Landfill biofiltration system and methods for removal of gas-phase pollutants and contaminants

Abstract

Biochemical decomposition of undesirable gaseous contaminants, including nitrogen oxides, VOC's, carbon monoxide and sulfur oxides, and malodorous contaminants, is achieved by passing a gas stream through a managed landfill providing microbiological activity capable of degrading the contaminants. Gases suitable for treatment include fuel combustor exhaust, landfill gases, putrescent gases and the like. The landfill functions as a biological reactor (bioreactor), where water is added if or as necessary to achieve concentrations between about 20% and about 65% by weight, and desired microbial contaminant abatement action. By a permeation of the polluted gas through the landfill, there is a consumption of polluting gases by microorganisms present in the landfill. The process enables increased combustion of fuels, such as landfill gases, whose energy values are currently wasted or are not available due to emissions problems. The excess oxygen normally present in exhaust can advantageously result in additional oxidative waste consumption by microorganisms, yielding additional “air space” that is an economic bonus in extending landfill life and/or lessening landfill use.

What is claimed is:  
     
         1 . A method for removing biodegradable gaseous pollutants from contaminated gases, the method comprising: 
 permeating said contaminated gases into a large mass of managed waste, comprising a managed landfill or bioreactor, or managed waste pile; and    maintaining within said landfill or dump conditions whereby microorganisms present in said landfill biodegrade said gaseous contaminants to a level that meets statutory emission requirements or desired emission reductions.    
     
     
         2 . The method according to  claim 1 , wherein said gaseous pollutants comprise one or more of: nitrogen oxides; carbon monoxide (CO); sulfur oxides; and volatile organic compounds (VOC).  
     
     
         3 . The method according to  claim 2 , wherein said nitrogen oxides comprise one or more of nitrous oxide (N 2 O), nitric oxide (NO) and nitrogen dioxide (NO 2 ).  
     
     
         4 . The method according to  claim 2 , wherein said sulfur oxides comprise one or more of sulfur dioxide (SO 2 ) and sulfur trioxide (SO 3 ).  
     
     
         5 . The method according to  claim 1 , wherein said contaminated gases are exhaust gases from a combustion process.  
     
     
         6 . The method according to  claim 5 , wherein said exhaust gases are cooled to a temperature of less than about 150° C.  
     
     
         7 . The method of  claim 1 , wherein aqueous levels are maintained and available in said landfill bioreactor at a volume of from of 50 to 120 ml water per gram-atomic weight of oxygen consumed in the biodegradation reaction.  
     
     
         8 . The method of  claim 7 , wherein said aqueous amendment comprises buffers and nutrients.  
     
     
         9 . The method of  claim 1  in which said aqueous amendment is a wastewater.  
     
     
         10 . The method according to  claim 9 , in which said wastewater is one or more of primary sewage, treated sewage, and leachate from said landfill bioreactor.  
     
     
         11 . The method of  claim 1 , wherein said landfill bioreactor comprises both aerobic and anaerobic sectors.  
     
     
         12 . The method according to  claim 1 , wherein said landfill biofiltration is combined sequentially or in parallel with a process of oxidative biofiltration on inert supports.  
     
     
         13 . The method according to  claim 12 , wherein said inert supports comprise organic and inorganic size-reduced construction and demolition wastes.  
     
     
         14 . The method of  claim 1 , in which one or more of waste cover, base materials, and former landfill gas wells are filled with non-waste material to serve for biofiltration.  
     
     
         15 . The method of  claim 1 , in which zones, rates and percentages of contaminant reduction by bioremediation are assessed and thence controlled by means relying on localization, at points in or above the waste, of gas contaminant concentrations relative to known inert gas or inert gas tracer inputs.  
     
     
         16 . The method of  claim 1  in which the overall degree of biofiltration is assessed by contaminant reduction measurement relative to known inert gas or inert gas tracer inputs at a single gas outlet location where all gas exiting the biofiltration is commingled and well mixed.  
     
     
         17 . The method of  claim 1  in which the overall degree of contaminant emission in gas exiting the process is assessed from contaminant concentration and flow of gas exiting the landfill biofiltration.