Developing a Wastewater Treatment Training Program for the Mexican Metal Plating Industry Located at the Arizona-Mexico border Kiril Hristovski, Ph. D, The Polytechnic School at Arizona State University Al Brown, MPA, The Polytechnic School at Arizona State University Frank C. Brown, The Polytechnic School at Arizona State University
Sponsored and Supported by: Border Environment Cooperation Commission International Boundary and Water Commission Environmental Protection Agency Secretariat of Environment and Natural Resources Arizona Department of Environmental Quality Nogales, Sonora Potable Water and Wastewater Utility 2
Santa Cruz Watershed 3
Introduction Santa Cruz river is major source of water for: Nogales (AZ and Sonora) Santa Cruz County Water uses: Irrigation waters Increases water levels for local municipalities Supports local riparian areas 4
Recent Issues AzPDES pollutants of concern (POC) permit maximums exceeded downstream of Nogales International Water Treatment Plant (NIWTP) Attributed to exceedance of Allowable Headworks Loading limits (AHLs) the NIWTP plant was designed to handle. ADEQ has established a Maximum Allowable Headworks Loading rate (MHAL) for each POC at a lower level to serve as an early warning 5
Contaminants of Concern Pollutant AHL sol (kg/day) MAHL saf (kg/day) Exceedance First Impacts Cadmium 0.25 0.19 Biosolids Chromium 1.02 0.77 Biosolids Nickel 8.36 6.27 Biosolids Copper 41.82 5.73 Effluent Zinc 79.40 12.1 Treatment Process Lead 1.37 0.67 Effluent Cyanide ---- 2.28 Effluent 6
Daily Loading at NIWTP Border Station Cadmium Chromium 1.2 3 1 2.5 0.8 2 Kilograms per day 0.6 0.4 Kilograms per day 1.5 1 0.2 0.5 0 0 2nd Quarter 2014 2nd Quarter 2014 Actual Loading Allowable Loading Actual Loading Allowable Loading 7
Daily Loading at NIWTP Border Station Copper Lead 20 1.4 18 1.2 16 14 1 Kilograms per day 12 10 8 Kilograms per day 0.8 0.6 6 0.4 4 2 0.2 0 0 2nd Quarter 2014 2nd Quarter 2014 Actual Loading Allowable Loading Actual Loading Allowable Loading 8
Daily Loading at NIWTP Border Station Nickel Zinc 40 25 35 30 20 Kilograms per day 25 20 15 Kilograms per day 15 10 10 5 5 0 0 2nd Quarter 2014 2nd Quarter 2014 Actual Loading Allowable Loading Actual Loading Allowable Loading 9
Concerns at the Headworks Poor treatment practices lead to: Hindrance of Nogales International Wastewater Treatment Plant (NIWTP) treatment train Increased loading rates for Pollutants of Concern (POC) Failure to meet AzPDES permit standards Adversely affect riparian areas post discharge Disposal cost increase for bio solids Reduce or eliminate ability to land apply bio solids 10
OUR MISSION: Through education and training the Border 2020 project seeks to: Reduce the release of POC from metal plating wastewater stream Decrease POC loading at the NIWTP headworks Reduce operating costs for both the metal plating facilities and the NIWTP Integrate Arizona s and Mexico s wastewater management and monitoring systems. 11
CURRICULUM 12
Target Audience 135 permitted sites that use discharge to the POTW. 64 flagged based on materials, equipment, processes used. 5 plating facilities 13
Wastewater Treatment Process Wastewater Treatment Plant Define what it is Plant or facility designed to treat water by a combination of treatment methods (chemical, physical, or biological) to a level that allows it to be used for other purposes. Identify processes Pre, primary, secondary, and tertiary treatment processes Identify sources of water Municipal, agricultural, industrial, etc. 14
Typical Wastewater Treatment Train Bar Screen Grit Removal Primary Clarifier Influent Sludge Thickening Secondary Clarifier WAS Activated Sludge Dewatering RAS Aerobic Digestion Filtration Disinfection Effluent
Nogales International Wastewater Treatment Train Influent Screen/Grit Removal Modified Ludzack-Ettinger Treatment Sludge Thickening Filter Press Activated Sludge Clarifier WAS RAS Filtration Disinfection Effluent Aerobic Digestion Disposal/Reuse
Biosolids Define Nutrient-rich organic materials obtained from wastewater treatment and used beneficially, as for fertilizer. Issues How exceedance of AHLs affects biosolids Limits application Increases disposal costs Standards US EPA/ADEQ MEX NOM-004-SEMARNAT-2002 17
Biosolids Land Application Requirements US EPA REQUIREMENTS 4 General Requirements for Land Application 1. Meet Ceiling Concentration Limits. 2. Meet either Pollution Concentration Limits, Cumulative Pollutant Loading Rate limits, or Annual Pollutant Loading Rate limits. 3. Meet either Class A or B Pathogen Requirements. 4. Meet 1 of 10 Vector Attraction Reduction Requirements.
