Variations in Microbial Flora in Different Phases of Refuse in Response to Dibutyl Phthalate

Simulated municipal solid waste (MSW) based on the actual proportional characteristics of MSW was loaded into a simulated leachate recirculation bioreactor landfill and the abundance of common and tolerant microbes exposed to dibutyl phthalate (DBP) were investigated in the initial, acidic and methanogenic phases. The results showed that the abundance of bacteria was greatest, while that of actinomycetes was smallest. The growth of microorganisms was not significantly inhibited by DBP during the initial phase; however, the growth of actinomycetes and fungi was inhibited during both the acidic and methanogenic phases, and the inhibition of actinomycetes was greater than that of fungi. When the DBP concentration was 5.0 g l-1, the inhibition ratio against actinomycetes was 89.5% and 80.9% in the refuse from the acidic phase and methanogenic phase, respectively, while it was 86.2% and 51.0%, respectively, against fungi during the same period. The toxic effects of DBP on microorganisms in refuse occurred in the order of actinomycetes > fungi > bacteria. In addition, the populations of bacteria, fungi and actinomycetes were significantly and positively correlated with dehydrogenase activity, but negatively correlated with the VSS and BDM of refuse (P<0.01).

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Management of the biodegradable fraction of residual waste by bioreactor landfill

Waste Management & Research ◽

10.1177/0734242x20953496 ◽

2020 ◽

Vol 38 (10) ◽

pp. 1153-1160

Author(s):

Francesco Di Maria ◽

Mervat El-Hoz

Keyword(s):

Municipal Solid Waste ◽

Solid Waste ◽

Biological Treatment ◽

Electrical Energy ◽

Integrated System ◽

Bioreactor Landfill ◽

Organic Fraction ◽

Leachate Recirculation ◽

Solids Concentration ◽

Volatile Solids

The performances of an integrated system based on mechanical biological treatment and bioreactor landfill with leachate recirculation for managing the mixed municipal solid waste generated in a given Italian district were investigated. In the mechanical biological treatment the municipal solid waste was mechanically sorted into two main streams: a dry and a mechanically sorted organic fraction consisting of 45,000 tonnes year−1. After being sorted the mechanically sorted organic fraction was aerobically pretreated before being disposed of in the 450,000 m3 bioreactor landfill. Experimental runs showed that an aerobic pretreatment period ranging from 15 to 30 days was able to maximize the methane generated by the mechanically sorted organic fraction once landfilled up to 10 Nm3 tonne−1. The aerobic pretreatment leads to a significant volatile solids reduction in the first 30 days, after which the volatile solids concentration remained quite constant. Similarly the potential dynamic respirometer index was significantly reduced in the first 15 days of the aerobic pretreatment decreasing from about 5,000 to about 3,500 mgO2kgVS−1h−1. The whole amount of electrical energy producible by the landfill ranged from 18.5 kWh tonne−1 to 21 kWh tonne−1, depending on the strategies adopted for the activation in bioreactor mode of each landfill cell by the leachate recirculation.

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DecoMSW: A Methodology to Assess Decomposition of Municipal Solid Waste for Initiation of Landfill Mining Activities

The Journal of Solid Waste Technology and Management ◽

10.5276/jswtm/2021.465 ◽

2021 ◽

Vol 47 (3) ◽

pp. 465-481

Author(s):

Arif Mohammad ◽

Venkata Siva Naga Sai Goli ◽

Agnes Anto Chembukavu ◽

Devendra Narain Singh

Keyword(s):

Municipal Solid Waste ◽

Solid Waste ◽

Nitrate Nitrogen ◽

Spatial And Temporal Variation ◽

Mining Activities ◽

Bioreactor Landfill ◽

Chemical Parameters ◽

Landfill Mining ◽

Humus Substances ◽

Volatile Solids

Biochemical decomposition of municipal solid waste (MSW) in landfills leads to the generation of leachate, gases and humus substances. In this context, a methodology to assess D ecomposition of MSW, designated as DecoMSW, has been developed; based on a series of tests conducted on samples of the fresh MSW and those retrieved from the active bioreactor landfill (BLF) cells of age from 13 to 48 months. Furthermore, spatial and temporal variation in the (i) physical (composition) and (ii) chemical (pH, volatile solids, total organic carbon, elemental analysis, ammonium and nitrate-nitrogen, biomethanation potential, lignocellulosic content) characteristics of the MSW samples exhumed from the landfill have been established. Finally, these characteristics were correlated vis-à-vis the respective values of the fresh MSW. From this exercise, it has been observed that except for nitrate-nitrogen, all other chemical parameters of MSW decrease exponentially with time until 20 months, and beyond that, they remain constant, which is an indication of stabilization of MSW. In short, it has been demonstrated that DecoMSW is instrumental in assessing the state of decomposition of MSW with respect to time in the BLF and facilitates initiation of the landfill mining activities.

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