EAT 131: ENVIRONMENTAL CHEMISTRY

1. EAT 131: ENVIRONMENTAL CHEMISTRY CHAPTER 3: WATER QUALITY PARAMETERS

2. Water Quality Parameters • Turbidity • Colour • pH • Alkalinity • Hardness • Chloride • Solid • COD • BOD • Nitrogen • Fluoride

3. Introduction • Water is a resource that has many uses, including recreational, transportation, hydroelectric power, agricultural, domestic and industrial uses. • In Malaysia, 42 of 50 major rivers are reported to be "ecological disasters”. Residues from palm oil and rubber manufacturing, along with heavy erosion from logging of tropical rain forests, have destroyed all higher forms of life in most of these rivers.

4. Water pollution • is the contamination of water bodies (e.g. lakes, rivers, oceans, groundwater). • Water pollution can be defined as any physical, biological, or chemical change in water quality that adversely affects living organisms or makes water unsuitable for desired uses. • Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds.

5. Water quality is the physical, chemical and biological characteristics of water. • Physical characteristic: solid, temperature, turbidity, color, odor, conductivity etc • Chemical characteristic: nitrogen, phosphorus, alkalinity, sulphate, chloride, metals, BOD, COD, TOC etc • Biological characteristic: coliform organisms, toxicity

6. Source of water pollution

9. Sources of surface water pollution • Point source pollution - refers to contaminants that enter a waterway through a discrete conveyance, such as a pipe. 

10. Non-point source pollution - refers to diffuse contamination that does not originate from a single discrete source. NPS pollution is often the cumulative effect of small amounts of contaminants gathered from a large area.

11. The specific contaminants leading to pollution in water include a wide spectrum of chemicals, pathogens, and physical. Pathogens: • Coliform bacteria, Burkholderia pseudomallei; Cryptosporidium parvum; Giardia lamblia; Salmonella; Novovirus and other viruses. • High levels of pathogens may result from inadequately treated sewage discharges. • Chemical contaminants: • Organic water pollutants • Inorganic water pollutants

12. Measurement of water pollution • Water pollution may be analyzed through several broad categories of methods: physical, chemical and biological. Most involve collection of samples, followed by specialized analytical tests. Some methods may be conducted in situ. • Physical testing: • solids concentration like total suspended solids (TSS) and turbidity • Biological testing: • Biological testing involves the use of plant, animal, and/or microbial indicators to monitor the health of an aquatic ecosystem; Coliform bacteria are a commonly used bacterial indicator of water pollution

13. Chemical testing: • Water samples may be examined using the principles of analytical chemistry. Many published test methods are available for both organic and inorganic compounds. • Frequently used methods include pH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), nutrients (nitrate and phosphorus compounds), metals (including copper, zinc, cadmium, lead and mercury), oil and grease, total petroleum hydrocarbons (TPH), and pesticides.

14. Water Treatment

15. Drinking Water:

18. Industrial wastewater: • The different types of contamination of wastewater require a variety of strategies to remove the contamination • Solids removal Multi media filtration Sedimentation tank Ultrafiltration

19. Coagulation and flocculation processes may be used, using alum salts [KAl(SO4)2.12H2O] or the addition of polyelectrolytes.

20. Heavy metal removal: • Trace metal removal including arsenic, lead, copper, zinc, cadmium, chromium, nickel, iron and manganese removal. • Chemical Precipitation:  • By controlling the pH and by adding precipitation reagents (sulphurs, carbonates, phosphates), coagulation-flocculation agents (iron chloride, aluminum hydroxide).

22. Ion exchanger: • Cation exchanger resin - is an insoluble matrix normally in the form of small (1–2 mm diameter) beads, usually white or yellowish, fabricated from an organic polymer substrate.

25. Removal of biodegradable organics: • Biodegradable organic material is usually possible to treat using extended conventional wastewater treatment processes such as activated sludge or trickling filter. • Problems can arise if the wastewater is excessively diluted with washing water or is highly concentrated. • The presence of cleaning agents, disinfectants, pesticides, or antibiotics can have detrimental impacts on treatment processes.

26. Activated sludge process • Activated sludge is a biochemical process for treating sewage and industrial wastewater that uses air (or oxygen) and microorganisms to biologically oxidize organic pollutants, producing a waste sludge (or floc) containing the oxidized material. In general, an activated sludge process includes: 1) An aeration tank where air (or oxygen) is injected and thoroughly mixed into the wastewater. 2) A settling tank (usually referred to as a "clarifier" or "settler") to allow the waste sludge to settle

28. Trickling filter process: • Trickling filter consists of a bed of rocks, gravel, or plastic media over which wastewater flows downward and contacts a layer (or film) of microbial slime covering the bed media.