Wastewater treatment Basics & Capacity.pptx

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1. Wastewater treatment basics

2. Does the facility generate industrial wastewater? Does your facility have Zero Liquid Discharge (ZLD)? Is the domestic/industrial wastewater treated onsite, offsite or both ? (if applicable) On-site wastewater treatment is the wastewater treatment plant used and managed by the factory only Off-site wastewater treatment is a third party enterprise or organization that provides wastewater treatment services (public or regional wastewater treatment facility) Is domestic wastewater sent into a septic system ? ( if applicable ) Wastewater

3. pH Similar to temperature, aquatic organisms cannot survive outside of specific pH ranges Image Source: http://www.ecy.wa.gov/programs/wq/tmdl/impairments/impairments.html

4. A characteristic of the water (not a pollutant) BOD is measurement of the amount of dissolved oxygen organisms require to breakdown organic wastes High BOD means microorganisms would likely deplete the dissolved oxygen breaking down the waste Essentially suffocating other organisms Biological Oxygen Demand (BOD)

5. Similar to BOD in that is a characteristic of water COD is measurement of ALL chemicals in the water that can be oxidized (not just those that microorganisms can ‘breakdown’) COD should always be higher than BOD Chemical Oxygen Demand (COD)

6. High Levels of Suspended Solids impact the ability to support a variety of aquatic life For example: Solids absorb heat from sunlight, which increases water temperature (which decreases levels of dissolved oxygen) Photosynthesis for also decreases, since less light penetrates the water Suspended solids can smother the eggs of fish and aquatic insects and directly clogs the gills of fish Suspended Solids

7. Too much nitrogen and phosphorus in water can cause Eutrophication which encourages algae to grow faster resulting in: Blocked sunlight Reduce dissolved oxygen Toxic algae blooms Excess nitrates in drinking water can harm infants Nutrients Image Source: World Resource Institute - http://www.wri.org/our-work/project/eutrophication-and-hypoxia

8. Heavy metals such as Cadmium, Lead, Mercury ,Hexavalent Chromium (Cr6) are toxic to both humans and aquatic life and can result in Nervous system and/or organ damage Cancers Heavy metal are also Bio accumulative and concentrate within the body and food chain i.e. mercury levels in Fish Heavy Metals

9. Wastewater Treatment Basics Wastewater treatment can take place on-site, off-site or a combination of both. Treatment processes and technology required depends on the type and concentration of pollutants in the wastewater. Physical, biological and chemical processes can be used in the treatment process and are commonly classified into three categories: Primary treatment Secondary treatment Tertiary treatment

10. Typically Physical/Chemical processes and supports the removal of organic/inorganic pollutants and metals, and can include: Screening Equalization Neutralization Sedimentation Coagulation Flocculation Primary Treatment

11. Physical removal of large solids (such as fibers, trash rags, sticks, grit and grease) Usually some type of screen or other separator (i.e. grease trap) Physical Screening

12. Combining of different flows and water composition into a tank to ‘equalize’ the characteristics May improves sedimentation efficiency The efficiency of a biological process can be increased (due to uniform flow characteristics and minimization of shock loads) Simplifies flow-rate-dependent operations (e.g. chemical feeding, sludge pumping) BOD reduction if aeration is used for mixing in the equalization basin. A point of return for recycling concentrated waste streams Equalization

13. Process of adjusting the pH of water through the addition of an acid or a base (i.e. HCl, NaOH) Many processes are pH dependent (e.g. coagulation) Increase efficiency of these processes pH adjustment for removal heavy metals Neutralization

14. Sedimentation or settling is the separation from water, by gravitational settling, of suspended particles that are heavier than water Sedimentation

15. Addition of flocculants or coagulants to form aggregates or flocs that can be settled out of the water i.e. Alum, Ferric sulphate, polymers Coagulation and Flocculation

16. Typically Biological (but may include chemical treatment) and supports the removal of organics and can include: Activated Sludge (aerobic digestion) Oxidation Secondary Treatment

17. Process in which wastewater flows through the aeration tank or “reactor” where aerobic bacterial culture is maintained in suspension. This process help to breakdown organic matter and remove nutrients (i.e. nitrogen/phosphorous) Activated Sludge (aerobic digestion)

18. Can be used to remove certain organic/inorganic pollutants, or to increase wastewater biodegradability Examples include: Fenton’s Reagent Solution of hydrogen peroxide and an iron catalyst that is used to oxidize contaminants (e.g. TCE) Alkaline Chlorination Used for removal of cyanide from plating operations Ozonation Treating of water with ozone to oxidize (i.e. break apart or destroy) compounds Oxidation

19. Can include any additional Chemical, Physical, Biological processes to further treat wastewater after primary and secondary treatment has occurred. Examples include: Reverse Osmosis Ultrafiltration Ion Exchange Thermal Evaporation Carbon Filtration Tertiary Treatment Ultrafiltration Reverse Osmosis

20. Zero-liquid discharge (ZLD) is an advanced water treatment process in which all wastewater is purified and recycled leaving no liquid discharge of wastewater at the processes. ZLD includes processes such as ultrafiltration, reverse osmosis, evaporation/crystallization and distillation. ZLD systems still produce solid sludge that requires appropriate solid waste management procedures for safe disposal Advanced Treatment - Zero Liquid Discharge

21. How to understand capacity: Basics 1 Understanding the water balance 2 Inlet and outlet data 3 Per hour capacity, working days, per day wastewater treated/generated

22. ZDHC Wastewater guideline

23. MRSL Group CAS analytes Alkylphenol (AP) and Alkylphenol Ethoxylates (APEOs) 17 Chlorophenols 19 Dyes – Azo 24 Dyes – Navy Blue Colourant 1 Dyes – Carcinogenic or equivalent concern 15 Dyes – Disperse ( sensitising ) 19 Short-chain Chlorinated Paraffins (SCCPs) 1 Flame Retardants 31 Glycols 8 Halogenated Solvents 5 Organotin Compounds Number not specified ZDHC MRSL