Low-impact delivery system for in situ treatment of contaminated sediment

Abstract

An agglomerate for use in economical bulk treatment of contaminated sediments with minimal environmental impact is formed from a sorbent, bentonite clay and sand. The agglomerate has sufficient density so as to sink through a water column into sediment below the water column and is still sufficiently light as to be capable of mixing with the sediment when subjected only to bioturbation. The agglomerate can be formed into pellets and applied to a water column over contaminated sediment by broadcast methods, so as to permit economical remediation of contaminated sediment with negligible environmental impact.

1 - 21 . (canceled) 
     
     
         22 . An agglomerate for treating contaminated sediments beneath a body of water comprising:
 a sorbent and a binder;   said sorbent and said binder being agglomerated into particles;   said particles being dense enough to sink in water without re-suspension in the water of said sorbent after said agglomerate particles are distributed on a surface of a body of water over contaminated sediment;   said particles breaking down in sediment beneath the body of water under only the influence of bioturbation;   whereby said sorbent is exposed to contaminants in the sediment, beneath the water.   
     
     
         23 . The agglomerate of  claim 22  further comprising a dense element being agglomerated in said particles. 
     
     
         24 . The agglomerate of  claim 23  further comprising said dense element being sand. 
     
     
         25 . The agglomerate of  claim 22  further comprising said sorbent being activated charcoal carbon. 
     
     
         26 . The agglomerate of  claim 22  further comprising said binder being bentonite. 
     
     
         27 . The agglomerate of  claim 22 , wherein said particles contain about 30% to about 80% sorbent. 
     
     
         28 . The agglomerate of  claim 22 , wherein said particles contain about 10% to about 30% bentonite clay. 
     
     
         29 . The agglomerate of  claim 22 , wherein said binder is bentonite clay, said sorbent is powdered activated carbon and said bentonite clay does not inhibit the ability of said powdered activated carbon in the agglomerate to absorb iodine. 
     
     
         30 . The agglomerate of  claim 22 , wherein the particles contain about 60% powdered activated carbon, about 20% bentonite clay and about 20% sand. 
     
     
         31 . The agglomerate of  claim 22 , wherein the particles contain about 0% to about 40% sand. 
     
     
         32 . The agglomerate of  claim 22 , and further comprising a binder having negligible toxicity to the benthic organisms so as to be suitable for repeat application to the same water column if desired. 
     
     
         33 . The agglomerate of  claim 22 , further comprising said particles having cellulose. 
     
     
         34 . The agglomerate of  claim 22 , further comprising said break down of said agglomerate delivering said sorbent to a bioactive zone of sediment for sorption of contaminants. 
     
     
         35 . The agglomerate of  claim 22 , further comprising said agglomerate producing no more than one percent by weight of fines when the agglomerate is rolled for one hour at four rpm. 
     
     
         36 . The agglomerate of  claim 22 , wherein said particles are formed in the size range of about 1 mm to about 15 mm in diameter. 
     
     
         37 . The agglomerate of  claim 22 , wherein said particles have a length of up to about 100 mm. 
     
     
         38 . The agglomerate of  claim 22  further comprising said particles having a consistency of about 55% powdered activated carbon, about 25% bentonite, about 15% sand and about 5% cellulose. 
     
     
         39 . The agglomerate of  claim 22  further comprising said particles having a consistency of about 60% powdered activated carbon, about 20% bentonite and about 20% sand. 
     
     
         40 . The agglomerate of  claim 22  further comprising said sorbent treating metal contaminants from the sediment. 
     
     
         41 . The agglomerate of  claim 22  further comprising said sorbent treating organic contaminants from the sediment. 
     
     
         42 . The agglomerate of  claim 22  wherein said sorbent is exposed to contaminants in a benthic zone of the sediment wherein mixing by bioturbation takes place. 
     
     
         43 . The agglomerate of  claim 22  wherein said particles have a density insufficient to penetrate bottom sediment after sinking so that said particles are available to be mixed by bioturbation. 
     
     
         44 . The agglomerate of  claim 22  wherein said particles settle on a surface of the sediment. 
     
     
         45 . The agglomerate of  claim 22  wherein said sorbent is exposed to contaminants in a biologically active zone of the sediment where bioturbation occurs. 
     
     
         46 . The agglomerate of  claim 45  wherein said biologically active zone of the sediment is substantially about 6 inches deep. 
     
     
         47 . The agglomerate of  claim 45  wherein said biologically active zone of the sediment is substantially about 2 inches deep. 
     
     
         48 . The agglomerate of  claim 44  wherein said particles form a light, non suffocating and temporary layer on the sediment and said particles are broken down and mixed by bioturbation. 
     
     
         49 . The agglomerate  claim 33  wherein said cellulose acts as a degradable binder to hold the particle together during application. 
     
     
         50 . The agglomerate of  claim 22  wherein said particles are pellets. 
     
     
         51 . The agglomerate of  claim 22  wherein said particles sink to a region where bioturbation occurs.