Biosolids Land Application Requirements MEXICO NOM-004-SEMARNAT-2002 REQUIREMENTS 2 General Requirements for Land Application 1. Meet Permissible Heavy Metal Contaminant Limits. Excellent or Good rating depending on the use 2. Meet either Class A or B Pathogen and Parasite Limits. Class A, B, or C rating depending on the use
Pollutant (Determined in Full) Biosolids Heavy Metals Maximum Permissible Limits Excellent (mg/kg on dry basis) Good (mg/kg on dry basis) Arsenic 41 75 Cadmium 39 85 Chromium 1200 3000 Copper 1500 4300 Lead 300 840 Mercury 17 57 Nickel 420 420 Zinc 2800 7500
Class Bacteriological Indicator of Pollution Fecal Coliform MPN/gm on dry basis Biosolids Pathogen and Parasite Maximum Permissible Limits Pathogens Salmonella sp. MPN/g on dry basis Parasites Helminth eggs/g on dry basis A < 1000 < 3 < 1 (viable eggs) B < 1000 < 3 < 10 C < 2 10 6 < 300 < 35
Biosolids Applicability Type Class Use(s) Excellent A Urban uses with direct public contact during application Excellent or Okay B Urban uses without direct public contact during application Excellent or Okay C Forest uses Soil improvement Agricultural uses
CURRENT PRACTICES FOR INDUSTRIAL WASTEWATER TREATMENT 5/4/2015 23
Treatment Processes Redox reactions What they are Define the parts Identify POC process used on (i.e. hexavalent chromium and cyanide) Chemical Precipitation, Coagulation-Flocculation Define Break down components that effect process K sp ph Ion-exchange Define and briefly touch on process 24
Redox Reactions The process of Oxidation is when an atom, ion, or molecule becomes more positively charged, i.e. when it loses electrons. The process of Reduction is when an atom, ion, or molecule becomes more negatively charged, i.e. when it gains electrons. Oxidation and Reduction reactions do not occur separately, so if something is losing electrons them something else is gaining them OXIDIZED REDUCED e- e- A B A B
Redox Reactions Cr(VI) Reduction Step 1 Sulfuric Acid is added to drop ph below 2.0 H 2 SO 4 Step 2 Sodium Metabisulfite forms Sodium Bisulfite when added to water Na 2 S 2 O 5 + H 2 O 2NaHSO 3 Step 3 Sodium Bisulfite is used to reduce Cr(VI) to Cr(III) 2H 2 CrO 4 + 2NaHSO 3 + 3H 2 SO 4 Cr 2 (SO 4 ) 3 + 3NaHSO 4 + 5H 2 O Step 4 Can now be added back into waste stream for precipitation
Redox Reactions Cr (III)Precipitation Step 1 Caustic Soda is added (also helps to raise ph) NaOH Step 2 Cr(III) is precipitated out 6NaOH + Cr 2 (SO 4 ) 3 2Cr(OH) 3 +3Na 2 SO 4
Cr(VI) Reduction/Precipitation Dilute Sulfuric Acid Dilute Caustic Soda Polymer SO 2 Influent Effluent 15 to 30 min ph 2. 0 ORP +250 mv 10 to 20 min ph 8. 0 to 8. 5 Sludge Processing Reduction Precipitation Settling
Solubility Product Constant K sp - Solubility Product Constant K sp is a constant value that tells you the amount of solute (contaminant) that will dissolve in a solvent (water). The larger the K sp the harder it is to precipitate out the contaminant. The smaller the K sp the easier it is to precipitate out the contaminant. K sp is helpful in determining how contaminants will react in the presence of each other and optimal precipitation ph.
Solubility vs ph of Metal Hydroxides and Metal Sulfides 30
Sampling IMPORTANCE OF SAMPLING AND ANALYSIS
Sampling and Analysis What is sampling? Types of samples Sampling method Sampling tools Sampling plan Why is it important? How do you sample? Basic sampling methods Liquids and solids Tagging/labeling samples Log book Transport COC Storage Picture courtesy of response.restoration.noaa.gov 32
Overview of the Most Significant Hazards WORKER HEALTH AND SAFETY AT METAL PLATING FACILITIES
Worker Health and Safety States of Matter Foundation to understanding hazards Types of Hazards and Prevention Biological, Chemical, and Physical TRIC Routes of exposure Health effects Fire triangle PPE Safe practices 34
Current and Future Efforts Current focuses: Decreasing Loading rates of POC Decreasing concentrations of POC in bio solids Reducing operational costs In the future: Reducing effluent and biosolid concentrations Provide capacity for daily on-site chemical analysis of wastewater 35
Questions/Discussion Contact info for Al Brown: al.brown@asu.edu 480-727-1320 July 22, 2012 Footer text here 36