PD-Sw205w 1 1 FOSNRS 2: Passive, 2-Stage Biofilter Treatment Systems for Reduction of Nitrogen from OWS – Pilot Study Results April 7, 2014 Josefin Hirst, P.E. The Florida Onsite Sewage Nitrogen Reduction Strategies (FOSNRS) Project SSSA Onsite Wastewater Conference April 7-8, 2014 Hazen and Sawyer, P.C.

PD-Sw205w 2 Presentation overview ■FOSNRS Task A: Nitrogen treatment and reduction options for Florida ■Pilot test results ■Summary ■Questions and answers

PD-Sw205w 3 3 FOSNRS Task A: Nitrogen treatment and reduction options for Florida

PD-Sw205w 4 Review of biological nitrogen reduction for onsite wastewater treatment Primary Treatment Mineralization of organic N to ammonia (NH 4) Nitrification Ammonia oxidized to nitrate (NO 3 ) by nitrifying bacteria, requires oxygen Denitrification Nitrate converted to N 2 gas by denitrifying bacteria in anoxic environment; requires supply of electron donor Dispersal Effluent discharge to the soil or landscape for final treatment

PD-Sw205w 5 What are “Passive” nitrogen reduction systems (PNRS)? ■Most current N-reducing onsite systems are mechanical treatment units, with pumps, blowers, controls ■Passive definition for this project: Passive nitrogen reduction systems (PNRS) are OSTDS that reduce effluent N using reactive media for denitrification and a single liquid pump, if necessary. ■Earlier work showed feasibility of bench-scale “passive” two stage biofiltration concepts (Smith et. al., 2008) Treatment Media Effluent TN (mg/L) TN Reduction (%) Zeolite & Sulfur Media2.297 Expanded Clay & Sulfur

PD-Sw205w 6 Task A was designed to further the concepts developed in previous work ■Developed detailed performance data for passive biofiltration designs with various media configurations ■Produced scalable design criteria from pilot scale biofilters for subsequent full-scale testing ■Evaluated single pass and recirculating stage 1 biofilters ■Evaluated twenty-two biofilters consisting of nine unsaturated Stage 1 biofilters, nine saturated Stage 2 biofilters, and four vertically stacked biofilter designs.

PD-Sw205w 7 A unique pilot facility was constructed at UF research center ■University of Florida, Institute for Food & Agricultural Sciences (IFAS) ■475 acres of land in SE Hillsborough County ■Facility conducts agricultural research & trials for vegetables, fruit and ornamental plants ■Experts in soil and water science onsite Source:

PD-Sw205w 8 Test facility included numerous treatment trains ■All used two-stage biofilters: ●Stage 1 Nitrification ●Stage 2 Denitrification ■Stage 1 unsaturated filters included 2 media layers and evaluated 15” and 30” media depths ■We also evaluated single pass and recirculating stage 1 biofilters ■For denitrification, we evaluated both lignocellulosic and sulfur denitrification biofilters

PD-Sw205w 9 Various nitrification media were studied Zeo-Pure clinoptilolite Expanded polystyrene Examples of Stage 1 Media Expanded clay Torpedo sand

PD-Sw205w 10 Various denitrification media were also studied Elemental Sulfur Lignocellulosics Examples of Stage 2 Media Oyster shell (alkalinity amendment)

PD-Sw205w 11 PNRS test facility construction Setting up tanks Mixing Media Batches Gravel Underdrain

PD-Sw205w 12 Placing media in tanks

PD-Sw205w 13 Two stage single pass biofilters Stage 1 HLR 3 gal/d-ft 2 Stage 2 HLR 5.6 gal/d-ft 2

PD-Sw205w 14 We tested five trains of two-stage single pass treatment units

PD-Sw205w 15 Two-stage single pass biofilters Stage 1 Unsaturated Biofilters - Nitrification Stage 2 Saturated Upflow Biofilters - Denitrification

PD-Sw205w 16 Stage 1 recirculating biofilters schematic Nitrified Effluent Holding Tank Stage 1 HLR 3 gal/d-ft 2 Recycle Ratio 3:1 Stage 1

PD-Sw205w 17 Horizontal stage 2 biofilters schematic Peristaltic Pump Sample Ports Nitrified Effluent Stage 2 HLR 10 gal/d-ft 2

PD-Sw205w 18 Four recirculating stage 1 trains were followed by four stage 2 horizontal biofilters

