Water Quality Management PDF - Env.E. 101 Fall 2024

Water Quality and it’s Management Env.E. 101 Fall 2024 Water Facts Water covers 70% of the Earth’s surface in many different forms. Surface waters include oceans and seas that carry 97% of the total water as reservoirs of saltwater and inland waters in the form...

Water Quality and it’s Management Env.E. 101 Fall 2024 Water Facts Water covers 70% of the Earth’s surface in many different forms. Surface waters include oceans and seas that carry 97% of the total water as reservoirs of saltwater and inland waters in the form of rivers and lakes. 2 Distribution of Earth’s Water  Freshwater Availability unevenly distributed! 20% of the global population lacking access to safe drinking water http://www.unep.org/dewa/vitalwater/ Main Uses of Freshwater Resources Main Uses of Freshwater Resources 1.Domestic 2.Industrial 3.Agricultural Domestic Water Use People in developed countries on average consume about 10 times more water daily than those in developing countries. – The average person use in developed countries : 500-800 L/day (300 m3 /year), compared to 60- 150 L/day (20 m3/year) in developing countries http://www.unep.org/dewa/vitalwater/article48.html Industrial Sector In the industrial sector, the biggest share of freshwater is stored in reservoirs and dams for electrical power generation. Industrial uses account for about 20% of global freshwater withdrawals. Of this, – 57-69% is used for hydropower and nuclear power generation – 30-40% for industrial processes – 0.5-3% for thermal power generation Agricultural sector Agriculture accounts for 67% of the world’s total freshwater withdrawal, and 86% of its consumption. By 2025, agriculture is expected to increase its water requirements by 1.3 times, industry by 1.5 times, and domestic consumption by 1.8 times. http://www.unep.org/dewa/vitalwater/article48.html Water as a Resource Humans depend on very small reservoirs of water for all our needs These reservoirs cycle/ turnover very quickly Hydrologic Cycle  Water Reservoirs As water reservoirs cycle they collect pollution from various sources, be cleaned by passing through functioning ecosystems 12 Water Pollution the contamination of water bodies, usually as a result of human activities. any chemical, physical or biological change in the quality of water that has a harmful effect on any living thing that drinks or uses or lives in it 13  Sources of pollutants 1. Point sources 2. Non-point sources 14 Point and Non-point Sources  Point Sources Direct discharges to a single point Examples: – Domestic sources (sewage or domestic wastewater) – Industrial sources (industrial wastewater) 16  Point Sources Direct discharges to a single point Examples: – Domestic sources (sewage or domestic wastewater)  Combined system  Separate system bypass Sewage + WW Treatment Plant storm water 17 Non-point Sources  Agricultural sources Excess fertilizers, herbicides, and insecticides from agricultural lands and residential areas Bacteria and nutrients (N, P) from livestock, pet wastes, urban runoff Sediment from improperly managed crop and forest lands, and eroding streambanks Atmospheric deposition 18  Point vs non-point source pollution Point Sources Non-point Sources Easy to control Difficult to control Collected and conveyed to a Requires good soil treatment facility which can conservation and agri- easily be monitored by practices (e.g. controlled regulatory authorities. application of pesticides and fertilizers) 19 Domestic Wastewater Organics Nutrients (N, P, S, etc.) Suspended solids Pathogens Inorganic chemicals (acids, salts, heavy metals) 20 Industrial Wastewater Composition will vary depending on the industry Complex organics Inorganic chemicals (heavy metals of Hg, Cr, Ni, Cu, Pb…) Heat Other 21 Agricultural Wastewater Fertilizers and pesticides Nutrients (N, P, S, etc.) Sediments and suspended solids Acid mine drainage from mining activities… 22 Water Pollutants Pathogens Oxygen-demanding substances Nutrients Suspended solids Inorganic chemicals (acids, salts, heavy metals) Hazardous organics (oil, EDCs, PPCPs, microplastics, pesticides) 23 Pathogens Pathogens are disease-causing bacteria, viruses and protozoa, usually from human sewage cause water-related diseases (e.g. gastro- intestinal, typhoid, shigellosis, hepatitis and cholera) often contamination through contact with water or via food (e.g. via irrigated agriculture, or via fish/shellfish) 24 Oxygen-demanding substances Organic substances (mainly) Orginate from – Municipal discharges – Industrial wastewaters – Agriculture Cause the exhaustion of oxygen in water resources and the development of septic conditions, fish kills Measured as BOD, COD or TOC 25 Nutrients N and P Under normal conditions, nutrients are beneficial and necessary, but in high concentrations, they can become an environmental threat. 