Leachate recirculation

Control of ga.s movement by recovery. The movement of gases in landfills can also be controlled by instadhng gas-recovery wells in completed landfills (see Fig. 25-74b). This is considered an active venting system. Clay and other hners are used when landfill gas is to be recovered. In some gas-recovery systems, leachate is collected and recycled to the top of the landfill and reinjected through perforated lines located in drainage trenches. Typically, the rate of gas production is greater in leachate-recirculation systems. 

Modrak, M., Hashmonay, R.A., Varma, R., and Kagann, R., Measurement of Fugitive Emissions at a Landfill Practicing Leachate Recirculation and Air Injection, U.S. Department of Commerce, National Technical Information Service, Springfield, VA, 2005, 58 p. 

Changes to landfill operation, such as operating under wet conditions through leachate recirculation or other liquid additions, will result in generating more gas at a faster rate but with this software such operations were not considered [7],... 

For effective co-disposal, the draft document for consultation (DoE, 1994a) states that "flushing bioreactor conditions are needed. This leads to a separate requirement for containment and possibly recirculation" (see Chapter 7). Under enlumced conditions of gas generation (and hence microbial activity) the potential for effective co-disposal will be enhanced accordingly. Although at the moment very few landfill sites undertake leachate recirculation, it is a concept that is receiving a great deal of attention and one that appears to facilitate both codisposal practice and more sustainable landfill development. 

Figure 12 High rate leachate recirculation concept (Knox and Gronow, 1993) Reproduced with permission...

Doedens, H. and Cord-Landwehr, K (1989) Leachate recirculation. In Sanitary Landfilling Process, Technology and Environmental Inqtact (Christensen, T.H., Cossu, R. and Stegmann, R. eds.) Academic Press, London. 

Pohland, F.G. (1989) Leachate recirculation for accelerated landfill stabilisation. In Sardinia 89 Proceedings of the second international landfill symposium. Porto Conte. XXX, ppl-8, CIPA, Milan... 

If it is desired to speed up decomposition in a landfill environment, leachate recirculation can be used. In such systems, instead of pumping out, treating, and discarding any liquid effluent which reaches the top of the landfill liner, the liquid which is pumped out is reintroduced... 

Biodegradation. Current studies have shown that wet systems, or landfills that use leachate recirculation, are becoming the favored option when considering solid waste stabilization as a priority for the landfill. Since most biodegradation results from... 

Depending on the similarity theory, two laboratory simulation experiment devices were developed. Both devices I and II consist of a cover layer, a waste layer, a drainage layer, a compacted clay layer, a leachate recirculation system, as well as a few test instruments (Fig. 1). The seepage characteristics of leachate in compacted clay layers were determined through simulation experiments. 

Knox, K. 1995. Leachate Recirculation and its Role in Sustainable Development. 5th Joint INCPEN/ IWM/BPF Seminar. 

High organics content in waste High moisture content - leachate recirculation... 

Source separated municipal biowaste Laboratory scale, semi-continuous reactor, V = 4,5 dm wet fermentation, thermophilic conditions (55°Q, leachate recirculation HRT 14-18 0.63-0.71 m B kg VS- Hartmann Ahrig, (2005)... 

Designing a system for leachate recirculation and distribution of liquids inside the bioreactor landfill. 

Decrease of pollutant concentrations in the leachate. Positive effects in the reduction of leachate strength in a full-scale bioreactor landfill were observed at Sea Carr Landfill. The COD in the leachate from the area with recirculation was always lower than in the control area (without recirculation). The differences became more apparent with time. After three years of observation the COD values in the recirculated leachate were approximately 15 g dm while in the control they exceeded 50 g dm . A similar trend was observed in the case of chlorine, and ammoniacal-N. During three years of observations concentrations of these substances decreased in both cells, but the lower values and a more pronounced drop were noticed in the cell where leachate recirculation was applied. After three years, the chlorine and ammoniacal-N concentrations in the recirculated leachate was about 1,600 and 500 mg dm" respectively, while in the leachate from the control cell they were about 2,100 and 800 mg dm, respectively (Bioreactor Landfill for Sustainable..., 2004). Recirculation of leachate from an active or closed landfill cell can be considered as an in situ leachate treatment method. It minimizes the hazard to the environment and reduces the leachate treatment costs (Reinhart et al. 2002). Due to the continuous recirculation of leachate the operator does not bear the costs associated with its pre-treatment and transport to the treatment plant. 

Increased sanitary risk due to surface leachate recirculation. 

Erses, SA. Onay, T.T., 2003. Accelerated landfill waste decomposition by external leachate recirculation from an old landfill cell. Water Sci Technol. 47(12) 215-22. 

Francois, V., Feuillade, G., Matqka, G., Lagier, T. Skhiri, N. 2007. Leachate recirculation effects on waste degradation Study on columns. Waste Management 27 1259-1272. 

Soh, I. Hettiaratchi, J. 2009. Potential lateral migration of leachate in fludting bioreactor landfills during aggressive leachate recirculation. Pract. Period. Hazard. Toxic Radioact. Waste Manage. 13. SPECIAL ISSUE Advances in Solid Waste Management Technology 174-178. 

Sponza, D.T. Agdag, O N. 2004. Impact of leachate recirculation and recirculation volume on sta-bihzation of municipal solid wastes in simulated anaerobic bioreactors. Process Biochemistry 39 2157-2165. 

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