Aerobic bioreactor landfill

4 CONCEPTS OF LANDFILL AERATION 4.4.1 Aerobic bioreactor landfill 

Pump and Treat Aerobic Flushing Bioreactor Landfill (PTAFBL), in which recalcitrant organics are oxidized both in-situ and ex-situ to the landfill (Fig. 4.2) is the new modified version of an aerobic landfill. This type of aerobic bioreactor was tested in pilot-scale by Bolyard et al. (2013). The Fenton s reagent was used for ex-situ leachate treatment because of its high efficiency in the removal of COD from leachate (Batarseh et al. 2007). The leachate containing oxidized organic compounds is returned to the landfill, where it was treated 

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In the United States, the concept of aerobic bioreactor landfill where the wastes are subjected to the active aeration from the early phase of landfill lifetime, was developed. Additionally, in order to accelerate the waste stabilization, the leachate recirculation is used. In Asia, the other solution for the reduction of methane production inside the landfill was elaborated. It consists in landfill self-aeration caused by the differences in inner and outer landfill temperatures (Fukuoka method). 

Aerobic bioreactor landfill technology enhances the rate and the extent of settlement. It was confirmed by both the laboratory and field studies. Erses et al. (2008) noticed that the settlement achieved in the simulated aerobic bioreactor was about 37% after 374 days, while in the anaerobic bioreactor it was only about 5% after 630 days. Giannis et al. (2008) reported 26% waste settlement in laboratory aerobic bioreactor (with leachate recirculation) after 510 days. 

Law, I, Peterson, E. Hudgins, M. Water requirement estimates for an aerobic bioreactor landfill in China. Proceedings Sardinia 2011, Thirteenth International Waste Management and Landfill Symposium S. Mar erita di Pula, Caghaii, Italy 3 7 Octobei 2011. CISA, Environmental Sanitary Engineering Centre, Italy. 

Some of these preventive and protective measures are described in Mitigation of Landfiii Gas Emissions. Special attention is given to the application of anaerobic, aerobic and semi-aerobic bioreactor landfills for control of landfill gas emission. Different types of biotic systems for the oxidation of methane and trace gases, such as biocovers, biofilters, and biowindows, are also presented. 

Hybrid (aerobic-anaerobic). The hybrid bioreactor landfill accelerates waste degradation by employing a sequential aerobic-anaerobic treatment to rapidly degrade organics in the upper sections of the landfill and collect gas from lower sections. Operation as a hybrid results in an earlier onset of methanogenesis compared to aerobic landfills. 

ASTM D7475-11, Standard Test Method for Determining the Aerobic Degradation and Anaerobic Biodegradation of Plastic Materials under Accelerated Bioreactor Landfill Conditions, American Society for Testing and Materials, PA, USA, 2011. 

Figure 3.2 Concept of hybrid (aerobic-anaerobic) bioreactor landfill (according to US EPA).

The aerobic-anaerobic bioreactor landfill technology is not widespread in the world. It was applied in the field scale in North America at the Metro Recycling/Disposal landfill in Wisconsin (Kidman et al. 2011). 

Figure 4.2 Concept of pump and treat aerobic flushing bioreactor landfill (Bolyard et al. 2013).

Bolyard, S.C., Reinhart, D.R. Santra, S. 2013. Pump and Treat Aerobic Flushing Bioreactor Landfill. Sinks a Vital Element of Modem Waste Management 2nd Intemational Conference on Final Sinks 16-18 May 2013 Espoo, Finland. 

Giannis, A., Makripodis, G., Simantiraki, F, Somara, M. Gidarakos, E., 2008, Monitoring operational and leachate characteristics of an aerobic simulated landfill bioreactor. Waste Management, 28 (8), 1346-1354. 

He, F, Yang, N., Gu, H., Zhang, H. Shao, L.J. 2011. N O and NHj emissions from a bioreactor landfill operated under limited aerobic degradation conditions. Environ Sci China) 23(6) 1011-1019. 

In this book, several ways to reduce the negative impact of landfill on the environment are presented. Consecutive chapters presenting the concepts of anaerobic bioreactor, aerobic and semi-aerobic bioreactors, deal with possible influences on gas emissions by the modification of the conditions prevailing in the waste deposit. The last chapter raises the issue of efficiency of microbiological oxidation processes, which remove methane and trace gases from landfill gas in different types of biotic systems, such as biocovers, biofilters, or biowindows. 

The aerobic biofilter used in the study had a capacity of 10 L. The reactor was packed to 60% of the empty bed volume with Cosmo ball media. The biofilter was seeded with active innoculum taken from an active aerated lagoon of a nearby landfill leachate treatment. Fresh raw leachate was used as feed to the reactor at a rate of 5 L/d over 24h. The loading rates applied to the bioreactor were between 1.6 and 22.2 kg COD/m3d. Initial studies were conducted as a batch process lasting for a period of 24 d. Thereafter, the biofilter was fed continuously for a total period of 240 d. 

During 150-day laboratory experiment on sohd waste stabilization in simulated landfill bioreactors, pH of leachate in aerobic reactor rapidly increased from 5-6 to ca. 1 during 40 days, and then it was gradually growing to values of 8-9, until the end of the study. The pH values of leachate of the anaerobic reactor was less than 5.5 until the day 100, which reflected the accumulation of volatile acids generated in an acidogenesis phase. Next, the pH value slightly increased to ca. 6 at the end of the experiment (Sekman et al. 2011). 

Giannis et al. (2008) showed that the simulated aerobic landfill bioreactor could remove above 90%) of chemical oxygen demand (COD) and almost to 100%o of biochemical oxygen demand (BOD ) from leachate. The conversion of anaerobic to aerobic landfill (with leachate recirculation) performed in field scale reduced biological oxygen demand (BOD) of leachate up to 70%) within 3 months of aeration (Read et al. 2001b). 

The studies carried out in simulated landfill bioreactors by Sekman et al. (2011) showed that alkalinity levels in the aerobic and anaerobic reactors were >3500 mg CaCOj dm from the beginning to the end of the experiment. Alkalinity in both types of reactors showed considerable fluctuations. 

Yazdani, R., Mostafid, E., Han, B., Imhoff, R, Chiu, R, Kayhanian, M. Tchobanoglous, G, 2010. Performance of enhanced aerobic landfill bioreactor under air How and liquid addition. Abstracts of Papers, 239th ACS National Meeting, San Francisco, CA, United States, March 21-25. 

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