Abstract Sodium hypochlorite or chlorine is used to oxidize the ammonia in raw, secondary and lime clarified municipal wastewaters. In systems with only ammonia as the chlorine demand, the breakpoint exhibits a minimum chlorine dose at approximately an 8:1 weight ratio of Cl:NH3-N in the pH range of 6 - 7. End products at the breakpoint are N2, NCl3, and NO3 . Qualitatively, the formation of the N2 is completed in less than one minute in the pH range of 6 - 8. In wastewater, the breakpoint requires a minimum chlorine dose of approximately an 8:1 weight ratio of Cl:NH3-N in lime clarified secondary effluent. The chlorine dosage, to achieve the breakpoint increases as the degree of wastewater treatment decreases.
A method in accordance with claim 1 wherein said wastewater is a raw or primary wastewater and said ratio of Cl:NH3-N is maintained at about 10:1.
Claim 2
Dependent Claim
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A method in accordance with claim 1 wherein said wastewater is secondary or tertiary effluent or chemically clarified raw wastewater, and said ratio of Cl:NH3-N is maintained at about 8:
Claim 3
Dependent Claim
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A method in accordance with claim 1 wherein said chlorine material is free chlorine and is fed at the rate of about 120 -170mg./l.
Claim 4
Dependent Claim
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A method in accordance with claim 1 further comprising recycling a portion of the product leaving said mixer-reactor.
Claim 5
Dependent Claim
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A method in accordance with claim 1 wherein said chlorine material is free chlorine, and said pH is maintained at 6 - 8 by additionally feeding a stream of hydroxide to said mixer-reactor.
Claim 6
Dependent Claim
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A method in accordance with claim 6 further comprising recycling a portion of the product, and wherein said stream of chlorine, said stream of hydroxide and said recycled product are mixed prior to feeding to said mixer-reactor.
Claim 7
Dependent Claim
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END PRODUCTS AT THE BREAKPOINT ARE N2, NCL3, AND NO3. QUALITATIVELY, THE FORMATION OF THE N2 IS COMPLETED IN LESS THAN
Claim 8
Dependent Claim
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A method in accordance with claim 7 further comprising a preliminary partial chlorination wherein wastewater is mixed with a small amount of chlorine, followed by CO2 removal.