Recovery of coagulant from water supply plant sludge and its effect on clarification

Spent coagulant in water supply plant sludge was extracted with H₂SO₄ and the efficiency of the reused coagulant was studied. The optimum pH values for coagulant extraction and clarification with the reused coagulant were 3.0–4.0 and about 6, respectively. In treating raw influent obtained from a sewage treatment plant and wastewater from a coastal landfill site, the removal of chemical oxygen demand (COD), total nitrogen, and total phosphorous with the recovered coagulant was higher than that with commercial aluminum sulfate or polyaluminum chloride. In addition, the sludge settling properties, the extra sludge mass formation, the supernatant quality, and the cost of reagents were also studied. The coagulant recovered from water supply plant sludge by H₂SO₄ extraction could be successfully reused for the clarification of domestic and food industry wastewaters.     

Development of a site‐specific cleanup goal for PAHs in soil based on anthropogenic background levels

During removal of an industrial landfill in Folsom, California, fill material was excavated and processed through a mechanical screening plant to segregate soil from construction and demolition debris. The segregated soil was stockpiled and analyzed for a wide range of chemical groups to determine if the soil could be backfilled on‐site. The analytical results indicated many of the stockpiles had concentrations of polycyclic aromatic hydrocarbons (PAHs) that exceeded US EPA Regional Screening Levels, and a large quantity of soil was initially classified as requiring off‐site disposal at considerable cost. Because PAHs are ubiquitous in urban settings and the landfill did not contain a significant source of PAHs, development of a site‐specific PAH cleanup goal was proposed to regulators. Cal/EPA guidance for using on‐site data to develop a background threshold for metals was applied to the development of the PAH cleanup goal. The Cal/EPA approach involves demonstrating whether the data belong to a single population or multiple populations based on data distribution tests and probability plots. This article explains the statistical and graphical methods that were used to demonstrate that the Cal/EPA approach was valid for PAHs and that the calculated cleanup level was consistent with published anthropogenic background levels of PAHs in California and across the United States. The site‐specific PAH cleanup goal enabled most of the soil to be backfilled on‐site, saving about $227,000 in transportation and disposal costs, and regulators subsequently approved unrestricted future use of the property. © 2010 Wiley Periodicals, Inc.     

Economic aspects of the rehabilitation of the Hiriya landfill

The Hiriya landfill, Israel's largest, operated from 1952 to 1998. The landfill, located in the heart of the Dan Region, developed over the years into a major landscape nuisance and environmental hazard. In 1998, the Israeli government decided to close the landfill, and in 2001 rehabilitation activities began at the site, including site investigations, engineering and scientific evaluations, and end-use planning. The purpose of the present research is to perform a cost-benefit analysis of engineering and architectural-landscape rehabilitation projects considered for the site. An engineering rehabilitation project is required for the reduction of environmental impacts such as greenhouse gas emissions, slope instability and leachate formation. An architectural-landscape rehabilitation project would consider improvements to the site to make it suitable for future end uses such as a public park. The findings reveal that reclamation is worthwhile only in the case of architectural-landscape rehabilitation of the landfill, converting it into a public park. Engineering rehabilitation alone was found to be unjustified, but is essential to enable the development of a public park.     

Case study of landfill reclamation at a Florida landfill site

A landfill reclamation project was considered to recover landfill airspace and soil, reduce future groundwater impacts by removing the waste buried in the unlined area, and optimize airspace use at the site. A phased approach was utilized to evaluate the technical and economic feasibility of the reclamation project; based on the results of these evaluations, approximately 6.8 ha of the unlined cells were reclaimed. Approximately 371,000 in-place cubic meters of waste was mined from 6.8 ha in this project. Approximately 230,600 cubic meters of net airspace was recovered due to beneficial use of the recovered final cover soil and reclaimed soil as intermediate and daily cover soil, respectively, for the current landfill operations. This paper presents the researchers’ landfill reclamation project experience, including a summary of activities pertaining to reclamation operations, an estimation of reclamation rates achieved during the project, project costs and benefits, and estimated composition of the reclaimed materials.     