26 Nutrients They cause; – The growth of undesirable aquatic life (massive algal blooms, the decay of which can create odors and rob the waters of life-sustaining dissolved oxygen) – Groundwater pollution (e.g. NO3) 27 Where do N emissions originate? – fertilizers – animal wastes – failing septic tanks – uncontrolled sewage discharges – uncontrolled industrial waste streams 28 Nitrogen Nitrogen can exist in several forms (organic or inorganic). Organic nitrogen (e.g. proteins) exerts an oxygen demand. Inorganic nitrogen forms (e.g. NH3, NO3) support the growth of aquatic plants and algae. N forms are soluble, easily leaches from soil. 29 Phosphorus Major sources; – Fertilizers – Urban wastewater (automobile exhaust and car washing, phosphorus-based soaps, detergents, and chemicals) – Industrial wastewater (food processing plant effluents) – The weathering of rock 30 Phosphorus – Phosphorus can exist in several forms (organic or inorganic). – Limiting nutrient – When an excessive amount of phosphorus is introduced, some plant species, such as algae, experience explosive growth – Associated with sediments; can be re-suspended or released from sediments 31  Suspended solids Organic or inorganic (mostly) particles From improperly managed construction sites, crop and forest lands, eroding streambanks and industrial discharges Nutrients often become attached to sediments , and sediments are easily transported by stormwater Cause; – an increase the turbidity of the water, reducing the available light for light depending organisms – suspended solids deposition that cover benthic species – prevailing of anaerobic conditions 32 Hazardous organics EDCs*, pesticides*, PPCPs, microplastics Toxic to aquatic life with mutagenic properties can cause carcinogenic and mutagenic effects. *Please recall from previous lecture notes 33 Pharmaceuticals and Personal Care Products (PPCPs) A class of compounds that are applied externally or ingested by humans, pets, and other domestic animals Released to the environment through – the disposal of expired unwanted, or excess medications and care products to the sewage system Deodorants, sunscreens, etc 34 Microplastics Microplastics are small plastic pieces less than five millimeters long which can be harmful to our ocean and aquatic life. Inorganic chemicals Acids, salts, heavy metals... Large quantities of these compounds will make water unfit to drink and will cause the death of aquatic life 36 Heavy metals Hg, Cu, Cr, Ni etc. Sources: industrial discharges, dump sites, urban runoff, acid drainage from abandoned mines Toxic to aquatic life Some heavy metals can concentrate in shellfish and fish tissues and damage the physiological processes and functions and resulting in unacceptable high concentrations for consumers (Please recall bioaccumulation/biomagnification from Lecture notes 2). 37 Water Quality Management Control of pollution from human activity so as to ensure that the water is suitable for its intented use such as, – Drinking water, – Industrial use, – Irrigation, – Wildlife – Recreational activity, etc. 38 Water Quality Management Also; The science of knowing: - how much of waste is too much for a particular water body or - how much of waste can be assimilated by the water body 39 Water Quality Standards are the measures that specify the concentrations of substances permissible for all intended water uses at a specific location on a lake, river or sea. Define the water quality goals for a waterbody Provide a regulatory basis for many actions e.g. Drinking water standards, irrigation water standards etc. Water Quality Standards – e.g.