Landfill leachate pilot awarded - Environmental Expert (press release)

Dynatec was awarded a contract in late 2011 to provide a turnkey pilot system for landfill leachate treatment for the City of Calgary. Here is their news release.

(Above video is by another MBR company but we thought it would be of interest. Dynatec do not appear to have produced a video of their product for YouTube.)

Dynatec was the only company to respond to the tender that has experience in producing pilot systems of this type and proven experience with landfill leachate treatment systems.  CH2M Hill is the city's engineer. The contract value is around $1M.  The system is expected to start up later this year.

Landfill leachate is a difficult wastewater to treat.

The leachate to be treated in this project includes high BOD and COD, heavy metals, and high ammonia. We face the challenge to evaluate treatment processes to either discharge to a POTW or directly to surface or ground water. The system will have to operate under extreme conditions with temperatures reaching -400. The system is designed for flexibility to evaluate different treatment processes.

Dynatec will use chemical pretreatment followed by our Hi-Rate MBR with aerobic and anoxic (MLE process) and a two-pass RO system. The pilot system will be containerized for mobility because the city wants to be able to test the process at other facilities.

Why Dynatec?  Dynatec has extensive experience in difficult wastewater treatment applications such as this one. Projects like the hazardous landfill in Bellevue, MI have given us the experience required to succesfully execute this type of project.

View the original article here

Dynatec Provides MBR System for Hazardous Landfill

The Problem

A hazardous waste landfill in Belleville, MI, owned by the Environmental Quality Company had a problem. They needed to develop a treatment process to remove COD, high TDS, heavy metals, phenol, PCB’s, Ammonia, and Molybdenum from the landfill leachate. Current treatment comprised of chlorination and activated carbon treatment was very costly.

Evaluation

The treatment process was challenging. The chemical treatment supplied was based upon the experience batch treating the wastewater and numerous bench scale treatability studies. An MBR process was selected for piloting because it was the best option to nitrify, reduce the high COD and phenol and overcome the potentially toxic conditions. Dynatec was engaged to supply a pilot treatment plant to be used as an investigative tool for the design of the full scale treatment process. The pilot operation phase of the project lasted almost 3 years, where problems were identified and solutions found.

Some unique challenges offered by this application were:

Foaming - Toxicity from the metals, phenol , and other unidentified substances

Mixed Liquor conditioning

Biological temperature sensitivity

Sensitive nitrification process

Difficult chemical precipitation of metals

Small footprint required

Dynatec was engaged to supply and install the full scale system because of Dynatec’s experience with the treatment technologies employed, their familiarity with the project, and the requirement for a high rate MBR process operating at high MLSS.

The Solution

Dynatec provided and installed a system that included a stainless steel insulated covered bioreactor with both heating and cooling capabilities to control temperature within a range suitable for achieving the treatment goals. To solve the foaming problem, a combination of jet aeration, defoamer, DO control, and concentrate return splash plates were employed along with an emergency potable water spray to prevent foam-over.

The membrane filtration equipment was designed to make efficient use of a small existing building that houses the membranes, controls, dewatering and other equipment.

The process includes chemical / physical treatment of the leachate both before and after the MBR. The post MBR chemical precipitation is for Molybdenum. The MBR removes compounds that were found to interfere with the precipitation process. The treated water is discharged to sanitary sewer.

A sludge tank receives the solids from both clarifiers of the pre and post chemical treatment systems as well as the WAS. Additional iron and lime is added and mixed in the sludge tank prior to feed to the filter press for dewatering. The solids are discharged within the landfill.

The Process

The process design consists of the following:

The hazardous wastewater is pretreated for removal of CN, Cr, Cu, Pb, Ni and Zn.The hazardous wastewater is mixed with non hazardous wastewater in a 500,000 gallon EQ tank to help make nitrification work. Approximately 65% of the wastewater discharged to the EQ tank is hazardous WW and 35% is non haz.The WW in the EQ tank is sent to the MBR for treatment for reduction in phenol ammonia nitrogen and COD.The MBR permeate is post treated for removal of molybdenum. The moly is apparently organically bound and does not precipitate adequately in the pretreatment.Sludge from the metals precipitation is mixed with WAS and dewatered in a filter press.

Operation

The system started up in March of 2010. As expected, the activated sludge took less than two months of conditioning before effective treatment was achieved due to the information and knowledge that was gained during piloting. A special bacterial culture was added to promote nitrification, which improved performance.

The COD  of the hazardous wastewater varies significantly, typical values observed have been between 5,000 mg/L and 12,000 mg/L. After blending with non hazardous leachate the COD is typically in the range between 3,000 mg/l and 6,000 mg/l.