Bio-tarp alternative daily cover prototypes for methane oxidation atop open landfill cells

Final landfill covers are highly engineered to prevent methane release into the atmosphere. However, methane production begins soon after waste placement and is an unaddressed source of emissions. The methane oxidation capacity of methanotrophs embedded in a “bio-tarp” was investigated as a means to mitigate methane release from open landfill cells. The bio-tarp would also serve as an alternative daily cover during routine landfill operation.Evaluations of nine synthetic geotextiles identified two that would likely be suitable bio-tarp components. Pilot tarp prototypes were tested in continuous flow systems simulating landfill gas conditions. Multilayered bio-tarp prototypes consisting of alternating layers of the two geotextiles were found to remove 16% of the methane flowing through the bio-tarp. The addition of landfill cover soil, compost, or shale amendments to the bio-tarp increased the methane removal up to 32%. With evidence of methane removal in a laboratory bioreactor, prototypes were evaluated at a local landfill using flux chambers installed atop intermediate cover at a landfill. The multilayered bio-tarp and amended bio-tarp configurations were all found to decrease landfill methane flux; however, the performance efficacy of bio-tarps was not significantly different from controls without methanotrophs. Because highly variable methane fluxes at the field site likely confounded the test results, repeat field testing is recommended under more controlled flux conditions.     

Expediting sustainable brownfields redevelopment by applying Triad using the membrane interface probe

Redevelopment and reuse plans are often based upon an expedited delineation and remediation life cycle, since delayed reuse usually has economic consequences. It has also become increasingly important to utilize sustainable practices to achieve investigation and remediation goals. In this article, the Triad approach is used to expedite the delineation of a source area within a municipal landfill to complete the remedial effort prior to construction of an urban civic center. The Triad approach uses the three elements of systematic project planning, dynamic work strategy, and real‐time measurement to expedite site characterization (Interstate Technology and Regulatory Council, 2003). In this article, the Triad sampling strategy consisted of two phases. The first phase included in situ screening of soil and groundwater using the membrane interface probe (MIP), and the second phase included confirmatory sampling via vertical profiles in the soil and groundwater. This study found that, using the MIP in a dynamic sampling strategy, a critical element of the Triad approach, combined with the proper placement of confirmatory samples, significantly reduced overall project cost and will expedite the site redevelopment. The use of the Triad approach also contributed to the integration of green and sustainable practices into the project. © 2010 Wiley Periodicals, Inc.     

Consensus Oriented Public Relations As A Solution To The Landfill Conflict

The siting of landfills usually meets with the disapproval of residents living in the immediate proximity of potential landfill sites and frequently arouses public protest. Also in Austria, the public's readiness to safeguard their interests has been increasing, thus such conflicts can no longer be avoided. This fact raises the question among future landfill operators, as to how to react in such cases, and how a thus sensitized public can be dealt with. Seen from the viewpoint of communication, landfill operators must direct more attention to public relations.Within a research project at the University of Vienna, we have developed a public relations model which is intended to support a consensus between the landfill operators and the residents immediately affected by the operators' activities. The results prove that the so called "consensus-oriented public relations" approach is principally right. That is, those people who, due to our survey in the communities, could envisage a landfill site being installed, broadly agreed with the landfill operator on the levels of understanding provided by the model.     

Overview on LFG projects in China

Since the first landfill gas (LFG) power plant in China was built in 1998, by now more than 10 years have passed. In this period the LFG utilization process has progressed greatly in China. An overall review of the process is presented in this paper, which includes the background of policies, the information about the approval procedure of LFG projects, and the theoretical methods used to estimate the amount of LFG’s generation. Detailed analysis on the project practice, such as LFG collection techniques, LFG utilization condition in China, is made. According to statistic data, before the end of 2008, 26 LFG power projects have been built and put into operation with total power capacity around 56.8 MW, and 2.234 million tons of carbon dioxide equivalent abatement has been achieved annually by all of these LFG projects. The future of LFG industry in China is expected that there is still considerable developing space for LFG utilization in the near coming years, however after 2012, the progress speed may slow down because of some adverse aspects, such as available landfill resource becomes scarce, new laws implemented in China might exclude Chinese landfills from future CDM activities, etc.     

