CITY OF STEUBENVILLE, OHIO WASTEWATER TREATMENT FACILITY

Transcription

1 CITY OF STEUBENVILLE, OHIO WASTEWATER TREATMENT FACILITY PAA Pilot Demonstration to determine PAA Efficacy as an alternative disinfectant to Chlorine and Sodium Bisulfite technology for wastewater Authors Mr. Chuck Murphy Assistant Superintendent Steubenville Waste Water Treatment Plant Robert Freeborn Vice President Sales and Marketing PERAGreen Solutions Jacquelyn Wilson PERAGreen Solutions

2 CITY OF STEUBENVILLE, OHIO WASTEWATER TREATMENT FACILITY PAA Pilot Demonstration to determine PAA Efficacy as an alternative disinfectant to Chlorine and Sodium Bisulfite technology for wastewater TABLE OF CONTENTS: Section 1: Executive Summary Section 2: Background Section 3: Disinfection Demonstration Protocol Section 4: Pilot Disinfection Demonstration Results and Conclusions Section 5: Bypass Disinfection June 2013 Section 6: Attachments and Data - A City of Steubenville Wastewater Plant Flow Diagram - B Alloway Report of Acute Biomonitoring - C Ohio River Water Sampling

3 Section 1 Executive Summary The City of Steubenville Wastewater Facility was prepared for a PAA Pilot disinfection demonstration beginning, March 26, A conceptual proposal was prepared on March 7, 2011 to evaluate Proxitane WW-12 on both Capture and Event occurrences during wet weather incidences in September A full report was issued based on this data and subsequent flow studies to correct hydraulic anomalies with the under and overflow weirs. The current demonstration was focused on the secondary discharge stream only and the findings are presented in this report. The results of a Bypass event are also discussed in this report demonstrating the effectiveness of Proxitane WW-12 with contact time before discharge as little as 9.26 minutes. The Proxitane WW-12 secondary demonstration began Monday, March 26, 2012 with results summarized in the following report. The pilot demonstration was extremely successful with expected PAA consumption and pathogen destruction from the injection point, through the contact chamber and ultimately to the river discharge. Pathogen, Fecal Coliform, levels of <10 CFU s/100 ml were achieved at the final outfall at a feed rate of 1.5 ppm of active PAA. Dosages were lowered throughout the demonstration to determine the lowest feed rate and PAA residual necessary to meet both summer and winter Fecal Coliform permit levels. The study continued until April 30, 2012 and then switched back to chlorine (15% liquid bleach) and dechlorination (sodium bisulfite) to provide head to head treatment evaluations for both technologies. In summary, chlorine bleach and sodium hypochlorite could attain the same pathogen destruction but at levels far in excess as compared to peracetic acid making Proxitane WW-12 more cost competitive. The Ohio EPA was asked to extend the approved use of Proxitane WW-12 through April 30 and then until the end of June 2012 to further evaluate improved feed and control to fine tune product dosage requirements. The results of the entire demonstration are outlined in this report. The Bypass study performed on June 13, 2013 demonstrated that with fecal coliform levels as high as 670,000 CFU s/100 ml and PAA residual levels of 0.6 ppm in the effluent stream, discharge fecal coliform levels were 440 CFU s/100 ml for a 4 log reduction in 9.26 minutes. In summary, Proxitane feed rates could be set at ppm with PAA residuals at levels down to 0.32 ppm in the final discharge and meet all NPDES permit pathogen requirements. Further tests conducted in June 2012 were designed to improve Proxitane WW-12 feed using modified pump controls to narrow the residual needed

4 for maximum pathogen kill. It was also shown that with direct feed into the bypass chamber, PAA could dramatically reduce pathogen contamination in the effluent stream. Section 2 Background Proxitane WW-12 is an environmentally friendly stable equilibrium of peracetic acid (12%), acetic acid (15%), hydrogen peroxide (18.5%) and water. Peracetic acid has a proven record as a safe sanitizer in the food industry. It is used in the municipal market primarily as a cost effective replacement for chlorine gas and sodium hypochlorite (bleach) followed by dechlorination with sodium bisulfite of sulfur dioxide gas.