The system operator is able to adjust conditions as needed. The system is currently operating at high mixed liquor concentration, an average of 24,000 mg/l. The jet aeration system makes operation at this level possible. Temperature ranges from a low of 25’C in the winter to 36’C in the summer. A natural gas fired heater heats the leachate in the winter in the recirculating loop between the bioreactor and the UF. The heater runs very little as the tank is covered and insulated. The system also has the ability to cool the mixed liquor as the temperature approaches 38’C to prevent thermophilic conditions from developing.

The continuous addition of defoamer is necessary. The concentrate return hits splash plates in the reactor to create a spray of sorts to help depress foam. There is also a fresh water spray available for use that rings the top inside of the reactor.

After startup, the system is operating as designed. The operators have used the emergency potable water spray to prevent foam-over of the bioreactor a couple times, with no other major issues. The system is exceeding expectations. Phenol in the effluent is typically below 0. 1 mg/L and metals removal is consistently below discharge requirements and below toxicity levels required to protect the biological process.

Conclusion

This is a very tough job. The complete and comprehensive system that Dynatec provided made this a success, and many lessons were learned for future projects. Dynatec was the right choice for this difficult MBR application. The many years of experience Dynatec has applying membranes to wastewater has enabled it to design and provide systems that perform in even the most difficult applications.

The system payback is expected to be very short. The system is meeting all its treatment objectives.

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Ultrafiltration and Reverse Osmosis for Landfill Leachate Treatment - Environmental Expert

Lanchester Landfill serves Eastern Lancaster County and Western Chester County in PA for disposal of household and construction waste. The facility produces around 10,000 gals per day of  leachate.

The Problem

The facility ran a single basin sequential batch reactor (SBR) and a filter press to dewater the solids for many years, but found that they first, could not sustain a good biomass, and second, in winter could not nitrify the ammonia. The facility therefore could not reliably sustain the average monthly discharge requirements:

Evaluation

The purpose of the new system is was meet the discharge requirements consistently. Ultrafiltration and Reverse Osmosis technology was selected since this offers the best performance possible in the smallest footprint with a low capital cost.
The Solution

The existing SBR basin was converted to an equalization basin, and Dynatec provided and installed a prefilter to remove larger solids, an ultrafiltration system to remove fine colloidal solids and oils, a reverse osmosis system to remove TDS, and ammonia and the other dissolved components of concern.

Several tanks already in place were utilized as process and buffer tanks between the various treatment stages.

Final ph control and chlorination was also provided.

The Process

The leachate is equalized in an equalization basin. A filter removes large solids before it enters the UF process.The leachate is processed with ultrafiltration to remove particles and oils.The UF permeate is processed with Reverse Osmosis to remove dissolved materials.

Operation

The system has operated successfully for over five years, allowing the plant to meet its discharge permit on all parameters. The influent and effluent data are provided below.

Conclusion

Dynatec Systems has built on its water treatment experience that began in the 1970's using membranes with rugged industrial reliability to produce UF and RO systems wrapped in a compact package. This made Dynatec the right choice for this project. The successful implementation of this system allows this landfill to continue to discharge to the local POTW and for use for dust control on the facility’s roads.

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Impact of landfill caps on leachate emissions: an Austrian case study - Recycling News (press release)

Brussels -- Municipal solid waste (MSW) landfills, which consist of everyday consumer items, are potential long-term sources of emissions that could threaten the environment and human health if they are not managed carefully after closure. New research has presented a methodology to estimate future emission levels for closed MSW landfills and the impact of different aftercare strategies.

Kommunalunternehmen des Landkreises Bad KissingenGlobally, landfilling is the main method for disposing of solid waste. Highly industrialised countries, such as the US, the UK and Finland, extensively depend on landfilling their waste without any pre-treatment. As MSW landfills are possibly long-term sources of emissions, these sites need to be managed beyond closure. According to the EU Landfill Directive, which took effect in 1999, landfill operators have to continue managing sites after closure as long as the authority considers the landfill not likely to present a hazard to the environment any more.
Cap removed after 20 years

The researchers used an Austrian MSW landfill in Breitenau as a case study to evaluate emission levels from the site and to demonstrate the long-term environmental effects of installing a final cover to prevent emissions. This site was closed in 1989 and was capped with layers of gravel (0.2 metres) and sandy silt (0.9 metres). The temporary cap was removed after 20 years (in 2009) and a composite lining system was installed as the final cover. The study focused on one landfill compartment, which contained around 35,000 tons of MSW.

Leachate emissions decrease very slowly and may have environmental impacts for centuries to come. The approach to evaluate potential future emissions was based on a comprehensive assessment of the state of the landfill and included analysis of monitoring data, investigations of landfilled waste, and an evaluation of containment systems and site-specific factors, such as climate. Future emission levels were modelled and site-specific predictions of leachate emissions were presented.

