City of Woodbury Red Bank Water Treatment Plant - Treatment Alternatives Analysis November 2016
Background • Remington & Vernick was authorized to study and design a treatment process for removal of PFC (Perfluorinated Chemicals) including PFNA, PFOA, and PFOS. • Consideration was also given to review of treatment for chromium removal. • The treatment process to be constructed at the existing Red Bank Water Treatment Plant which currently treats water for Well No. 7 & Well No. 8, • Prior to design selection, evaluate treatment options for the removal of PFNA, PFOA, PFOS and potentially chromium.
Basis of Evaluation • Effectiveness of treatment for PFCs and/or chromium; • Construction Costs including any building modifications; • Costs of treatment system and start up media; • Anticipated life span of media and replacement costs; • Energy costs of improvements; • Operational Costs o Backwash /regeneration requirements; o Wastewater generation and disposal (GCUA fees); o Routine testing requirements to operate system; o Staffing requirements to run treatment system
Treatment Alternatives • Reverse Osmosis (RO) • Ion Exchange Process • Granular Activated Carbon Filtration (GAC)
Reverse Osmosis General Process – Effective process for removing multiple contaminants from water stream including PFNA, PFOA, PFOS and chromium. – The process forces water thru a series of thin membranes while filtering out contaminants. – Complicated process where membranes are prone to fouling and degradation. – The membranes require a very high quality feed water to be efficient. Therefore, pretreatment is often required. – Would require building modifications / expansion.
Reverse Osmosis Operational Overview – Requires pre-treatment prior to entering membranes. – In fact, this will require additional iron and manganese beyond what the existing greensand plus filters already remove. – Chlorine causes filters to degrade. Therefore, dechlorinating will be necessary prior to entering filters. – Pre-filtration will be required prior to water entering the filters. – Scale inhibitor will be required prior to water entering the filters.
Reverse Osmosis Maintenance Overview – Build up occurs on membrane surfaces which causes a loss in the flow thru the membrane. – Membranes will require cleaning every 3-6 months. – A constant highly concentrated waste stream is produced – approximately 15-25% of water is lost during process. – The waste stream is a concentrated brine solution containing high concentrations of sodium, chloride, and dissolved solids. – A GCUA Industrial Pretreatment Permit would be required and a surcharge for concentrated waste would be enacted – if waste is accepted by GCUA. – GCUA may require pretreatment of waste due to TSS concentrations
Reverse Osmosis Maintenance Overview Continued – Each membrane has a life expectancy of 2-5 years. Total costs for all membranes to be replaced $330,750. – Cartridge pre-filters – approximately $4,500 annually for replacement costs.
Reverse Osmosis Summary of Requirements: Construction • Building expansion; • Pretreatment Filtration and addition of high service pumps • Dechlorination via sodium bisulfate • Sulfuric acid for pH adjustment • Addition of scale inhibitor Operation & Maintenance • Constant waste stream / loss of water at 150-250 gpm • Industrial Pretreatment Permit and fee from GCUA. May require pre-treatment of waste stream. • Additional chemical costs, energy costs, and T3 operator • Anticipated replacement of RO membranes every 3 years
Reverse Osmosis Estimated Fees
Ion Exchange General Process – Effective at removing some portions of PFOA and PFOS and to a lesser extent, PFNA. – The process forces water thru a pressure vessel filled with resin specially design to allow chemical stripping of the PFC chains. – Resin requires regeneration based upon concentration of PFC’s – approximately 1 to 2 times per week. – Regeneration is usually completed thru addition of an acid or brine; requiring chemical addition AND neutralization of regeneration water. – Would require building modifications
Ion Exchange Operational Overview – Frequent regeneration with acid or brine which creates a waste stream that will require disposal. – The addition of this treatment process will not impact the current T2 license requirements.
Ion Exchange Maintenance Overview – Build up occurs on resin and the resin must be “cleaned” 1 to 2 times per week. – The process will require purchase of chemicals for regeneration; most likely a weak acid or brine solution. – The waste stream generated from regeneration will require neutralization; requiring additional chemicals. – Disposal to GCUA will require a permit and additional fees..
Ion Exchange Summary of Requirements: Construction • Building expansion; • Addition of chemical storage for regeneration; • Addition of neutralization system for regeneration waste. Operation & Maintenance • Industrial Pretreatment Permit and fee from GCUA. May require pre-treatment / neutralization of waste stream. • Additional chemical costs • Anticipated replacement of resin membranes every 10-12 years.
Ion Exchange Estimated Fees
Granular Activated Carbon (GAC) General Process – Adsorption system designed for the removal of organic contaminants including disinfection byproducts. Does not adsorb chromium. – Carbon is the most effective treatment process for removing PFC’s. – The process forces water thru two pressure vessels installed in series. The two vessels provide the required 20 minutes contact time required by NJDEP. – Backwash will be required when there is a pressure change across the bed. Anticipated to be every 2-3 months.
Granular Activated Carbon (GAC) Operational Overview – Must be installed after the existing greensand plus filters since iron will clog the GAC units. – Backwash of the filters will be required every 2-3 months; based upon suspended solids in the raw water. The backwash will initiate automatically; based upon change in pressure. – Chlorine will be adsorbed on the carbon media. Therefore, post filter chlorine addition will need to be modified. – The addition of the carbon filters will change the operator requirements from T2 to T3.
Granular Activated Carbon (GAC) Maintenance Overview – Typical carbon replacement will occur every 2-3 years. The price for carbon replacement will depend upon the carbon selection. – Typical costs to replace carbon in similar size vessels range from $100,000 to $150,000. – Total Organic Carbon will break thru the carbon filters before PFC’s. Therefore, the detection of TOC will indicate that the carbon will need to be replaced.
Granular Activated Carbon (GAC) Types of Carbon – Coconut Shell – • Not effective at PFC removal. – Filtersorb 400 – • coal based carbon – typically $1.25/lb. • Can be re-generated when spent and save the City $0.5 per pound during replacement • Leachable products in coal based carbon- typically miniscule amounts. • Raises pH for the first 50-100 bed exchanges.
Granular Activated Carbon (GAC) Types of Carbon - continued – Filtersorb 400 AR – • Same coal based carbon except it is was in acid prior to delivery for removal of the leachables. • Can be re-generated when spent and save the City $0.5 per pound during replacement • Is more expensive - $1.75 per pound vs. $1.25 per pound • Raises pH for the first 50-100 bed exchanges. – pH Stabilized - • As an option, there is a pH stabilized coal based carbon that is approximately $1.50 per pound.
Reverse Osmosis Summary of Requirements: Construction • Building expansion; • Install after greensand plus filters Operation & Maintenance • Automated backwash when there is a pressure change of 10 psi across the carbon bed • Additional T3 operator costs • Anticipated replacement of carbon every 3 years
Granular Activated Carbon Estimated Fees
Recommendations It is recommended that Granular Activated Carbon (GAC) Filters be selected as the treatment alternative based upon: – Effective removal of PFNA, PFOA and PFOS. – Minimal operational requirements in terms of backwash and testing. – Most cost efficient from a construction and annual maintenance perspective.
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