Rapid Infiltration System for Enhanced Removal of Nitrate from Middletown Secondary Effluent. Min Ho, Maeng

Transcription

1 Rapid Infiltration System for Enhanced Removal of Nitrate from Middletown Secondary Effluent Min Ho, Maeng

2 Current Effluent Discharge in Middletown Effluent discharge in Middletown Send to New Castle County water farm Increase in treatment capacity MGD MGD 0.4 MGD.63 Irrigation for Frog Hollow golf Sprayed on course farmland owned by Middletown Current Current Expansion Expansion by AS system Unit ; MGD Data from Town of Middletown Comprehensive Plan, Nov. 2005

3 Proposed Rapid Infiltration System Wastewater Activated Sludge System Secondary Effluent Rapid Infiltration System Groundwater Recharge Enhanced nitrogen removal prior to groundwater recharge

4 Schematic Diagram of Rapid Infiltration System Sandy Soil NO 3 - N 2 Groundwater table Saturated soil layer

5 Parameters Affecting Denitrification 5 Temperature Hydraulic loading rate ( < 60 lb/ac d) Carbon : N ratio 6 3 NO3 H e N2 H2O Type of electron donor Application/Drying cycle Small and Decentralized Wastewater Management Systems by Crites & Tchobanoglous 998

6 Research Objectives Evaluate various potential electron donor to enhance denitrification in rapid infiltration system Determine the optimum loading/drying cycle and hydraulic loading rate for nitrate removal Evaluate the performance of optimized system under low temperature conditions

7 Soil Columns Set-up Nitrate Phosphate Flow rate Operation cycle 0 mg NO 3- -N/L mg PO P/L cm/hr 7 days application/0 days drying

8 Operation of Soil Columns Plexiglas Soil Columns (24 in long x 2 in dia.)

9 Substrates Preparation Solids substrates - Wood chips, compost - : volume ratio

10 Substrates Preparation Liquid substrates (for reduction of 0 mg NO 3- -N/L) - For methanol 6 CH OH 3 5 NO 3 5 H 0 N H 2 O 6 CO 2 - For molasses C6H 27 2 NNaO S 3 5 NO 3 5 H 0 N H 2 O 27 HCO 3 24 NH CO 2 Stoichiometric value Column Influent Methanol 9. mg/l 38 mg/l Molasses 26.6 mg/l 53 mg/l

11 Nitrate (mg NO 3 - -N/L) Nitrate Removal in Soil Columns Influent Control Methanol Molasses Wood Chips Compost Experimental Day

12 Nitrate (mg NO 3 - -N/L) Nitrate from Sampling Ports Column height (cm) Control Methanol Molasses Wood Chips Compost Schematic diagram

13 TOC (mg C/L) Effluent TOC from Soil Columns Control Methanol Molasses Wood Chips Compost Experimental Day

14 Phosphate (mg PO P/L) Phosphate Removal in Soil Columns Influent Control Methanol Molasses Wood Chips Compost Experimantal Day

15 Conclusions Enhanced removal of nitrate with substrate addition Rapid recovery of denitrification activity after 7-day resting period Efficient removal of phosphate High residual TOC in both solid and liquid substrate columns

16 Future Works Selection of optimum substrate large-scale RIB operation (ongoing) Soil column study with real secondary effluent - Real effluent from a local nitrifying plant Low temperature study - Test in the climate controlled room - 5 and 0 conditions Rapid Infiltration Basin Water Conserv II facility, Orlando, Florida Loading/drying cycle and hydraulic loading rate optimization study - Larger soil columns : ft dia. x 4 ft - Flow rate : and 5 cm/hr - Application periods : 5 and 0 days

17 Thanks to Dr. Daniel K. Cha (Research Advisor) Dr. William F. Ritter (co-advisor) Nathan Kiracofe Michael J. Davidson Doug Baker Funding provided by Town of Middletown

18 Questions?