Increased leachate after flushing

The results suggest that leachate concentrations increased considerably at the site when there was a change in the water flow pattern of the waste during final cover construction. Specifically, the concentrations of leachate pollutants chloride and ammonia-nitrogen increased from 200 to 800 milligrams per litre (mg/l) and 140 to about 500 mg/l, respectively. It is found that a period of intensive flushing after the change of the water flow pattern and before the final cover installation would have reduced the amount of leachable substances within the landfill and substance concentrations in the leachate would decrease to 11 mg/l of chloride and 79 mg/l of ammonia-nitrogen within 50 years.

Different aftercare strategies

A decline in water infiltration due to the installation of an impermeable top cover may lead to high substance concentrations in the leachate for centuries (above 400 mg of chloride per litre and 200 mg ammonia-nitrogen per litre), but with low associated annual emission loads (below 12 kg of chloride and 9 kg of ammonia-nitrogen per year). However, a gradual decrease in the cover?s performance may be expected without cover maintenance and would be associated with higher emission loads of a maximum of 50 kg of chloride and 30 kg of ammonia?nitrogen.

The methodology can be applied to other closed landfill sites to illustrate the effect of different aftercare strategies on the landfill pollution hazard. The researchers caution that emission models should be treated as tools to demonstrate the effect of different landfill conditions and not as deterministic forecasts of the future.

Original source: David Laner, D., Fellner, J. & Brunner, P.H. (2011) Future landfill emissions and the effect of final cover installation ? A case study. Waste Management. 31 (7):1522-1531

Quelle: EU commission

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Waste Degradation and the Idea of Acceptable Release Rate

Every landfill is an engineering project with an engineered leachate management system. Any landfill liner is part of the system. The system should be designed to accommodate a range of seepage rates from very low (the best containment that can be achieved) to high (a controlled form of dilute and attenuate) depending on the degree of environmental protection needed at that site.

Many guidance documents or statutory assessment methods use absolute terms such as "total containment", "prevention of leachate and landfill gas migration", or "impermeable". These terms can lead to the erroneous belief that such concepts are achievable, and that failure to do so is indicative of poor materials or workmanship.

Landfill Problems - A Landfill Site Anatomy - kewego
http://landfill-site.com/html/landfills__environmental_probl.php Landfill problems. Landfill lining requirements, capping and landfill restoration described. Protect the environment and groundwater.

Keywords: landfill landfills trash problems groundwater pollution waste management

Video from stevideo

Consideration of material properties demonstrates that, as all materials have a finite permeability, some finite seepage is inevitable.

For example, the frequently quoted requirements for one metre of clay with a maximum permeability of 10-9 m/s and a maximum leachate head of 1 metre implies, using Darcy's Law, a seepage rate of 1.7 m^/d/ha, and yet it is commonly referred to as the provision of "total containment".

Actual flow rates are affected by a range of ameliorating and aggregating factors. Calculation of actual seepage rates is complex, and should be carried out using risk assessment methodology carried out to a recognized methodology.

For gases, viscosity and diffusion characteristics must be taken into account. In general, mineral liners on their own are not usually effective barriers against gas migration, though they can be useful components of a multi-barrier system.

Measurements of hydraulic conductivity are of little relevance in respect to gas, as gas is able to pass through a barrier at a rate several orders of magnitude greater than that which may be measured for water.

All materials will allow the passage of liquids to an extent determined by their permeability. Risk assessment methodology will quantify the probability distribution for a derived seepage rate for a given liner/landfill situation.

This should be used either to assess the probable impact on the receiving source, or to determine the performance specification for the liner and landfill operational methods. In this way, an appropriate liner specification can be derived, incorporating a suitable safety margin.

Excessive over-engineering should be avoided, as this can itself may be considered to contravene the principles of sustainable development.

The statement we have made regarding the fact that flow through landfill containment systems will never be absolutely zero and will be a quantifiable small amount, cannot be refuted. It is a rigorously scientific approach to adopt this principle.

However, the concept of the fact that a seepage through a liner is acceptable has been resisted by some, and in particular can appear to be in conflict with the EC Groundwater Directive.

However, in certain circumstances, the discharge into the unsaturated zone of leachates containing List II substances (as defined by the EC Groundwater Directive) is permissible, provided that prior investigation has shown that this will be satisfactory and not significantly impact upon the environment.

Around the globe the primary concern will be to ensure the protection of groundwater, so for example in the EU landfill acceptability is classified by type within zones of travel time to a water source, and within resource protection areas.

Landfills are accepted as suitable for development when subject to adequate risk assessed engineered containment and operational safeguards.

Author Steve Evans has been writing about landfill daily cover and many other aspects of practical waste and secondary resource management since 2006. As you have been reading this article, there is a fair chance that you may enjoy his blog. We recommend a visit now!