5 There are no special handling requirements for Proxitane WW-12 but proper safety precautions are always important with dealing with any acid. Proxitane WW-12 Benefits Environmentally Green Product Cost effective compared to Chlorine/Dechlorination No known resistant organisms Long term efficacy Decomposes into non-harmful trace by-products (acetic acid, water, oxygen and trace amounts of organic acids) Final decomposition products are carbon dioxide and water Non-halogenated Forms no AOX Ready-to-use liquid Rapid Reactions In-pipe treatment Long term stability (12-18 month shelf life with no degradation) Equally effective in turbid and high solids waters No degradation by organics or ammonia Very stable in ambient temperatures Effective over the 5-8 ph range Low capital investment No dechlorination or deactivation step

6 Section 3 Disinfection Demonstration Protocol The City of Steubenville wastewater treatment plant is capable of processing up to 36 (MGD) million gallons of wastewater and storm water per day. Total plant capacity through the secondary treatment system is 13.5 MGD. Nominal daily flow is 6 MGD and dry weather flow 4 MGD. The focus of this demonstration is to treat both wet and dry conditions from March 26 through April 30 only on the secondary treatment system. Please refer to the plant diagram in ATTACHMENT A. PERAGreen Solutions conducted background demand and efficacy tests on primary and secondary streams at the City of Steubenville wastewater facility prior to the onsite evaluation beginning March 26, The uptake tests helped determine the starting PAA dosage required to meet NPDES discharge limits for Fecal Coliform to meet winter and summer geometric means. Two (2) 3010 pound totes of Proxitane WW-12 were set above the mixing chamber and connected to a Walchem IX Series metering pump. The Walchem pump skid was designed to feed based on totalized flow from both the North and South contact chambers. The PAA was fed into a manhole, directly into the discharge pipe from the three (330,000 gallon) secondary clarifiers, twenty five (25) feet upstream from the contact mixing chamber. The Walchem pump was adjusted to feed at 3.65 gallons per hour at a flow of 7 million gallons per day or at a rate of 1.5 ppm active PAA.

7 Sampling Locations, Monitored Parameters, Monitoring Frequency and Methods Fecal coliform densities were measured at one recordable sampling location, the final effluent discharge from the combined North and South contact chambers. Two other sites (mixing chamber and ¾ point) were measured intermittently to provide additional data on PAA performance between the injection point and the final discharge into the Ohio River. Measurements included fecal coliform and PAA (indirectly through DPD Total Chlorine residual measurement). Effluent flow is based on totalized water meter readings from both the North and South chlorine contact chambers. The three (3) test locations to determine residual PAA levels in the wastewater stream are outlined below in the attached chlorine contact chamber diagram found on the following page.

8 Inlet Mixing Chamber ¾ Test Point Discharge

9 The demonstration criteria were as follows: 1. Inject Peracetic Acid (Proxitane WW-12) neat, directly into the secondary clarifier combined discharge. At an initial feed rate of 1.5 ppm active PAA based on total flow. 2. Allow for adequate mixing in the contact chamber mixing chamber. 3. Test ¾ point PAA residuals once per day. Test final effluent discharge every two hours and record PAA residual and total flow. (The modified Hach, Low Level Total Chlorine test procedure was followed eliminating the 3 minute digestion and taking Total Chlorine readings in 15 seconds or less. The residual levels were then multiplied by 1.07 due to differences in reaction rate and specific gravity of the PAA.) Determination of LOW LEVEL Peracetic Acid (PAA) In Water Equipment and Reagents Chlorine, Total ( mg/l) Portable Colorimeter. Hach Model DR/890 DPD Total Chlorine Powder Pillows for 10 ml sample size. Hach Product number Sample cell, 10-ml. Procedure for Total Chlorine (Method 8167) USEPA approved for reporting water and wastewater analysis (USEPA Standard Method 330.5) B. DR/890 setup (1) Enter the stored program number for total chlorine (Cl2) powder pillows. (2) Press: PRGM. The display will show: PRGM? (3) Press: 9 ENTER. The display will show mg/l, Cl2 and the ZERO icon. B. Sample Testing (1) Fill a 10 ml sample cell with the PAA activated wastewater sample. This is the blank.