Knowledge based ranking algorithm for comparative assessment of post-closure care needs of closed landfills

Post-closure care (PCC) activities at landfills include cap maintenance; water quality monitoring; maintenance and monitoring of the gas collection/control system, leachate collection system, groundwater monitoring wells, and surface water management system; and general site maintenance. The objective of this study was to develop an integrated data and knowledge based decision making tool for preliminary estimation of PCC needs at closed landfills. To develop the decision making tool, 11 categories of parameters were identified as critical areas which could affect future PCC needs. Each category was further analyzed by detailed questions which could be answered with limited data and knowledge about the site, its history, location, and site specific characteristics. Depending on the existing knowledge base, a score was assigned to each question (on a scale 1-10, as 1 being the best and 10 being the worst). Each category was also assigned a weight based on its relative importance on the site conditions and PCC needs. The overall landfill score was obtained from the total weighted sum attained. Based on the overall score, landfill conditions could be categorized as critical, acceptable, or good. Critical condition indicates that the landfill may be a threat to the human health and the environment and necessary steps should be taken. Acceptable condition indicates that the landfill is currently stable and the monitoring should be continued. Good condition indicates that the landfill is stable and the monitoring activities can be reduced in the future. The knowledge base algorithm was applied to two case study landfills for preliminary assessment of PCC performance.     

Application of source removal and natural attenuation remediation strategies at MGP sites in Wisconsin

This article presents site closure strategies of source material removal and dissolved‐phase groundwater natural attenuation that were applied at two manufactured gas plant (MGP) sites in Wisconsin. The source removal actions were implemented in 1999 and 2000 with groundwater monitoring activities preceding and following those actions. Both of these sites have unique geological and hydrogeological conditions. The article briefly presents site background information and source removal activities at both of these sites and focuses on groundwater analytical testing data that demonstrate remediation of dissolved‐phase MGP‐related groundwater impacts by natural attenuation. A statistical evaluation of the data supports a stable or declining MGP parameter concentration trend at each of the sites. A comparison of the site natural attenuation evaluation is made to compare with the requirements for site closure under the Wisconsin Department of Natural Resources regulations and guidance. © 2003 Wiley Periodicals, Inc.     

Implementation of the semi-aerobic landfill system (Fukuoka method) in developing countries: a Malaysia cost analysis

Most of the existing solid waste landfill sites in developing countries are practicing either open dumping or controlled dumping. Proper sanitary landfill concepts are not fully implemented due to technological and financial constraints. Implementation of a fully engineered sanitary landfill is necessary and a more economically feasible landfill design is crucial, particularly for developing countries. This study was carried out by focusing on the economics from the development of a new landfill site within a natural clay area with no cost of synthetic liner up to 10 years after its closure by using the Fukuoka method semi-aerobic landfill system. The findings of the study show that for the development of a 15-ha landfill site in Malaysia with an estimated volume of 2,000,000 m(3), the capital investment required was about US 1,312,895 dollars, or about US 0.84 dollars/tonne of waste. Assuming that the lifespan of the landfill is 20 years, the total cost of operation was about US 11,132,536 dollars or US 7.15 dollars/tonne of waste. The closure cost of the landfill was estimated to be US 1,385,526 dollars or US 0.89 dollars/tonne of waste. Therefore, the total cost required to dispose of a tonne of waste at the semi-aerobic landfill was estimated to be US 8.89 dollars. By considering an average tipping fee of about US 7.89 dollars/tonne of waste in Malaysia in the first year, and an annual increase of 3% to about US 13.84 dollars in year-20, the overall system recorded a positive revenue of US 1,734,749 dollars. This is important information for the effort of privatisation of landfill sites in Malaysia, as well as in other developing countries, in order to secure efficient and effective landfill development and management.     

Tree establishment and growth at Pitsea landfill site,Essex, U.K.

Investigations at an 11-year-old landfill site have shown that soil moisture was positively, and soil oxygen was negatively correlated with temperature and concentration of soil methane generated by decomposition of the underlying landfill materials. A thin (0.2 m) cover of soil-forming material over the landfill showed acute oxygen deficiency and high temperatures. The high moisture content of this cover was probably caused by upward movement of water from within the landfill across a temperature gradient. Nearly all the trees of five species on the thinnest (0.2 m) cover died, but survival and growth was markedly improved on 1.5 m additional clay cover over the landfill. This material prevented landfill gas contamination, and also contained sufficient plant-available soil moisture to negate the large soil moisture deficits the area experiences in most summers. The evidence presented shows that landfill sites are dynamic in the distribution of landfill temperature and gas emissions and the planning of tree planting schemes should take this into account.     

