Economic and environmental benefits of natural treatment systems for sewage treatment: A life cycle perspective.

Sewage treatment involves a trade-off of land vs. energy and the location of installing Sewage Treatment Plants (STPs) strongly impacts the decisions regarding treatment technologies. In the wake of rapid urbanization, deteriorating freshwater quality and water scarcity, it is crucial to plan adequate and low-cost sewerage infrastructure that can improve the quality of life in rural and urban areas. The present work involves a novel life cycle analysis through six scenarios generated from a holistic perspective that can aid urban planners and urban local bodies in planning the sewage treatment facilities in their cities, towns or villages. Instead of planning sewerage infrastructure for a long-term period of thirty years, it is suggested to create and operate the STPs only for the upcoming decade. Further, owing to the drawbacks of mechanized and natural treatment systems, adopting a mix of these treatment approaches in planning infrastructure is suggested and the benefits of implementing the same are quantified and discussed. Implementing these strategies results in almost 30 % cost savings and 40 % reduction in greenhouse gas emissions, hence, investing in land for natural treatment systems is suggested instead of incurring heavy electricity bills for mechanized treatment systems. The land cost significantly affects the decision-making regarding treatment technology selection; hence, the variation in the life cycle cost of different sewage treatment approaches is assessed for varying land rates in India.

Cost-benefit analysis of rehabilitating old landfills: A case of Beiyangqiao landfill, Wuhan, China.

A comprehensive approach for evaluating the feasibility of landfill rehabilitation should be developed to allow landfill owners to thoroughly examine the feasibility of a landfill soil remediation project in advance. With a view of contributing to the development of a common framework for the evaluation of landfill rehabilitation projects, this paper presents the results of a case study in which the issue of assessing the costs and benefits of rehabilitating the Beiyangqiao simple landfill is addressed. Based on the results of a survey, the cost-benefit assessment criteria and candidate remediation methods were selected. The alternatives included are, in-situ landfill closure; in-situ aerobic stabilization combined with in-situ screening and classification of recovered materials, transport for off-site disposal; and ectopic mining combined with recycling and incineration. Results show that the costs of landfill rehabilitation would range from 11.23 to 32.02 million United States dollars (USD). The key benefits would be land reclamation, heat, or electricity generation by incineration, and recycling of waste materials. The total benefits would range in value from 59.62 to 61.47 million USD. The net present value of the three scenarios would be positive and would range from 8.6 to 10.02 million USD. The results suggest that all three scenarios were positive. Nevertheless, "in-situ aerobic stabilization, in-situ screening, transportation, and off-site disposal" was most beneficial considering all parameters.Implications: This study applied a cost-benefit analysis model for assessing the economic feasibility of landfill rehabilitation, which is important to promoting landfill rehabilitation, and the market potential was assessed based on an actual project. The findings can be useful for providing landfill owners choices in a landfill rehabilitation project to achieve least quantified costs and overhead.

Willingness to pay for higher construction waste landfill charge: A comparative study in Shenzhen and Qingdao, China.

High landfill charge presents an effective approach to divert construction waste from landfill. The stakeholders' willingness to pay (WTP) for the disposal of construction waste in landfill provide the useful information to set a reasonable charge level. Considering the diversity in stakeholder groups and regional socioeconomic conditions, contingent valuation method (CVM) was employed in this study to investigate the WTP of two major stakeholder groups in two typical Chinese cities. In addition, the perception of stakeholders towards landfill charge policy was measured and the impact of various factors on WTP was explored. The results indicated that there were statistically significant disparities of WTP between cities and stakeholder groups. Stakeholders from Shenzhen were willing to pay more than their counterparts in Qingdao. Contractors were willing to pay less than owners. Respondents who evaluate the policy as effective in reducing construction waste landfill were willing to pay more. However, firm size, ownership, position of respondent and perceived equity factors did not show statistically significant effect on WTP. These findings highlight the necessity to customize landfill charge policy according to local socioeconomic conditions.