10 (2) Cap the blank cell and place it in the cell holder with the diamond mark facing you. Cover the cell compartment with the instrument cap to shield from stray light interferences and then press: ZERO. (3) The instrument will turn on and the display will show: 0.00 mg/l CL2. (4) Remove the blank cell (5) Immediately fill a second cell to the 10-ml mark with the PAA activated wastewater sample. (6) Add the contents of one DPD Total Chlorine Reagent Powder Pillow to the cell (prepared sample). Cap and swirl the sample cell vigorously to dissolve the powder. (It is not necessary that all the powder dissolves) (7) Insert the sample cell into the meter with the diamond mark facing you. Cover the cell compartment with the instrument cap to shield from stray light interferences. (8) Immediately Press: READ. The cursor will move to the right, then the result in mg/l total chlorine (Cl2) will be displayed. (9) This is the ppm total Cl 2 value. To calculate PAA, use the following formula: PAA Calculation ppm PAA = 1.07 x (ppm total Cl 2 PAA value) Multiply ppm total Cl 2 PAA value by 1.07 to express the result as ppm PAA based on the weight ratio of PAA to Cl 2 (76/71 = 1.07). 4. Test final effluent discharge for fecal coliform once per day on each of the North and South chambers and record. 5. Reduce PAA feed, record change in pump stroke and test residuals every two hours and fecal coliforms once per day. 6. Keep lowering PAA residuals until fecal coliform levels rise to winter discharge limits (1000 CFU s/100mil) and then increase pump stoke to maintain levels below summer limits of 200 CFU s/100ml continuously. Determine lowest PAA residual required to conform to discharge limits. 7. Maintain two hour fecal and flow monitoring until the Proxitane WW-12 is exhausted. 8. Once Proxitane WW-12 is empty, switch feed back to existing chlorine/dechlorination.

11 Criteria for Success The criteria for success were as follows: 1. Determine the lowest PAA levels required to meet summer NPDES discharge pathogen levels. 2. Successfully pass the WET test on the PAA treated discharge water with 0.4 ppm residual PAA. 3. Determine that flow pacing is an adequate method of feeding Proxitane WW Calculate cost effectiveness versus chlorine bleach and dechlorination using sodium bisulfite.

12 Section 4 Pilot Disinfection Demonstration Results and Conclusions Demonstration Summary Based on the pathogen and PAA residual tests conducted from March 26, 2012 through April 30, 2012 and comparing results to chlorine and dechlorination measurements immediately following the PAA demonstration, it was determined that Proxitane WW-12 outperformed chlorine and dechlorination on cost to achieve the same pathogen levels in the effluent discharge water from the secondary system. It was also determined from WET testing that the PAA residual level of 0.4ppm active PAA had no acute effect on selected fresh water organisms. The WET testing was performed by Alloway Laboratories on April 5-9, 2012 and the Report of Acute Biomonitoring was issued on April 19, The report is found in ATTACHMENT B. The organisms tested were neonate water fleas (Ceriodaphnia dubia) and fathead minnow larvae (Pimphales promelas). E.Coli tests were also conducted by Alloway on April 18, 2012 for secondary discharge and final effluent. The results are also shown in ATTACHMENT B. The demonstration results were as follows: 1. Proxitane WW-12 feed rates of ppm yielded PAA discharge residuals of 0.4 ppm. 2. CBOD testing remained constant without any impact on the effluent discharge stream. 3. Fecal Geomean was below NPDES permit levels when PAA residuals were maintained above 0.4 ppm. (Please refer to the Permit to discharge issued June 21, 2010 found on the CD supplied with the report) 4. Flow pacing was verified to provide the proper Proxitane WW-12 feed rate to achieve PAA residuals for pathogen destruction. General Discussion Prior to the start of the Proxitane WW-2 demonstration, dye testing was performed on the chlorine contact chamber as well as the effluent into the Ohio River. The tests were performed to identify the contact time at various flows as well as visually determine the discharge plume into the Ohio River. Videos were taken at both locations and are

13 included on the disk provided. The following picture demonstrates the minimal effect of flow near the river s edge as the effluent stream discharges into the Ohio River. In addition to dye testing, PAA residual and background total halogen testing was conducted on April 12, 2012 to determine the PAA residual in the discharge plume. The results of the testing can be found in ATTACHMENT C. It was concluded that the PAA remained in the plume entering the Ohio River approximately 25 feet offshore before any substantial dilution occurred. Once the discharge plume contacted the main flow of the river, the PAA dissipated quickly. Proxitane WW-12 Demonstration The Proxitane WW-12 Demonstration was initiated Monday, March 26 with the bleach and sodium bisulfite feed being shut down and isolated to allow for PAA to be fed prior to the final chlorine contact chamber. Proxitane WW-12 residuals and flow were recorded every two hours during the demonstration and the results are shown in the following graph.

