DAS Technologies for the Treatment of Landfill Leachate
Landfill leachate is mainly caused by the seepage of rainwater and surface water from waste utilisation sites, but also by the inherent moisture of the waste and — in the case of inadequately sealed landfills — by the penetration of groundwater and external water. If leachate reaches bodies of water untreated, it poses a risk to the environment.
DAS Environmental Experts offers technology solutions which, depending on the leachate composition and
site can be used both as a stand-alone solution and in a combination of processes and reliably clean the landfill leachate. For example, biological wastewater treatment processes such as MBBR, activated sludge processes, Annamox and loop reactors, as well as reverse osmosis are used. If poorly degradable biological compounds remain in the wastewater, ozonation and/or activated carbon filters are used to remove these contaminants.
Special Features and Challenges of Leachate
Landfill sites generally contain a very inhomogeneous mixture of materials, which can contain both a very high organic content and soluble mineral substances. Some of the organic substances are already broken down by natural decomposition processes in the landfill body. Landfill leachate is usually very cloudy, has a typical strong odour, is brownish in colour and has a higher temperature than the surrounding groundwater.
The composition of landfill leachate depends on the type of waste stored, the weather and the service life of the landfill body. The older the landfill, the higher the proportion of poorly biodegradable organic compounds. If the landfill has been standing for a long time, the leachate is contaminated with a large number of water-soluble nitrogen and sulphur compounds, sulphates and chlorides as well as a high proportion of poorly biodegradable organic compounds.
It is often sufficient to treat the high organic and nitrogen load contained in the leachate to such an extent that it can be discharged to the nearest municipal sewage treatment plant for further treatment. If this is not possible, the wastewater must be treated to an effluent quality that meets the requirements for direct dischargers. In this case, the remaining pollutant load after treatment is so low that the treated landfill leachate can be discharged into a body of water. The technology experts at DAS EE are a reliable partner here.
Leachate Treatment with DAS Technology
A range of proven technologies are available for the treatment of landfill leachate. Our team of experts can offer you the right solution for your wastewater. On request, we will first analyse the specific composition of your leachate in our laboratory and then recommend an effective and cost-effective solution — whether as a stand-alone system or a combination of processes.
Landfill Leachate Treatment with Biological Processes as the First Stage
Biological treatment has proven itself in many cases as the first stage of treatment and also for nitrogen removal. MBBR, activated sludge processes, Annamox and loop reactors are used. A downstream ultrafiltration stage is very often used to retain the sludge produced in the biological processes. If difficult-to-degrade biological compounds remain in the wastewater, activated carbon filters or ozonation are used to remove the biorefractory impurities.
Landfill Leachate Treatment with Chemical-Physical Processes
Wet oxidative processes, such as ozonation, are used when it is possible to either completely oxidise organic pollutants or to convert biorefractory pollutants into biodegradable ones. In cases where organic pollutants in the leachate cannot be degraded by either biological or wet oxidative processes, activated carbon adsorption is used. The contaminants are first adsorptively bound and then thermally destroyed when the loaded activated carbon is incinerated.
Less common in the field of landfill leachate treatment is the use of precipitation/flocculation and ion exchange. Both technologies are used to reduce inorganic ionogenic contaminants.
A Chemical Site and its Contaminated Groundwater
As part of the remediation of a chemical site, DAS is responsible for treating the resulting leachate. Years of chemical production have left their mark: chlorinated hydrocarbons and metals have penetrated the soil through rainwater and contaminated the groundwater.
In order to clean the wastewater effectively, the affected area was separated with a sheet pile wall and well galleries were installed as part of the underground treatment. The wells are operated to keep the excavation pit dry. After pumping, the soil is separated and then loaded into containers for disposal. The pumped groundwater is first cleaned of metals by means of precipitation-flocculation, then a lamella lamella separator is used for sedimentation before the wastewater is fed into a sand filtration system. Nitrification and COD degradation take place in the subsequent biological stage (MBBR).
After another sand filtration stage, an activated carbon adsorption stage follows before the nitrogen load is eliminated with the aid of sodium hypochlorite. The wastewater treated in this way is now of a quality that allows it to be discharged directly into a river.