PD-Sw205w 19 Stage 1 recirculating biofilters & Stage 2 horizontal saturated biofilters Stage 2 Saturated Biofilters - Denitrification Stage 1 Unsaturated Biofilters - Nitrification Pump Tank Nitrified Effluent Pump Tank

PD-Sw205w 20 PD-Sw205w 20 Pilot test results

PD-Sw205w 21 PNRS pilot testing influent STE quality cBOD 5 TSSTNTKNNH 3 -N Total Alkalinity Septic tank effluent (STE) n mean std. dev min max

PD-Sw205w 22 Stage 1 nitrification biofilters mean effluent values BiofiltercBOD 5 TSSTNTKNNH 3 -N(NO 3 +NO 2 ) Single Pass XCLAY – 15” XCLAY – 30” CLINO – 15” CLINO – 30” Recirculating SAND – 30” XCLAY – 30” CLINO – 15” CLINO – 30”

PD-Sw205w 23 Stage 1 single pass biofilters nitrogen time series Single Pass Expanded Clay: 30 inch depthSingle Pass Clinoptilolite: 30 inch depth CLINO – 30”XCLAY – 30”

PD-Sw205w 24 Recirculating Expanded Clay: 30 inch depth Stage 1 recirculating biofilters nitrogen time series CLINO – 30”XCLAY – 30” Recirculating Clinoptilolite: 30 inch depth

PD-Sw205w 25 Stage 1 nitrification biofilters effluent nitrogen box and whisker plots XCLAY-15” XCLAY-30” CLINO-15” CLINO-30” XCLAY-30” SAND-30” CLINO-15” CLINO-30” XCLAY-15” XCLAY-30” CLINO-15” CLINO-30” XCLAY-30” SAND-30” CLINO-15” CLINO-30” Single PassRecirculatingSingle Pass Recirculating Ammonia Nitrogen, mg N/L Nitrate & Nitrite Nitrogen, mg N/L

PD-Sw205w 26 Stage 2 denitrification biofilters mean effluent values BiofilterC-BOD 5 TSSTNTKNNH 3 -N(NO 3 +NO 2 ) Upflow SULFUR-30% LIGNO-50% SULFUR-80% LIGNO-25% LIGNO-30% Horizontal SULFUR-80% SULFUR-30% LIGNO-50% GLYCEROL

PD-Sw205w 27 Stage 2 upflow single pass biofilters nitrogen time series SULFUR-80% LIGNO-50%

PD-Sw205w 28 Stage 2 horizontal biofilters nitrogen time series SULFUR-80%LIGNO-50%

PD-Sw205w 29 Stage 2 denitrification biofilters effluent nitrogen box and whisker plots Mean = 14.2 SULFUR-30% LIGNO-50% SULFUR-80% LIGNO-25% LIGNO-30% SULFUR-30% SULFUR-80% LIGNO-50% GLYCEROL SULFUR-30% LIGNO-50% SULFUR-80% LIGNO-25% LIGNO-30% SULFUR-30% SULFUR-80% LIGNO-50% GLYCEROL Upflow Horizontal Upflow Horizontal Nitrate & Nitrite Nitrogen, mg N/L Total Nitrogen, mg N/L

PD-Sw205w 30 Single pass systems total nitrogen removal SULFURLIGNOCELLULOSIC

PD-Sw205w 31 Recirculating systems total nitrogen removal SULFURLIGNOCELLULOSIC

PD-Sw205w 32 Vertical sampler profile in Upflow biofilters lignocellulosic issues

PD-Sw205w 33 Lignocellulosic biofilters hydraulic retention time issues

PD-Sw205w 34 Solute profile in sulfur upflow biofilter sulfate production vs nitrate reduction

PD-Sw205w 35 Single pass vs recirculating biofilters: sulfate

PD-Sw205w 36 Lessons learned from pilot test ■Encouraging results from pilot PNRS; several system configurations capable of > 95% N reduction ■Sulfate production vs nitrate reduction ■Highly reactive elemental sulfur media ■Lignocellulosic retention time issues ■Recommended evaluation of combination lignocellulosic and elemental sulfur denitrification systems for full-scale treatment units

PD-Sw205w 37 PD-Sw205w 37 Questions? Josefin Edeback-Hirst, P.E. Hazen and Sawyer, P.C Princess Palm Avenue, Suite 200 Tampa, FL