Removal of Ammonia-Nitrogen from Wastewater in Dragon Steel Corporation. Chen, Chan-Po June 27 th, 2018

Transcription

1 Removal of Ammonia-Nitrogen from Waste in Dragon Steel Corporation Chen, Chan-Po June 27 th, 2018

2 2 Contents 1. Introduction 1.1 Policy Development in Taiwan 1.2 Source of Ammonia in DSC 2. NH 3 -N pollutant reduction plan of DSC 2.1 Estimation of Possible Solutions 2.2 Removal of NH 3 -N from Coking Waste 2.3 Enhanced nitrification in activated sludge system 2.4 Response to Abnormal Waste 3. Conclusion

3 3 1. Introduction Impact of Ammonia Pollution NH 3 -N is a very important indicator in the evaluation of pollution level

4 4 1.1 Policy Development in Taiwan NH 3 -N in clean river < 0.5 mg/l less than 50% of rivers whose quality can meet the standard Petrochemical without high nitrogen < 20 mg/l EPA announced 2012 July 2014 July Chemical without high nitrogen < 20 mg/l Semiconductor Manufacturers < 30 mg/l 2016 Jan Science Park < 30 mg/l 2017 Jan NH 3 -N pollutant reduction plan 2018 Jan Chemical without high nitrogen < 20 mg/l

5 5 Introduction of DSC DSC is an integrated steel plant with an annual production capacity up to six million tons of crude steel and two million tons of coke The coking waste from DSC contains high NH 3 -N, which leads to the effluent with NH 3 -N > 100 mg/l By-product Plant Waste Treatment

6 6 1.2 Source of Ammonia in DSC The NH 3 -N concentration in coking waste is about 500 to 1000 mg/l. 1~2% N By-product Plant COG Ammonia 70~90% Coal Coke Oven Plant Coking Waste Coke

7 7 How to meet the ammonia nitrogen requirement? implement a NH 3 -N pollutant reduction plan since 2014 GOAL: effluent with NH 3 -N < 20 mg/l since Jan. 2018

8 8 2. NH 3 -N pollutant reduction plan of DSC 2.1 Estimation of Possible Solutions Solutions for NH 3 -N waste treatment Air Stripping Chemical precipitation method(map Precipitation) Biological nitrification- denitrification process Financial Cost Operation Reliability Engineering Feasibility Decision : the removal of NH 3 -N from coking waste enhanced nitrification in activated sludge process online analyzer, buffer basin and stripping equipment as backup

9 9 By-product Plant Crude COG Downcomer Spray Primary Cooler Electrostatic Tar Precipitator Exhauster H2S/NH3 Scrubber Light Oil Scrubber/ Stripper Clean COG Condensed Tar/liquor Separator COG Filter Precipitate Ammonia liquor Storage tank Water Stripped Enriched solution de-acidifier Vapor Claus Reactor Coking Waste Waste Treatment

10 % C Removal of NH 3 -N from Coking Waste (1/2) to add the NaOH into to install the ammonia still unit 1. adjust the ph to over 10, most NH 3 -N in would be present as NH 3, which can be easily stripped off by the ammonia still ~ 50 % of NH 3 -N is fixed ammonia (irremovable) NH 4 + NH With NaOH, fixed ammonia would be decomposed into free ammonia (removable) pkb ph ammonia/ ammonium equilibrium

11 Removal of NH 3 -N from Coking Waste (2/2) Crude COG Downcomer Spray Condensed Tar/liquor Separator Primary Cooler Filter Precipitate Electrostatic Tar Precipitator Ammonia liquor Storage tank Exhauster Stripped H2S/NH3 Scrubber Enriched solution de-acidifier Vapor Claus Reactor Light Oil Scrubber/ Stripper Mixer NaOH Vapor Clean COG Ammonia Still Waste Treatment After improvement, the NH 3 -N concentration in coking waste can be reduced to under 200 mg/l.

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13 13 Waste Treatment System of DSC Activated sludge Organic Matter Suspended Solid

14 Enhanced Nitrification in Activated Sludge System Nitrification in Aeration Basin Nitrification: NH 4 + (or NH 3 ) + O 2 NO 2 - (nitrite) NO 3 - (nitrate) Item NH 3 -N NO 3 - Effluent Standard (mg/l) < 20 < 50 Over 70% of NH 3 -N can be converted into NO 3 -

15 15 Comply with Effluent Standard Under the normal condition, the NH 3 -N would be largely reduced in by-product plant and activated sludge process. The NH 3 -N in the effluent under than 20 mg/l.

16 Response to Abnormal Waste Domestic Sewage Sewer Backwash Waste Coking Waste Abnormal >200mg/L Equalization Abnormal >100mg/L Normal ph Adjustment Aeration recycle sludge Clarifier Sand Filter Abnormal > 40 mg/l Ozone Oxidation Sludge Cake Dehydrator Thickener Waste Sludge Buffer Basin Stripping Facility Sludge Cake Dehydrator Thickener Sludge Industrial Waste Coarse Screen Normal Abnormal >20 mg/l Equalization Flocculation/ Coagulation Sedimentation Sand Filter Abnormal > 15 mg/l Effluent/Reuse Basin Natural River Runoff Waste Backwash Waste Return to Equalization Reuse

17 17 3. Conclusion (1/3) 1) Impact of ammonia on environment is serious 2) Taiwan EPA has gradually announced several NH 3 -N standards for industrial effluent since ) NH 3 -N Pollutant Reduction Plan since ) Target: NH 3 -N in DSC effluent could be less than 20 mg/l since January 2018 NH 3 -N Concentration Effluent Standard < 20 (mg/l)

18 18 3. Conclusion (2/3) 1) DSC, production capacity up to 2 million tons of coke 2) Before 2014, the production of coke would produce the high level of NH 3 -N coking waste. 3) To reduce the NH 3 -N concentration in the coking waste to add the NaOH into the to install the ammonia still unit Before Improvement After Improvement NH 3 -N Concentration In Coking Waste 500 ~ 1000 (mg/l) < 200 (mg/l)

19 19 3. Conclusion (3/3) 1) NO 3 - is a less harmful pollutant than NH 3 -N Over 70% of NH 3 -N can be converted into NO 3-2) online analyzers, buffer basin, and stripping facility as a backup

20 20 Fulfilled NH 3 -N Pollutant Reduction Plan in Oct Currently, the NH 3 -N in DSC effluent is steadily lower than 15 mg/l. Effluent Standard Daily Average in DSC NH 3 -N Concentration < 20 (mg/l) 9 (mg/l) All effluent from DSC would comply with the legal standard

21 Thank for your attention 21