Waste_Water_Treatment.pptx engineering environment

Waste_Water_Treatment.pptx engineering environment

1. Waste Water Treatment

2. Waste Water Treatment Usually refer to sewage treatment, or domestic wastewater treatment process of removing contaminants from wastewater, both runoff and domestic Residences (kitchen, bathroom) Commercial institution Industrial institution (usually require specialized treatment process) SOURCE OF WASTE WATER

3. Purpose: To manage water discharged from homes, businesses , industries & to reduce the threat of water pollution. To produce waste stream (effluent) To produce solid waste (sludge) To discharge or reuse them back into the environment

4. How can it be treated? Collected and transported via a network of pipes and pump stations to a municipal treatment plant

5. Stages of water treatment Primary solids are separated Secondary dissolved biological matter is converted into a solid mass by using water-borne bacteria 95% of the suspended molecules should be removed Tertiary biological solids are neutralized then disposed, and treated water may be disinfected chemically or physically

6. Types of Treatment Mechanical treatment Influx (Influent) Removal of large objects Removal of sand and grit Primary Sedimentation Biological treatment Trickling bed filter Activated sludge Chemical treatment Disinfection

7. Preliminary Treatment - removes large objects and non-degradable materials - protects pumps and equipment from damage - bar screen and grit chamber Bar Screen - catches large objects that have gotten into sewer system such as bricks, bottles, pieces of wood, etc Grit Chamber removes rocks, gravel, broken glass, etc. Mesh Screen - removes diapers, combs, towels, plastic bags, syringes, etc.

8. Treatment stages - Primary Treatment typical materials that are removed during primary treatment include fats, oils, and greases (eg. FOG) sand, gravels and rocks (eg. grit) larger settleable solids including human waste, and floating materials

9. Primary treatment reduces the suspended solids and the B.O.D. of the wastewater. From the primary treatment tanks water is pumped to the trickling filter for secondary treatment. Secondary treatment will further reduce the suspended solids and B.O.D. of the wastewater. Wastewater Treatment

10. Treatment stages - Secondary Treatment or Biological Treatment Degrade biological content (dissolved organic matter) of the sewage Ex: human waste, food waste, soaps, detergent Added bacteria and protozoa into sewage.3 different approaches Fixed film system Suspended film system Lagoon system

11. Three approaches Fixed Film Systems grow microorganisms on substrates such as rocks, sand or plastic wastewater is spread over the substrate Ex: Trickling filters, rotating biological contactors Spread wastewater over microorganism made of coke (carbonised coal), limestone chips or specially fabricated plastic media Optimize their thickness by insect or worm grazing Trickling filters bed

12. Suspended Film Systems stir and suspend microorganisms in wastewater settled out as a sludge pumped back into the incoming wastewater Ex: Activated sludge, extended aeration Secondary Treatment or Biological Treatment & Role of Microorganisms Activated sludge Mixed community of microorganisms .Both aerobic and anaerobic bacteria may exist. Biological floc is formed

13. 5 physical components of Activated Sludge process Aeration tank oxygen is introduced into the system

14. Aeration source ensure that adequate oxygen is fed into the tank provided pure oxygen or compressed air

15. Secondary clarifiers activated-sludge solids separate from the surrounding wastewater

16. Activated sludge outflow line Pump activated sludge back to the aeration tank Effluent outflow line discharged effluent into bay or tertiary treatment plant Activated sludge

17. Lagoon Systems hold the waste-water for several months natural degradation of sewage Usually reeds are preferred

18. a Methanogenic Bacteria : These bacteria, also refered to as methanogens Or methane formers are responsible for the conversion of acetic acid and Hydrogen to methane and carbondioxide.The most important methanogens belong to the genera Methanobacterium, Methanobacillus, Methanococcus Role of Microorganisms…. A consortium of anaerobic microorganisms work together for degradation Of sludge(or sewage) organic matter. They may be categorized into two types Acid-Forming bacteria : Also known as acidogens or non-methanogenic Bacteria. They bring out the hydrolysis of macromolecules (e.g.carbohydrate) to simple substrates (e.g.monosaccharides), and the latter to acids e.g. Clostridium sp, Lactobacillus sp, E.coli

19. Tertiary Treatment Remove disease-causing organisms from wastewater There are four major processes under the Tertiary Treatment Solids removal Biological nitrogen removal Biological phosphorus removal Disinfection There are 3 different disinfection process Chlorination UV light radiation Ozonation

20. BIOLOGICAL NITROGEN REMOVAL NITRIFICATION: Ammonia(NH4+) Nitrosomonas Nitrite Nitrobacter Nitrate DENITRIFICATION: Nitrate(NO3-) Nitrite Nitric oxide Nitrous oxide Nitrogen gas

21. Biological Phosphorous Removal The phosphorus enriched supernatant that comes out of the phosphorus Stripper is treated with lime to precipitate the phosphorus .The resultant Liquid supernatant can be returned to the aeration tank for further treatment.

22. Chlorination Most common Advantages: low cost & effective Disadvantages: chlorine residue could be harmful to environment

23. UV light radiation Damage the genetic structure of bacteria, viruses and other pathogens. Advantages: no chemicals are used water taste more natural Disadvantages: high maintenance of the UV-lamp

24. Ozonation Oxidized most pathogenic microorganisms Advantages: safer than chlorination fewer disinfection by-product Disadvantage: high cost

25. Waste Water Treatment of some Industries (Dairy) Dairy facilities Shed facilities (washing of herd, Milking, manure) Anaerobic pond treatment Aerobic Pond treatment Treated water

26. Waste Water Treatment of some Industries (Distillery) Organic matter Bacterial oxidation Acids, Alcohols, Aldehydes,ketones New Bacterial cells Bacterial Oxidation CO2,CH4, NH3,H2S etc

27. Waste Water Treatment of some Industries (Tannery) Biological Acidification Anaerobic sludge Blanket reactor Processing of sulfide sulfur SLUDGE SLUDGE NaHS

28. Summary

29. Disposal of wastewaters from an industrial plant is a difficult and costly problem. Most petroleum refineries, chemical and Nuclear plants ,Dairy and Tannery plants have onsite facilities to treat their wastewaters so that the pollutant concentrations in the treated wastewater comply with the local and/or national regulations regarding disposal of wastewaters into community treatment plants or into rivers, lakes or oceans. Constructed wetlands are being used in an increasing number of cases as they provided high quality and productive on-site treatment. Other Industrial processes that produce a lot of waste-waters such as paper and pulp production has created environmental concern leading to development of processes to recycle water use within plants before they have to be cleaned and disposed of. Treated wastewater can be reused as drinking water, in industry (cooling towers), in artificial recharge of aquifers, in agriculture and in the rehabilitation of natural ecosystems. Conclusion