Management status of end-of-life vehicles and characteristics of automobile shredder residues in Korea

An end-of-life vehicle (ELV) is dismantled to recover and recycle any re-usable parts, then shipped to the shredding facility for further recovery of iron with any remaining Automobile Shredder Residue (ASR) to be considered as wastes and to be disposed of by either thermal treatment or landfill. Overall ELVs management status in Korea, including recycling resulting from the dismantling processes, was surveyed using some questionnaires given to dismantlers and other available information to provide some feasible means for future treatment. The averaged recycle rate in the dismantling stage showed a value of 44% and the rest of an ELV was then compressed and transported to shredding companies to recover mainly the iron content which averaged 38.7% of the mass of a new vehicle. The non-ferrous metals such as copper, antimony, zinc and aluminum accounted for only 1.5%. The Shredder dusts (SDs) were found to be composed of light and heavy fluffs and soil/dust and amounted to 15.8% based on the mass of a new vehicle. Dumping of fluff and inorganic residues into a landfill site, however, will be restricted when new regulations are implemented to reduce the disposal amount to less than 5% of a new car as done in European countries and Japan. The detailed characteristics of SDs were investigated to provide an idea of how to treat them in order to meet a future expected enforcement.     

Case study: On-site remediation of soil and groundwater for a michigan town's water supply

In 1993 environmental consultants, working in concert with the State of Michigan, discovered groundwater contamination that threatened the drinking water supply of the town of Big Rapids. The contamination originated from leaking underground storage tanks and gasoline lines, which were removed. A pilot study indicated the contaminated area extended to 240′ x 180′ and affected soil as well as groundwater. A remediation plan was designed by and implemented by Continental Remediation Systems, Inc., a Natick, Massachusetts, firm. The remediation plan is ongoing and includes an interceptor trench to stop gasoline from flowing into the creek, as well as air sparging to vent and treat the contaminated soil. It is anticipated that the remediation project will take six months to complete. The chief advantage of on-site remediation is that it avoids the costs and liabilities associated with landfill disposal and no materials need leave the site.     

Remediation of groundwater contamination through conjunctive use of landfill gas management and soil vapor extraction

The recently completed performance testing of a conjunctive-use operation has demonstrated the applicability of combined landfill gas and Volatile Organic Compound (VOC) removal with overall contaminant migration management. The extraction of landfill gas (with subsequent control of off-site gas migration) and the removal of VOCs from the landfill gas/soil air environment will minimize VOC solubilization in the underlying groundwater. This, in turn, will permit cost efficient management of contaminant migration at the site.     

Incorporating green and sustainable remediation analysis in coal combustion residuals (CCR) surface impoundment closure decision making

In response to new coal combustion residuals (CCR) disposal regulations, many coal‐fired utilities have closed existing unlined surface impoundments (SIs) that were traditionally used for disposal of CCR. The two primary closure options are closure‐in‐place (CIP), which involves dewatering and capping, and closure‐by‐removal (CBR), which includes excavation, transportation, and disposal of the CCR into a lined landfill. This article provides a methodology and a case study of how green and sustainable remediation concepts, including accounting for the life cycle environmental footprints and the physical risks to workers and community members, can be incorporated into the closure decision‐making process. The environmental impacts, occupational risks, and traffic‐related fatalities and injuries to workers and community members were calculated and compared for closure alternatives at a hypothetical site. The results demonstrated that the adverse impacts of the CBR option were significantly greater than those of the CIP option with respect to the analyzed impact pathways.     

