Liquid Injection to Enhance Biogas Production in Landfills for Pretreated Municipal Solid Wastes - BIO.LEA.R. Project (Life+ Program)

Abstract

The Bio.Lea.R project aims to demonstrate the performance of a landfill for less reactive, biologically treated waste (pretreated organic wastes) compared to a conventionally managed landfill, with regard to both environmental (biogas and leachate production) and economic aspects. The objective is to control the pretreated biodegradable waste through a liquid injection in order to achieve the same biogas quantity in a shorter time than in conventional landfill. Laboratory and full scale monitoring were performed in order to check the efficiency of the landfill acting as bioreactor. A smallscale lysimeter was set up to simulate in laboratory the biological processes that happen at a bioreactor landfill. The lysimeter consists of a cylindrical reactor filled with waste. The monitoring activity of the geophysical parameters of the landfill is based on network of geophysical sensors to detect the changes in time and space of the electrical conductivity at different depth in the landfill. Electrical conductivity is potentially a good indicator of spatial and temporal changes of liquid content of the waste within, as results of the infiltration process. Results of the lysimeter experiment have proved the faster production of biogas, with the Methane Potential Yield at 900 days. The current modeling of leachate infiltration is influenced by availability of experimental data which in this case are provided by time lapse monitoring of geophysical parameters. The combination of time-lapse geophysical monitoring, advanced inversion technique and traditional waste sampling techniques provides robust data to evaluate the infiltration process and degradation of waste.

Behavior of Rejects from a Biological-Mechanical Treatment Plant on the Landfill to Laboratory Scale

“…However, in the lysimeters without recirculation, the COD value is 29.1% lower when chemical and biological activity ceases. The values at the end of the experiment were similar to those of a leachate of an intermediate age with levels of 10,000-12,000 mg/L [48] or 18,380 mg/L [21], but with higher levels than those of old leachates with 4880 mg/L [44], 5350 mg/L [51], or 5280 mg/L [21], and with lower values than for fresh leachate, with 69,600 mg/L [44] or 70,900 [51]. It was assumed that waste degraded (biodegradable fraction) until the maximum values were reached in week 3.…”

“…Moisture was lower than in the rejects from an MBT plant as this sort of BMT plant applies biodrying before mechanical separation. The moisture of the rejects from the mechanical process of typical MBT plants in Spain ranges from 30% to 35% [5,6], and is about 25%-30% in Italy [21], and 30.2% in Thailand [28]. However, it was 17%-21% for rejects in the present work.…”

“…These data are similar to the results obtained from fresh leachate in landfills, like those offered by Tatsi and Zouboulis (2002) [44], with values of 23. [21]. They are higher than those from leachate of intermediate age (5-10 years), with values of 4.1-1.4 mS/cm [48] or 8.1-4.2 mS/cm [15].…”

“…However, it was 17%-21% for rejects in the present work. Conversely, the moisture in other works conducted with lysimeters (with MSW as a substrate) was 52% [20], 41.1% [32], 41% [21], 40.4% [23], 32% [24] and 29.3% [25]. Therefore, in landfills with rejects from BMT plants, the waste mass reaches the FC later because of the lower moisture, and it would take longer to generate leachates.…”

“…Aljaradin and Persson (2016) [20] conducted a comprehensive study to monitor the emission potential from solid waste landfilled in Jordan using an anaerobic lysimeter. Godio et al (2015) [21] developed a small-scale lysimeter which was set up to simulate the biological processes that take place in a bioreactor landfill with rejects from an MBT plant under laboratory conditions.…”