Benchmarking the Energy Intensity of Small Water Resource Recovery Facilities.

To enable small communities to benchmark the energy efficiency of their water resource recovery facilities (also known as wastewater treatment facilities), multiple linear regression models of electric and overall energy intensity (kWh/m3) were created using data from Nebraska and Pennsylvania. Key variables found to be significant include: facility type, supplemental energy usage for sludge treatment, average flow, percent design flow, climate controlled floor area, effluent NH3-N, and influent CBOD5. The results show that energy use models for small systems differ from those for large facilities and that regulatory changes can affect energy usage. Step changes in the data for facilities that changed operators highlight the importance of operational decisions on energy efficiency for small facilities serving fewer than 10,000 people. Differences were observed between the models of data from specific states. Although these models may not include all factors that account for variability in energy use, they can provide a reference benchmark for small WRRFs.

Simple and practical on-site treatment of high microcystin levels in water using polypropylene plastic.

Microcystin (MC) is a hepatotoxin produced by various cyanobacteria during harmful algal blooms (HAB's) in freshwater environments. Advanced treatment methods can remove MC from drinking water, but are costly and do not address recreational water exposure and ecosystem health concerns. Here we investigate the feasibility of utilizing plastics as a MC-adsorbing material, for use in water resources used for recreation, agriculture, aquaculture and drinking water. Water containing 20 µg/L MC-LR was exposed to polypropylene (PP) plastic for a six-day period at varying temperatures (22, 37, 65°C). Water samples were then collected at 0, 1, 2, and 6 hour-intervals to examine short term treatment feasibility. Samples were also taken at 24 hours, 3 days, and 6 days to determine long-term treatment effectiveness. MC concentrations were analyzed using ELISA. Results showed a maximal reduction of nearly 70% of MC-LR after a 6-day treatment with PP at 65°C. Temperature enhanced MC-LR reduction over a 6-day period: 70% reduction at 65°C; 50% at 37°C; 38% at 22°C. We propose an inexpensive intervention strategy which can be deployed rapidly on-site in various source waters, including in resource-limited settings. During the high peak of HAB season, the strategy can be applied in source waters, alleviating water treatment burden for treatment plants, lowering treatment costs and reducing chemical usage.

How to make a large nutrient removal plant energy self-sufficient. Latest upgrade of the Vienna Main Wastewater Treatment Plant (VMWWTP).

The goal of making nutrient removal wastewater treatment energy self-sufficient or even energy producing has become a worldwide accepted goal of technology development. The latest upgrade of the Vienna Main Wastewater Treatment Plant (VMWWTP) with a design capacity of 4 million (M) population equivalent (PE) will produce about 20% more energy on a yearly basis than needed for operation due to a special process scheme. It consists of primary sedimentation, a special 2-stage activated sludge (AS) process configuration where excess sludge is only withdrawn from the first stage AS plant. Raw sludge is subject to mechanical thickening to ∼8% digested sludge (DS) for digestion at high solids concentration. The reject water after nitritation is used for denitritation in the first stage AS plant. This results in markedly reducing the energy requirement for aeration. The design of this last upgrade for energy optimization of sludge treatment is based on the long-term full-scale data from the existing plant, results of mid-term pilot investigations, sound theoretical mass balance calculations and an adapted dynamic model development. All this is presented in this paper. The full-scale upgrade is under construction and will start operating in 2020.

Benchmarking of energy consumption in municipal wastewater treatment plants - a survey of over 200 plants in Italy.