Mitigation of methane emission from Fakse landfill using a biowindow system

Landfills are significant sources of atmospheric methane (CH₄) that contributes to climate change, and therefore there is a need to reduce CH₄ emissions from landfills. A promising cost efficient technology is to integrate compost into landfill covers (so-called “biocovers”) to enhance biological oxidation of CH₄. A full scale biocover system to reduce CH₄ emissions was installed at Fakse landfill, Denmark using composted yard waste as active material supporting CH₄ oxidation. Ten biowindows with a total area of 5000 m² were integrated into the existing cover at the 12 ha site. To increase CH₄ load to the biowindows, leachate wells were capped, and clay was added to slopes at the site. Point measurements using flux chambers suggested in most cases that almost all CH₄ was oxidized, but more detailed studies on emissions from the site after installation of the biocover as well as measurements of total CH₄ emissions showed that a significant portion of the emission quantified in the baseline study continued unabated from the site. Total emission measurements suggested a reduction in CH₄ emission of approximately 28% at the end of the one year monitoring period. This was supported by analysis of stable carbon isotopes which showed an increase in oxidation efficiency from 16% to 41%. The project documented that integrating approaches such a whole landfill emission measurements using tracer techniques or stable carbon isotope measurements of ambient air samples are needed to document CH₄ mitigation efficiencies of biocover systems. The study also revealed that there still exist several challenges to better optimize the functionality. The most important challenges are to control gas flow and evenly distribute the gas into the biocovers.     

Environmental project management using fast-track methods to save time and money

In 1992, Eaton Corporation, a major manufacturer of vehicle components and electrical and electronic controls, implemented a fast-track remediation method to expedite the installation of a groundwater recovery and treatment system to contain and mitigate a chlorinated solvent plume at an industrial site. This dual-track method included fast-track and turnkey project management techniques. Our goal was to expedite the containment and removal of identified contamination, which would protect the environment, minimize future liability, and significantly reduce remediation time and costs. This goal was in the best interests of all concerned—Eaton, the community, and the state regulatory agency. This strategy took the project from dual-track concept approval by the regulatory agency to remediation system installation and start-up in less than eight months, cutting over two years from the standard Remediation Investigation/Feasibility Study (RI/FS) approach, with consequent earlier contaminant containment. Total remediation costs were half of what they would have been under the standard RI/FS procedure for this site.     

Landfill aeration in the framework of a reclamation project in Northern Italy

In situ aeration by means of the Airflow technology was proposed for landfill conditioning before landfill mining in the framework of a reclamation project in Northern Italy. A 1-year aeration project was carried out on part of the landfill with the objective of evaluating the effectiveness of the Airflow technology for landfill aerobization, the evolution of waste biological stability during aeration and the effects on leachate and biogas quality and emissions.The main outcomes of the 1-year aeration project are presented in the paper.The beneficial effect of the aeration on waste biological stability was clear (63% reduction of the respiration index); however, the effectiveness of aeration on the lower part of the landfill is questionable, due to the limited potential for air migration into the leachate saturated layers.During the 1-year in situ aeration project approx. 275 MgC were discharged from the landfill body with the extracted gas, corresponding to 4.6 gC/kgDM. However, due to the presence of anaerobic niches in the aerated landfill, approx. 46% of this amount was extracted as CH₄, which is higher than reported in other aeration projects. The O₂ conversion quota was lower than reported in other similar projects, mainly due to the higher air flow rates applied.The results obtained enabled valuable recommendations to be made for the subsequent application of the Airflow technology to the whole landfill.     

Rehabilitation of El Yahoudia dumping site, Tunisia

As in all developing countries, cities in Tunisia face serious problems of environmental pollution caused mainly by the inadequate and inefficient final disposal of their generated solid wastes. The Tunisian government launched a development program including the construction of landfills in the main cities and the closure of the contaminated sites issued from solid wastes landrising practice. The project of the Henchir El Yahoudia landfill restoration is the first experience in this programme. It has been suggested to convert the site to a green park and to implement an ornamental plant nursery. The whole surface of the landfill is approximately 100 ha from which 30 ha have been already transformed to an urban recreational area and the remaining 70 ha have to be characterized for the project extension. A field investigation by boring was conducted in order to define the geological and the hydrogeological conditions, the vertical and horizontal wastes layer extension, content and degree of decomposition and the composition and quantities of leachate and landfill gas. Representative samples of waste, soil, groundwater and leachate were collected for laboratory analyses. Several of these borings were converted to piezometers to define the flow regime in the site. The results showed that the biogas (CH4, H2S, and CO2), leachate and waste, distribution in the site is mainly affected by the temporal variation of the site operating method. The underlying fissured clay layer facilitated leachate infiltration into the groundwater where high BOD, COD and nitrogen concentrations were registered.