14 GEOMEAN Fecal Coliform (CFU's/100ml) Fecal Coliform (CFU's/100ml) PAA Residual (ppm) Fecal Coliform vs. PAA Outfall Residual 1, , Daily Testing Fecal Coliform PAA Residual It is apparent from the graph that as PAA residuals were maintained above 0.4 ppm, fecal levels remained BELOW summer discharge limits. As PAA residual levels were reduced, correspondingly, fecal levels increased as seen during daily tests 8 through 14. Daily average effluent flow rates ranged from 3.59 to 5.99 MGD and secondary discharge fecal coliform levels ranged from ,000 CFU s/100 ml. The raw data can be found on the CD supplied with this report as well as the daily, two hour testing for PAA residuals and flows. Geomean averages for fecal coliform versus average PAA residuals for the five weeks are also shown in the following graph. Fecal Coliform Deactivation PAA Residual (ppm) Fecal Coliform

15 It can be seen that throughout the PAA and chlorine/dechlorination evaluations, there were no changes in CBOD levels or TSS levels. In addition, even with spikes in fecal carryover from normal levels of CFU s/100ml to 52,000 CFU s/100ml, discharge fecal levels were still below summer limits of 200 CFU s/100ml. This demonstrates the ability of PAA to handle upsets in process conditions. The effective kill was also at a consistent 0.75 ppm PAA feed with no change in dosage required to achieve the results.

16 To substantiate the continued effectiveness of Proxitane WW-12, a similar spike in fecal levels were seen in May 6-11, 2013 when work was being performed on two of the three secondary clarifiers. Fecal levels climbed from 2000 to 290,000 CFU s/100ml in two days before finally dropping back to normal levels. Without changing PAA dosage, Summer discharge limits of 200 CFU s/ml were achieved.

17 Section 5 Bypass Disinfection June 2013 A Bypass event occurred on June 13, 2013 and lasted for over 2.5 hours. This was the first opportunity to demonstrate the effectiveness of PAA during a wet weather event and bypass after design modifications were made to the 133,000 gallon chamber. It was found in a PAA study conducted in August 2011, that the 133,000 gallon old chlorine contact chamber with over and underflow weirs was short circuiting. This was due to a breech in both overflow walls. The breech was a result of removing a 2 foot by 2 foot section of concrete at the floor of the chamber, between the three cells, allowing them to be cleaned after a wet weather event. Stainless Steel gates were installed to still allow for cleanouts but are closed during a wet weather event to allow for proper mixing and contact time in the chamber. Please refer to the diagram of the contact chamber shown on the next page. The June bypass event began overflow to the Ohio River at 2:24 AM. Effluent flow was recorded at 3.03 MGD. The event last for over 2.5 hours with flows ranging from MGD. PAA residuals were measured from ppm at the end of the event. PAA was fed via flow control and measured at each cell of the chamber to identify uptake of the PAA as it reacted with the raw primary overflow. Fecal levels were measured and a level of 670,000 CFUs/100ml was recorded at the beginning of the event. Contact times were also calculated ranging from 9.26 minutes to minutes once overflow occurred. Fecal levels were recorded on the effluent at 440 CFUs/100ml with a contact time of 9.26 minutes. Further modifications in mixing will be addressed to improve PAA contact with the bypass overflow to the contact chamber and more data will be collected during bypass events.

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19 Results and Conclusions 1. Proxitane WW-12 effectively controlled effluent fecal coliform at a 0.4 ppm PAA residual to meet both summer and winter NPDES permit requirements. 2. WET testing concluded that at the 0.4 ppm PAA residual level, there was no effect on selected organism survivability in the discharge stream. 3. PAA could achieve fecal coliform discharge limits even al lower PAA residual dosages down to 0.32 ppm with improved chemical feed control. 4. Flow pacing is the desired method of feed and control of Proxitane WW- 12 feed independent on incoming fecal coliform levels from the secondary system. 5. Proxitane WW-12 was cost competitive versus chlorine (bleach) and dechlorination (sodium bisulfite) by a minimum of 25%. 6. Proxitane WW-12 was extremely effective in handling upsets in secondary discharge fecal levels up to 290,000 CFUs/100ml without any change in the low PAA dosage of 0.75 ppm. 7. Proxitane WW-12 is effective in treating wet weather flow with bypass flows up to and exceeding MGD without deactivation.

20 Attachment A City of Steubenville Wastewater Treatment Facility

21 B Attachment B

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30 ATTACHMENT C Proxitane WW-12 Ohio River Water Sampling Proxitane WW-12 - Ohio River Sampling PAA Residual (ppm) Outfall Outfall Upstream Outfall Outfall Downstream D.O. Temp Flow PAA Date Test Time 12-15' 0' Out 5.6' Out 10-12' ppm ph C MGD (ppm) 4/11/ :41PM :04PM :41PM :04PM /12/ :02PM a 4:07PM :10PM :15PM :20PM :10PM :15PM :20PM :25PM * All samples collected 5-6' from river bank