One of the largest surveys in Europe about energy consumption in Italian wastewater treatment plants (WWTPs) is presented, based on 241 WWTPs and a total population equivalent (PE) of more than 9,000,000 PE. The study contributes towards standardised resilient data and benchmarking and to identify potentials for energy savings. In the energy benchmark, three indicators were used: specific energy consumption expressed per population equivalents (kWh PE-1 year-1), per cubic meter (kWh/m3), and per unit of chemical oxygen demand (COD) removed (kWh/kgCOD). The indicator kWh/m3, even though widely applied, resulted in a biased benchmark, because highly influenced by stormwater and infiltrations. Plants with combined networks (often used in Europe) showed an apparent better energy performance. Conversely, the indicator kWh PE-1 year-1 resulted in a more meaningful definition of a benchmark. High energy efficiency was associated with: (i) large capacity of the plant, (ii) higher COD concentration in wastewater, (iii) separate sewer systems, (iv) capacity utilisation over 80%, and (v) high organic loads, but without overloading. The 25th percentile was proposed as a benchmark for four size classes: 23 kWh PE-1 y-1 for large plants > 100,000 PE; 42 kWh PE-1 y-1 for capacity 10,000 < PE < 100,000, 48 kWh PE-1 y-1 for capacity 2,000 < PE < 10,000 and 76 kWh PE-1 y-1 for small plants < 2,000 PE.

Operating room waste: disposable supply utilization in neurointerventional procedures.

BACKGROUND: Operating rooms account for 70% of hospital waste, increasing healthcare costs and creating environmental hazards. Endovascular treatment of cerebrovascular pathologies has become prominent, and associated products highly impact the total cost of care. We investigated the costs of endovascular surgical waste at our institution. METHODS: Data from 53 consecutive endovascular procedures at the Radboud UMC Nijmegen from May to December 2016 were collected. "Unused disposable supply" was defined as one-time use items opened but not used during the procedure. Two observers cataloged the unused disposable supply for each case. The cost of each item was determined from the center supply catalog, and these costs were summed to determine the total cost of unused supply per case. RESULTS: Thirteen diagnostic cerebral digital subtraction angiographies (DSA) (24.5%) and 40 endovascular procedures (75.5%) were analyzed. Total interventional waste was 27,299.53 € (mean 515.09 € per procedure). While total costs of unused disposable supply were almost irrelevant for DSAs, they were consistent for interventional procedures (mean 676.49 € per case). Aneurysm standard coiling had the highest impact on total interventional waste (mean 1061.55 €). Disposable interventional products had a very high impact on the surgical waste costs in the series of the neurointerventional procedures (95% of total waste). CONCLUSIONS: This study shows the impact of neurointerventional waste on the total care costs for cerebrovascular patients. This might reflect the tendency to anticipate needs and emergencies in neurointervention. Responsible use of disposable material can be achieved by educating operators and nurses and creating operator preference cards.

Modelling energy costs for different operational strategies of a large water resource recovery facility.

The main objective of this paper is to demonstrate the importance of applying dynamic modelling and real energy prices on a full scale water resource recovery facility (WRRF) for the evaluation of control strategies in terms of energy costs with aeration. The Activated Sludge Model No. 1 (ASM1) was coupled with real energy pricing and a power consumption model and applied as a dynamic simulation case study. The model calibration is based on the STOWA protocol. The case study investigates the importance of providing real energy pricing comparing (i) real energy pricing, (ii) weighted arithmetic mean energy pricing and (iii) arithmetic mean energy pricing. The operational strategies evaluated were (i) old versus new air diffusers, (ii) different DO set-points and (iii) implementation of a carbon removal controller based on nitrate sensor readings. The application in a full scale WRRF of the ASM1 model coupled with real energy costs was successful. Dynamic modelling with real energy pricing instead of constant energy pricing enables the wastewater utility to optimize energy consumption according to the real energy price structure. Specific energy cost allows the identification of time periods with potential for linking WRRF with the electric grid to optimize the treatment costs, satisfying operational goals.

Distributed mixed-integer fuzzy hierarchical programming for municipal solid waste management. Part II: scheme analysis and mechanism revelation.

