grain fraction through the shredding and separation and is to be landfilled. Most kinds of metals were concentrated several fold in the small-grain fraction through the process and therefore the small-grain fraction may be a next target for recovery of metals in terms of both metal content and amount. Separate collection and pre-sorting of small digital products can work as effective way for reducing precious metals and less common metals to be landfilled to some extent; however, much of the total masses of those metals would still end up in landfills and it is also important to consider how to recover and utilize metals contained in other WEEE such as audio/video equipment.

Optimal Design of Waste-Water Treatment System

A municipal waste treatment system is provided to achieve the desired degree of nutrients removal prior to its disposal on land or a receiving body of water. The conventional method of designing a waste-water treatment system unit-wise, seldom yields an economical design. A single cost function of the system subjected to behavioural and cost constraints represents a statement to which various known methodologies of systems engineering could be applied to achieve economical design of the overall treatment scheme. This paper presents the application of Univariate method of nonlinear minimization on a waste-water treatment system employing activated sludge process.It is recommended that to achieve the minimum cost of the system, suspended solids removal efficiency in primary settlers be taken as 13 percent, the activated sludge system may be loaded with more BOD to keep F/M ratio 5, and the excess sludge to be digested be thickened to about 6 percent solids concentration. The use of this algorithm has resulted in savings of 20 percent to 28 percent in capitalised cost of the system for F/M ratios of 0.4 and 0.5 respect1ve1y.

Effluent for Irrigation — A Need for Caution?a

ABSTRACTMost municipal waste treatment systems receive, treat, and eventually discard to some segment of the environment storm runoff and liquid wastes from all industrial, commercial, and domestic areas and establishments in the community. At any given time these wastes may contain viruses, antibiotics, hormones, nutrients, weedkillers, fungicides, pesticides, trace metals, and an almost countless number of toxic chemical compounds. Present treatment by the old, ineffectual sewage treatment methods and facilities still employed generally does not remove nor reduce to a harmless state all of the hazardous materials contained in the waste streams entering the plant. Some are more concentrated when they leave the plant in effluent and sludge than they were upon entry.Existing pollution protection laws prohibit surface‐water dilution of these effluents and sludges. Drying, burning, or distilling them is very costly, causes air pollution, and produces potentially hazardous chemical residues which still must be disposed of in some nonpolluting fashion. There are no “technologically feasible, economically reasonable” alternative methods of effectively treating these wastes to an acceptable quality level for discharge to streams. For these reasons, land disposal of sewage effluent and sludges now is being widely promoted and employed as the best available method of treatment.It is estimated that as many as 300 municipalities have gone to the land to solve their sewage plant waste problems in recent months. Many of these have been at least partially funded with State and Federal grants. If similar permits and financial assistance continue to be granted in the future, it is anticipated that several thousand municipalities will follow suit within the next few years.