1.
 Nitrite Accumulation Characteristics in the Nitrificationof High Strength Ammonia Wastewater with Biofilm Airlift Suspension Reactor




 


 
  

       

   !"

* ^†

 

*  

(2001 8 3 , 2001 11 16 )

Nitrite Accumulation Characteristics in the Nitrification

of High Strength Ammonia Wastewater with Biofilm Airlift Suspension Reactor

Jae-Sun Chang, Gi-Cheol Cha* and Dong-Jin Kim^†

Department of Environmental Science, Hallym University, Chunchon 200-702, Korea

*Department of Environmental Engineering, Yonsei University, Seoul 120-749, Korea (Received 3 August 2001; accepted 16 November 2001)



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Abstract−Selective nitrifications of high strength ammonia wastewater was performed with biofilm airlift suspension reac- tor for the economical removal of nitrogen via nitrite. Biofilms were successfully attached on the surface of the carriers(sand) and the biomass concentration reached up to 15 g/L with the reactor. During the experiment more than 90% nitrification was obtained at 2.5 kg NH₄⁺- N/m³/d and selective nitrification was successfully carried out to have more than 90% nitrite accu- mulation of the total oxidized nitrogen. Nitrite accumulation was achieved by the inhibitions on nitrite oxidizers with free ammonia and low dissolved oxygen in the biofilm airlift suspension reactor. From the batch nitrification analysis it was shown that the existence of free ammonia is the main cause of nitrite accumulation.

Key words: Biofilm Airlift Suspension Reactor, Nitrification, Nitrite Accumulation, Nitrogen Removal

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†To whom correspondence should be addressed.

E-mail: dongjin@hallym.ac.kr

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Fig. 1. Schematic experimental setup of the biofilm airlift suspension reactor.

Table 1. Experimental conditions of biofilm airlift suspension reactor

Period Experiment I Experiment II

A B a b c d

Operation(days) 1-46 47-147 1-37 38-63 64-131 132-150

NH₄⁺- N(mg/L) 500 500 500 500 500 500

NH₄⁺- N load(kg N/m³·d) 2.0 2.5 2.5 2.5 2.5 2.5

Air flow rate(L/min) 2.5 2.5 2.5 3.0 2.5 3.5

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NO₂⁻–N

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NO₂⁻–N

[ ]+[NO₃⁻–N] --- Table 2. Experimental conditions of batch nitrification kinetic analysis

Condition Batch test of AO and NO

AO medium NO medium

NH₄⁺- N(mg/L) 100 0

NO₂⁻- N(mg/L) 0 100

Wastwater: trace elements 1:1 1:1

MLVSS(g/L) 1.5 1.5

Mixing velocity(rpm) 100 100

Initial pH 7.2 7.2

Temperature(^oC) 28 28

Medium amount(mL) 400 400

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ö A 2 Ì%á$. {|U free ammonia ‰o% ’6Fg Fig. 2. Electron micrographs of nitrifying bacteria.

(A) Sand as biofilm media(SEM, ×800). (B) Nitrifying biofilm on the media(SEM, ×600). (C) Nitrifying biofilm on the media, as granule(SEM, ×200).

(D) Nitrifying bacteria(TEM, ×110,000)

Fig. 3. Mixed liquor volatile suspension solid profile of the biofilm airlift suspension reactor.

 40 1 2002 2

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yK 2.5 L/minC8 m– ш$. #q WX ã 0 1 ‰ o F`!C8 m T(U FçK ´  $. # {| 1 Fig. 4. Effect of NH₄⁺- N load on nitrification in the biofilm airlift sus-

pension reactor.

(
: NH₄⁺- N; _: NO₂⁻- N; _: NO⁻₃- N; _: nitrification efficiency;

:

NH₄⁺- N load)

Fig. 5. Effect of air flow rate on nitrification in the biofilm airlift sus- pension reactor.

(
: NH₄⁺-N; : NO₂⁻- N; : NO
⁻- N; : nitrification efficiency;

:

air flow rate)

Table 3. Effect of dissolved oxygen concentration on the nitrification of the biofilm airlift suspension reactor

Period ..

Characters a b c d

Nitrification efficiency(%) 85 95 82 97

Nitrite ratio 0.83 0.79 0.95 0.96

Dissolved oxygen concentration(mg/L) 1.8 2.6 1.2 2.7

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Fig. 6. Batch nitrification kinetic analysis of nitrite accumulating bio- mass from the biofilm airlift suspension reactor[(A): ammonia oxidation, (B): nitrite oxidation].

(
: NH₄⁺- N; _: NO₂⁻- N;_: NO⁻₃- N)

 40 1 2002 2

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