Micro-Contaminants: Sources, Controls and Treatment Methods
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Rural Community Assistance Partnership Practical solutions for improving rural communities Micro-Contaminants: Sources, Controls and Treatment Methods Neil Worthen, RDS Environmental Rural Community Assistance Corporation (RCAC) WELCOME! This training was funded as part of the EPA/RCAP Training/Technical Assistance to Improve Water Quality Project 1 Your Moderator Today… John Hamner Kelseyville CA [email protected] The Rural Community Assistance Partnership RCAC 4 2 RCAC Programs Affordable housing Community facilities Water and wastewater infrastructure financing (Loan Fund) Classroom and online training On-site technical assistance Median Household Income (MHI) surveys Time For a Quiz! 3 Your Presenter Today… Neil Worthen Las Cruces, NM [email protected] What “Micro-contaminants” Are We Talking About? Arsenic Disinfection By-Products (DBPs) Lead and Copper – As they relate to the distribution system 4 What’s In A Name?? Why just these four? Couldn’t all contaminants be considered micro-contaminants? How Did This Stuff Get In My Water? Erosion of natural deposits Human activity Chemical reactions during treatment and distribution Corrosion of pipes & fixtures 5 What Is Arsenic? A metalloid element, or chemical compounds containing arsenic Human Exposure Average 20 µg/day from food, air and water Arsenic is readily excreted from the body (3-5 day half life) The 20th most abundant element in the earths crust, and is the 12th most abundant element in the human body 6 Current Use Use is dropping because of toxicity 90% used as wood preservative (although this too is being phased out) Silicon based computer chips Feed additive (poultry and swine) Cotton fields Chemotherapeutic Arsenic In Drinking Water (Inorganic) Trivalent (As3+) – arsenic trioxide, sodium arsenite – arsenic trichloride Pentavalent (As5+) – arsenic pentoxide, arsenic acid, – arsenates (lead arsenate) 7 Chronic Toxicity Chronic exposure (drinking water) – Skin cancer (recognized >100 years ago) – Garlic odor on breath – Excessive perspiration – Muscle tenderness and weakness Chronic Toxicity Changes in skin pigmentation Paresthesia (numbing) in hands and feet Peripheral vascular disease Gangrene of feet – Blackfoot disease 8 Chronic Toxicity Drinking water at “low” levels of <100 µg/L (ppb) – Lung Cancer – Bladder Cancer – Skin lesions – Anemia – Nerve damage Susceptibility & Variability Children – small size, higher water consumption for size Genetic Age Nutrition 9 US Arsenic Map Safe Drinking Water Act USEPA - Drinking water MCL 10 µg/L (ppb) or 0.010 mg/L (ppm) If any water sample, past or present, has exceeded 10 ppb, a system may be out of compliance Additional information • US Environmental Protection Agency (EPA) – www.epa.gov 10 CCR Educational Statement “While your drinking water meets EPA’s standard for arsenic, it does contain low levels of arsenic. EPA’s standard balances the current understanding of arsenic’s possible health effects against the costs of removing arsenic from drinking water. EPA continues to research the health effects of low levels of arsenic which is a mineral known to cause cancer in humans at high concentrations and is linked to other health effects such as skin damage and circulatory problems.” CCR Health Effects Statement Some people who drink water containing arsenic in excess of the MCL over many years could experience skin damage or problems with their circulatory system, and may have an increased risk of getting cancer 11 Violation Determination Systems triggered into increased monitoring are not in violation until they have completed one year of quarterly sampling Any sample result that causes the RAA to exceed the MCL will be out of compliance immediately If a system does not collect all required samples, compliance will be based on the running annual average of the samples collected Monitoring If no water sample, past or present, has exceeded 0.010 ppm (10 ppb) As analysis every three years (State authorities may require more often) If a single water sample, exceeds 0.010 ppm (10 ppb) – Quarterly monitoring, beginning the next quarter after the results were received 12 Benefits Of Lower As Standard Reducing As from 50 µg/L to 10 µg/L will prevent: • 19-31 cases of bladder cancer (in US per year) • 5-8 deaths due to bladder cancer • 19-25 cases of lung cancer • 16-22 deaths due to lung cancer How Do I Get Rid Of This Stuff? Hmmmm...... Arsenic! Now what do I do?? 13 Mitigation Techniques Alternative source Blending Centralized treatment – Techniques • Side-stream treatment • Full treatment Existing technologies New technologies Point-of-use (POU) USEPA “Best Available Technology” (BAT) 14 Small System Compliance