Abstract Method and apparatus for denitrification of aqueous nitratecontaining solutions. Specifically the invention provides for denitrification of the effluent from an activated sludge sewage treatment process. Effluent from the settling zone of an activated sludge sewage treatment process containing nitrogen compounds such as nitrates and nitrites, is passed through a deep bed filter, the filter media of which has been innoculated with bacteria that converts the nitrogen compounds to nitrogen gas. The filter, in addition to removing the nitrogen compounds, removes any suspended solids from the settling zone effluent, so that the final effluent from the filter is concurrently clarified and denitrified. By controlling the backwash of the filter, bacteria is retained thereon so as to enable continuous use of the filter for denitrification.
An activated sludge sewage treating plant as defined in claim 1 wherein said filter contains a colony of anerobic bacteria within said housing, said bacteria capable of converting nitrates in said effluent to gaseous nitrogen.
Claim 2
Dependent Claim
34 words
An activated sludge sewage treating plant as defined in claim 2 including means for charging a carbon source into the effluent from said settling zone prior to introduction of the effluent into the filter.
Claim 3
Dependent Claim
28 words
An activated sludge sewage treating plant as defined in claim 2 including means for heating the effluent from said settling zone prior to introduction thereof into the filter.
Claim 4
Dependent Claim
61 words
An activated sludge sewage treating plant as defined in claim 2 wherein said means for intermittently backwashing said filter comprises means for forcing water into the bottom of said housing and upwardly through the reticulated bottom and filter bed and means for removing the backwash water from the top portion of the housing and returning the same to said aeration zone.
Claim 5
Dependent Claim
48 words
An activated sludge sewage treating plant as defined in claim 5 including means for diverting a portion of said backwash water, after removal from the filter and prior to return to the aeration zone, into said charging means for introducing effluent from said settling zone into the filter.
Claim 6
Dependent Claim
54 words
An activated sludge sewage treating plant as defined in claim 3 wherein said means for intermittently backwashing said filter includes means for forcing a major portion of water into the filter housing at a position above said reticulated bottom and means for forcing a minor portion of water into the bottom of said housing.
Claim 7
Dependent Claim
31 words
An activated sludge sewage treating plant as defined in claim 7 wherein the majority of the particles in the bed vary in size less than about 1 mm from each other.