The Experimental Study Of Nitrogen Removal From The Coke Plant Wastewater By A~2/O~2 Process Of Utilizing Preponderant

Coke plant wastewater is a typical,containing high concentration ammoniacal nitrogen,and difficult biodegradational industry wastewater. Because coke sewage contains lots of hard-biodegraded and toxicant substances, it is considered to be one of the most difficult industrial waste water to purify. Drainage of coke sewage without purify could result in the serious pollution in waterbody,and the purified coke sewage that could not reach standard would also do harm to waterbody.With the physical or chemical process,which could meet the request of drainage for the environmental protection,the cost would be very expensive.Therefore,it is imperative to develop a kind of coke-plant wastewater treatment,which should be economically and technically feasible. According to characteristic of the coke plant wastewater,this paper studied utilizing the preponderant's mechanism and effect detailedly by A²/O² process to treat the coke wastewater of the second coke plant which belongs to taiyuan coal gas company.Experimental results demonstrate:the average removal rate of the Ammoniacal-nitrogen could reach 98.29%,and the denitrification rate could reach 79.46%,while the influent COD concentration was 817.4 mg/L～1874.2 mg/L,Ammoniacal-nitrogen concentration was 144.36mg/L～687.93mg/L,pH value was 7.0～8.22,and under the 3.27 refluent ratio,60.15 hours HRT,8.98g NaHCO₃ adding weight daily,averagely.These results showed the nitrogen removal effect was excellent. The experimental results showed that the A₁ reactor effluent Ammoniacal-nitrogen,nitrate-nitrogen and nitrite-nitrogen when nitrogen were 144.36～687.93mg/L could achieve 344.51 mg/L,1.16mg/L,0.042mg/L respectively in 8.41 hours,under the conditions of pH=7.0～8.22, temperature=29.6℃and DO≤0.2mg/L.The A₂ reactor effluent nitrogen,nitrate-nitrogen and nitrite-nitrogen when nitrogen were 105.23～677.78mg/L could achieve 109.45 mg/L,2.08mg/L,0.716mg/L respectively in 7.93 hours, under the conditions of pH=7.0～8.22,temperature=29.6℃and DO≤2mg/L. The O₁ reactor effluent Ammoniacal-nitrogen,nitrate-nitrogen and nitrite-nitrogen can achieve21.90 mg/L,13.09mg/L,0.14mg/L respectively in 18.49 hours,under the conditions of pH=6.40～8.14,temperature=29.1℃and DO≤1mg/L.The O₂ reactor effluent Ammoniacal-nitrogen,nitrate-nitrogen and nitrite-nitrogen can achieve12.98 mg/L,13.03mg/L,0.27mg/L respectively in 14hours,under the conditions of pH=5.82～7.97,temperature=24.7℃～29.1℃and DO≥2mg/L.Using Matlab,we calculated the effluent concentration of nitrogen and nitrate-nitrogen while the process operated stale and long-term:The effluent Ammoniacal-nitrogen average concentration point estimation of A₁ reactor was 344.50mg/L,the probability was 1 and the confidence interval was[263.78, 425.23]mg/L;The effluent Ammoniacal-nitrogen average concentration point estimation of A₂reactor was 113.93mg/L,the probability was 1 and the confidence interval was[76.21,151.65]mg/L;The effluent nitrogen average concentration point estimation of O₁ reactor was 21.86mg/L,the probability was 1 and the confidence interval was[11.75,31.97]mg/L,The effluent nitrate-nitrogen average concentration point estimation of O₁ reactor was13.08mg/L,the probability was 1 and the confidence interval was[8.79, estimation of O₂ reactor was 12.98mg/L,the probability was 1 and the confidence interval was[3.82,22.15]mg/L,The effluent nitrate-nitrogen average concentration point estimation of O₂ reactor was13.03mg/L,the probability was 1 and the confidence interval was[8.80,17.26]mg/L.The effluent ammoniacal-nitrogen,concentration from system of A²/O² could reach the first national standard about wastewater discharge (GB8978-1996).The ammoniacal nitrogen was less than 15mg/L.This technology is technique feasible,effect stable,and economic.