Technologies Waste Streams Liquid Residuals Solid Residuals – Brine – Spent resins – Backwash water – Spent media – Rinse water – Spent membranes – Concentrate – Sludges 15 Questions To Ask Will there be waste? Will it be Hazardous Waste? – Yes if listed as such or demonstrates hazardous characteristics How can you dispose of the waste? – Non-hazardous • Many options – Hazardous • Options more limited and expensive Questions For Your Engineer How many arsenic treatment plants have you designed/installed? How effective is the chosen treatment technology? How much are the capital costs? How much will the operations and maintenance costs be per gallon of water treated (including residual disposal costs)? Can you provide plant operation training? 16 Questions For Vendors Are there any arsenic treatment plants currently operating that use your technology? Can you demonstrate that your technology works with my water chemistry? Can you guarantee what the cost per gallon of water treated will be? Questions / Discussion 17 What Exactly Are Disinfection Byproducts (DBPs)? Chemical compounds created when chemical disinfectants combine with naturally occurring organic/inorganic “precursors” Can change day to day based on: – Season – Water temperature – Amount of disinfectant added – Quantity and types of organics What Exactly Are Disinfection Byproducts (DBPs)? (cont.) Total Trihalomethanes (TTHM) Haloacetic acids (HAA5) Bromate – Systems that use ozone Chlorite – Systems that use chlorine dioxide Dozens more that are unregulated 18 How Are DBPs Formed? Chlorine + organics = THM & HAA5 Ozone + Bromide = Bromate Chlorine + Triclosan = Chloroform Ultraviolet + organics = no DBPs DBP Health Effects Long-term exposure – Bladder cancer – Colon & rectal cancers Short term exposure at high levels – Reproductive and developmental health effects 38 19 Stage 1 DBPR Effective Dates: Surface water systems serving population more than 10,000 – January 1, 2002 Surface water systems serving population less than 10,000 and systems using groundwater not UISW – January 1, 2004 Stage 1 MCLs Total Trihalomethanes (TTHMs) Disinfection Maximum Detection Level for Byproduct Contaminant Level Reporting Total Trihalomethanes 0.080 mg/L 0.005 mg/L Bromoform 0.005 mg/L Chloroform 0.005 mg/L 0.080 mg/L Total Dibromochloromethane 0.005 mg/L Bromodichloromethane 0.005 mg/L 20 Stage 1 MCLs Haloacetic Acids (HAA5) Disinfection Maximum Detection Level for Byproduct Contaminant Level Reporting Total Haloacetic Acids 0.060 mg/L 0.005 mg/L Monochloroacetic Acid 0.005 mg/L Dichloroacetic Acid 0.005 mg/L Monobromoacetic Acid 0.060 mg/L Total 0.005 mg/L Dibromoacetic Acid 0.005 mg/L Trichloroacetic Acid Maximum Residual Disinfectant Level (MRDL) And Maximum Contaminant Levels (MCLs) MRDL Disinfectants MRDL (mg/L) Chlorine* 4.0 Chloramines* 4.0 Chlorine Dioxide 0.8 MCLs Disinfection Byproducts MCL (mg/L) Bromate* 0.010 Chlorite 1.0 TTHM 0.080 HAA5 0.060 * Based on running annual average 21 Who Must Comply With The DBP Rules? Community and Non-transient water systems Disinfects or delivers disinfected water Transient systems that use chlorine dioxide Does NOT apply to systems using only UV How Do I Get Rid Of This Stuff? Hmmmm...... DBPs! Now what do I do?? 22 DBP Chemistry - Precursors Natural Organic Matter (NOM) – Occurs in all surface water, decayed plant and animal matter Total Organic Carbon (TOC) – Includes NOM, pesticides, petroleum, etc Dissolved Organic Carbon – The largest fraction of TOC, and of the most concern THM Formation Factors .THM precursors (humic and fulvic acids) .Chlorine addition point .Chlorine concentration .Level and type of organics .pH of water in system: Higher pH = in THMs .Residence time (MRT) .Temperature 23 HAA5 Formation Factors .HAA5 precursors .Chlorine addition point .Chlorine concentration .pH of water in system: Low pH = in HAA5 .Temperature DBP Reduction Measures Remove precursors Modify treatment Change type or dose of disinfectants or oxidants Change points of application of disinfectants or oxidants Examine storage design, O & M Manage distribution system 24 Removing TOC Precursors New source Source water protection Treat algae blooms PAC or GAC Ion exchange Reverse osmosis Removing TOC Precursors Oxidize TOC with – Ozone, chlorine dioxide, chlorine – Hydrogen peroxide – UV light (photolysis) – Potassium permanganate – Other? 25 Modify Treatment Modify conventional treatment to optimize TOC removal Change contact basin geometry and/or baffling (adequate mixing) Provide adequate contact time to achieve disinfection Lower pH at chlorine application point (better disinfection/reduced dosage) 26 DBP Reduction Measures Changing type and dose of disinfectant – Examine points of application – know why are you adding that chemical at