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.

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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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Comparison of four leachate-generation procedures for solid waste characterization in environmental assessment programs (Interagency energy/environment R&D program report)

FROM THE PREFACESanitary landfills are the most widely utilized method of solid waste disposal around the world. With increased use and public awareness of this method of disposal, there is much concern with respect to the pollution potential of the landfill leachate. Depending on the composition and extent of decomposition of the refuse and hydrological factors, the leachate may become highly contaminated. As leachate migrates away from a landfill, it may cause serious pollution to the groundwater aquifer as well as adjacent surface waters. There is growing concern about surface and groundwater pollution from leachate. Better understanding and prediction of leachate generation, containment, and treatment are needed.

This book contains a literature review of various methodologies that have been developed for prediction, generation, characterization, containment, control, and treatment of leachate from sanitary landfills. The contents of this book are divided into nine chapters. Each chapter contains theory and definition of the important design parameters, literature review, example calculations, and references. Chapter 1 is devoted to basic facts of solid waste problems current status and future trends towards waste reduction and recycling. Chapter 2 provides a general overview of municipal solid waste generation, collection, transport, resource recovery and reuse, and disposal options.

The current status of sanitary landfill design and operation, problems associated with the landfilling, and future trends are presented in Chapter 3. Methods of enhanced stabilization, recycling landfill space, methane recovery, and above grade landfilling, and closure and post closure care of completed landfills are also discussed in detail. Chapter 4 provides a general overview of Subtitle D regulations and its impact upon sanitary landfilling practices. Chapter 5 is devoted entirely to moisture routing and leachate generation mechanisms.

Examples of calculation procedure for determining the leachate quantity produced at a landfill are presented. Chapter 6 is devoted to chemical characterization of leachate that changes over the life of the fill. Both theoretical and experimental results are provided to estimate the leachate quality. Chapter 7 provides leachate attenuation processes and mechanisms.

Chapter 8 is devoted to leachate collection systems. Natural soil sealants, admixed materials and synthetic membranes, their effectiveness, and methods of installation and economics are fully discussed. Chapter 9 provides a detailed review of leachate treatment methodology. Kinetic coefficients and treatment plant design considerations are summarized for the sole purpose of assisting con- sultants to design leachate treatment facilities. Leachate treatment case histories and numerous process trains are presented for treating leachate from young landfill. The book also describes how the process train can be changed effectively as leachate quality changes with time.

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