As presented in the first companion paper, distributed mixed-integer fuzzy hierarchical programming (DMIFHP) was developed for municipal solid waste management (MSWM) under complexities of heterogeneities, hierarchy, discreteness, and interactions. Beijing was selected as a representative case. This paper focuses on presenting the obtained schemes and the revealed mechanisms of the Beijing MSWM system. The optimal MSWM schemes for Beijing under various solid waste treatment policies and their differences are deliberated. The impacts of facility expansion, hierarchy, and spatial heterogeneities and potential extensions of DMIFHP are also discussed. A few of findings are revealed from the results and a series of comparisons and analyses. For instance, DMIFHP is capable of robustly reflecting these complexities in MSWM systems, especially for Beijing. The optimal MSWM schemes are of fragmented patterns due to the dominant role of the proximity principle in allocating solid waste treatment resources, and they are closely related to regulated ratios of landfilling, incineration, and composting. Communities without significant differences among distances to different types of treatment facilities are more sensitive to these ratios than others. The complexities of hierarchy and heterogeneities pose significant impacts on MSWM practices. Spatial dislocation of MSW generation rates and facility capacities caused by unreasonable planning in the past may result in insufficient utilization of treatment capacities under substantial influences of transportation costs. The problems of unreasonable MSWM planning, e.g., severe imbalance among different technologies and complete vacancy of ten facilities, should be gained deliberation of the public and the municipal or local governments in Beijing. These findings are helpful for gaining insights into MSWM systems under these complexities, mitigating key challenges in the planning of these systems, improving the related management practices, and eliminating potential socio-economic and eco-environmental issues resulting from unreasonable management.

Material flow-based economic assessment of landfill mining processes.

This paper provides an economic assessment of alternative processes for landfill mining compared to landfill aftercare with the goal of assisting landfill operators with the decision to choose between the two alternatives. A material flow-based assessment approach is developed and applied to a landfill in Germany. In addition to landfill aftercare, six alternative landfill mining processes are considered. These range from simple approaches where most of the material is incinerated or landfilled again to sophisticated technology combinations that allow for recovering highly differentiated products such as metals, plastics, glass, recycling sand, and gravel. For the alternatives, the net present value of all relevant cash flows associated with plant installation and operation, supply, recycling, and disposal of material flows, recovery of land and landfill airspace, as well as landfill closure and aftercare is computed with an extensive sensitivity analyses. The economic performance of landfill mining processes is found to be significantly influenced by the prices of thermal treatment (waste incineration as well as refuse-derived fuels incineration plant) and recovered land or airspace. The results indicate that the simple process alternatives have the highest economic potential, which contradicts the aim of recovering most of the resources.

Quantitative option analysis for implementation and management of landfills.

The selection of the most feasible strategy for implementation of landfills is a challenging step. Potential implementation options of landfills cover a wide range, from conventional construction contracts to the concessions. Montenegro, seeking to improve the efficiency of the public services while maintaining affordability, was considering privatisation as a way to reduce public spending on service provision. In this study, to determine the most feasible model for construction and operation of a regional landfill, a quantitative risk analysis was implemented with four steps: (i) development of a global risk matrix; (ii) assignment of qualitative probabilities of occurrences and magnitude of impacts; (iii) determination of the risks to be mitigated, monitored, controlled or ignored; (iv) reduction of the main risk elements; and (v) incorporation of quantitative estimates of probability of occurrence and expected impact for each risk element in the reduced risk matrix. The evaluated scenarios were: (i) construction and operation of the regional landfill by the public sector; (ii) construction and operation of the landfill by private sector and transfer of the ownership to the public sector after a pre-defined period; and (iii) operation of the landfill by the private sector, without ownership. The quantitative risk assessment concluded that introduction of a public private partnership is not the most feasible option, unlike the common belief in several public institutions in developing countries. A management contract for the first years of operation was advised to be implemented, after which, a long term operating contract may follow.

A robust and cost-effective integrated process for nitrogen and bio-refractory organics removal from landfill leachate via short-cut nitrification, anaerobic ammonium oxidation in tandem with electrochemical oxidation.

A cost-effective process, consisting of a denitrifying upflow anaerobic sludge blanket (UASB), an oxygen-limited anoxic/aerobic (A/O) process for short-cut nitrification, and an anaerobic reactor (ANR) for anaerobic ammonia oxidation (anammox), followed by an electrochemical oxidation process with a Ti-based SnO2-Sb2O5 anode, was developed to remove organics and nitrogen in a sewage diluted leachate. The final chemical oxygen demand (COD), ammonia nitrogen (NH4(+)-N) and total nitrogen (TN) of 70, 11.3 and 39 (all in mg/L), respectively, were obtained. TN removal in UASB, A/O and ANR were 24.6%, 49.6% and 16.1%, respectively. According to the water quality and molecular biology analysis, a high degree of anammox besides short-cut nitrification and denitrification occurred in A/O. Counting for 16.1% of TN removal in ANR, at least 43.2-49% of TN was removed via anammox. The anammox bacteria in A/O and ANR, were in respective titers of (2.5-5.9)×10(9) and 2.01×10(10)copy numbers/(gSS).

Assessment of economic instruments for countries with low municipal waste management performance: An approach based on the analytic hierarchy process.

Economic instruments provide significant potential for countries with low municipal waste management performance in decreasing landfill rates and increasing recycling rates for municipal waste. In this research, strengths and weaknesses of landfill tax, pay-as-you-throw charging systems, deposit-refund systems and extended producer responsibility schemes are compared, focusing on conditions in countries with low waste management performance. In order to prioritise instruments for implementation in these countries, the analytic hierarchy process is applied using results of a literature review as input for the comparison. The assessment reveals that pay-as-you-throw is the most preferable instrument when utility-related criteria are regarded (wb = 0.35; analytic hierarchy process distributive mode; absolute comparison) mainly owing to its waste prevention effect, closely followed by landfill tax (wb = 0.32). Deposit-refund systems (wb = 0.17) and extended producer responsibility (wb = 0.16) rank third and fourth, with marginal differences owing to their similar nature. When cost-related criteria are additionally included in the comparison, landfill tax seems to provide the highest utility-cost ratio. Data from literature concerning cost (contrary to utility-related criteria) is currently not sufficiently available for a robust ranking according to the utility-cost ratio. In general, the analytic hierarchy process is seen as a suitable method for assessing economic instruments in waste management. Independent from the chosen analytic hierarchy process mode, results provide valuable indications for policy-makers on the application of economic instruments, as well as on their specific strengths and weaknesses. Nevertheless, the instruments need to be put in the country-specific context along with the results of this analytic hierarchy process application before practical decisions are made.

GIS-based approach for optimised collection of household waste in Mostaganem city (Western Algeria).

This work proposes an optimisation of municipal solid waste collection in terms of collection cost and polluting emissions (carbon oxides, carbon dioxides, nitrogen oxides and particulate matter). This method is based on a simultaneous optimisation of the vehicles routing (distance and time travelled) and the routing system for household wastes collection based on the existing network of containers, the capacity of vehicles and the quantities generated in every collecting point. The process of vehicle routing optimisation involves a geographical information system. This optimisation has enabled a reduction of travelled distances, collection time, fuel consumption and polluting emissions. Pertinent parameters affecting the fuel consumption have been utilised, such as the state of the road, the vehicles speed in the different paths, the vehicles load and collection frequencies. Several scenarios have been proposed. The results show the importance of the construction of a waste transfer station that can reduce the cost of household waste collection and emissions of waste transfer pollutants. Among the proposed five scenarios, we have noticed that the fourth scenario (by constructing a waste transfer centre) was the most performing. So, the routes of optimised travelled distance of the new circuits have been reduced by 71.81%. The fuel consumption has been reduced by 72.05% and the total cost of the collection has been reduced by 46.8%. For the polluting emissions, the reduction has been by 60.2% for carbon oxides, by 67.9% for carbon dioxides, by 74.2% for nitrogen oxides and by 65% for particulate matter.

Landfill mining: Development of a cost simulation model.

Landfill mining permits recovering secondary raw materials from landfills. Whether this purpose is economically feasible, however, is a matter of various aspects. One is the amount of recoverable secondary raw material (like metals) that can be exploited with a profit. Other influences are the costs for excavation, for processing the waste at the landfill site and for paying charges on the secondary disposal of waste. Depending on the objectives of a landfill mining project (like the recovery of a ferrous and/or a calorific fraction) these expenses and revenues are difficult to assess in advance. This situation complicates any previous assessment of the economic feasibility and is the reason why many landfills that might be suitable for landfill mining are continuingly operated as active landfills, generating aftercare costs and leaving potential hazards to later generations. This article presents a newly developed simulation model for landfill mining projects. It permits identifying the quantities and qualities of output flows that can be recovered by mining and by mobile on-site processing of the waste based on treatment equipment selected by the landfill operator. Thus, charges for disposal and expected revenues from secondary raw materials can be assessed. Furthermore, investment, personnel, operation, servicing and insurance costs are assessed and displayed, based on the selected mobile processing procedure and its throughput, among other things. For clarity, the simulation model is described in this article using the example of a real Austrian sanitary landfill.

Monetizing the social benefits of landfill mining: Evidence from a Contingent Valuation survey in a rural area in Greece.

Despite the emerging global attention towards promoting waste management policies that reduce environmental impacts and conserve natural resources, landfilling still remains the dominant waste management practice in many parts of the world. Owing to this situation, environmental burdens are bequeathed to and large amounts of potentially valuable materials are lost for future generations. As a means to undo these adverse effects a process known as landfill mining (LFM) could be implemented provided that economic feasibility is ensured. So far, only a few studies have focused on the economic feasibility of LFM from a private point of view and even less studies have attempted to economically justify the need for LMF projects from a social point of view. This paper, aiming to add to the limited literature in the field, presents the results of a survey conducted in a rural district in Greece, by means of the Contingent Valuation method (CVM) in order to estimate society's willingness to pay for LFM programs. According to the empirical survey, more than 95% of the respondents recognize the need for LFM programs. Nevertheless, only one-fourth of the respondents are willing to pay through increased taxes for LFM, owing mainly to economic depression and unemployment. Those who accept the increased tax are willing to pay about €50 per household per year, on average, which results in a mean willingness to pay (WTP) for the entire population under investigation of around €12 per household per year. The findings of this research work provide useful insights about the 'dollar-based' benefits of LFM in the context of social cost-benefit analysis of LFM projects. Yet, it is evident that further research is necessary.

Implications of variable waste placement conditions for MSW landfills.

This investigation was conducted to evaluate the influence of waste placement practices on the engineering response of municipal solid waste (MSW) landfills. Waste placement conditions were varied by moisture addition to the wastes at the time of disposal. Tests were conducted at a California landfill in test plots (residential component of incoming wastes) and full-scale active face (all incoming wastes including residential, commercial, and self-delivered components). The short-term effects of moisture addition were assessed by investigating compaction characteristics and moisture distribution and the long-term effects by estimating settlement characteristics of the variably placed wastes. In addition, effects on engineering properties including hydraulic conductivity and shear strength, as well as economic aspects were investigated. The unit weight of the wastes increased with moisture addition to a maximum value and then decreased with further moisture addition. At the optimum moisture conditions, 68% more waste could be placed in the same landfill volume compared to the baseline conditions. Moisture addition raised the volumetric moisture content of the wastes to the range 33-42%, consistent with values at and above field capacity. Moisture transfer occurred between consecutive layers of compacted wastes and a moisture addition schedule of 2 days of as-received conditions and 1 day of moisture addition was recommended. Settlement of wastes was estimated to increase with moisture addition, with a 34% increase at optimum moisture compared to as-received conditions. Overall, moisture addition during compaction increased unit weight, the amount of incoming wastes disposed in a given landfill volume, biological activity potential, and predicted settlement. The combined effects have significant environmental and economic implications for landfill operations.