Lecture 5. - Water Quality and IWRM - Soil and groundwater pollution and control Environmental Engineering Management (EEM 690) FAISAL ANWAR
Water Quality Management: Rules and Regulations Drinking Water: Australian Drinking Water Quality Guideline or WHO guideline Water Pollution Control in Australia: ANZECC Guidelines for Fresh and Marine Waters (Australian and New Zealand Environment Conservation Council) NHMRC recreational waters guidelines Around the world however is taking the USEPA’s and WHO’s guideline as the basis to enact their own guideline.
Water Resources Management System Water Supply Subsystem Wastewater Disposal Subsystem River basin management system Groundwater and aquifer management system Urban stormwater management
Water Supply Subsystem Components Raw water source – Treatment – Distribution – Customer Objective Provide ample supply of water that meets the requirement of end uses of customers
After using the water We dispose it to the sewer or other places depending on the disposal methods. Wastewater system starts from the users (customers)
Wastewater disposal subsystem Components Customer – Wastewater Collection – Wastewater Treatment – Disposal Objective Safely collect and dispose so that health and aesthetics of public or any other beneficial uses of water is not affected.
Industry Wastewater Treatment Plant Deep water Ocean Outfall Wastewater collection and disposal system
Sources of WW Characteristics are different for different origins of wastewater Residence - kitchen sink, toilet, shower, bath, washing machine, storm water from roof Commercial establishments Hospitals Industry Agriculture Animal farming Aquaculture
Disposal sites Depending on where it is disposed it has to be treated differently Disposal sites: usually water bodies like river, lake, ocean and land fills
Oxygen Demanding Material • Anything that can be oxidized in the receiving water with the consumption of dissolved molecular oxygen is termed oxygen-demanding material. This material is usually biodegradable organic matter but also includes certain inorganic compounds. The consumption of dissolved oxygen (DO) poses a threat to fish and other aquatic species.
Nutrients • Nitrogen and Phosphorous, two nutrients of primary concern, are considered pollutants. All living things require these nutrients to grow but problems arises when it is in excess amount.
Pathogenic organisms • Microorganisms found in wastewater include bacteria, viruses, and protozoa excreted by diseased persons or animals. When discharged into surface waters, they make the water polluted (non-drinkable). If the pathogen concentration is high enough, the water may be unsafe for swimming and fishing.
Suspended solid • Organic and inorganic particles that are carried by the wastewater into a receiving water are termed as Suspended solid (SS) • SS usually settle in the bottom when the flow velocity in reduced such as in Lake or pool. • Colloidal particles that do not settle causes turbidity in the surface water bodies.
Salts • Salt present in water are normally measured by evaporation of a filtered water sample. The salts and other things that do not evaporate are called as total dissolved solid (TDS). Problem arises when TDS is such that it is no longer usable for drinking and irrigation. High concentration of TDS are discharged by many industries and urban storm runoff.
Toxic Metals and Toxic organic compounds • Agricultural runoff often contains pesticides and herbicides. Urban runoff is a source of zinc in many water bodies. Other toxic metals and organic compounds are discharged by many industries.
Endocrine-Disrupting Chemicals (EDCs) • EDCs, a class of chemicals, can alter the normal physiological function of endocrine system and can affect the synthesis of hormones. They can interfere with the regulation of reproductive and developmental process in mammals, birds, reptiles and fish.
Water Quality Management in Rivers • The objective of water quality management is to control the discharge of pollutants so that water quality is not degraded to an unacceptable extent below the natural background level. • We must be able to measure the pollutants, predict the impact of the pollutant on water quality, determine the background water quality (i.e without human intervention), and decide the levels acceptable for intended uses of the water.
Water Quality Management in Rivers • The impact of pollution on a river depends on: - nature of the pollutant - characteristics of the individual river (i.e. open channel) – discharge capacity and flow velocity. Water depth, bottom slope and sediment materials and surrounding vegetation. - Climate of the region - mineral heritage of the watershed - land use pattern - types of aquatic life in the river • All of these factors should be considered for case by case. Some pollutants such as sediments, salt and heat may by highly susceptible to some rivers, while some other may tolerate them without much damage
Total Maximum Daily Load (TDML) • TDML specifies the maximum amount of pollutant that a water body can receive and still meet water quality standards. • TMDL allocates pollutant loadings that may be contributed among point and non-point sources. • TMDL is computed by: TMDL=WLA + LA + MOS WLA = waste load allocations, that is, portions of the TMDL assigned to existing and future point sources. LA = load allocations, that is, portions of the TMDL assigned to existing and future non-point sources. MOS = margin of safety which is to account for uncertainty about relationships between loads and water quality. • A software system called Better Assessment Science Integrating Point and non-Point Sources (BASINS) that integrates a GIS, national watershed and meteorological data, and state-of-the-art environmental assessment and modeling tools is used to develop the TMDL (Ahmed 2002; US EPA 2005).
Effect of Oxygen-Demanding Wastes on Rivers • The introduction of oxygen demanding materials (organic or inorganic) into a river causes the depletion of DO in water. • This poses threat to fish and aquatic life if DO concentration falls below a critical point. • To predict the extent of oxygen depletion, it is necessary to know how much waste is being discharged and how much oxygen is required to degrade the waste.
Chemical Oxygen Demand (COD) • Chemical Oxygen Demand (COD): is a measured quantity that does not depend on knowledge of the chemical compositions of the substances in water. • A strong chemical oxidizing agent is (chromic acid) mixed with a water sample and then boiled. The difference between the amount of oxidizing agent at the beginning of the test and that remaining at the end of the test is used to calculate the COD.
Biochemical Oxygen Demand (BOD) • If the oxidation of an organic compound is carried out by microorganisms using the organic matter as a food source, the oxygen consumed is known as BOD. • The BOD test is an indirect measurement of organic matter because we actually measure only the change in DO concentration caused by the microorganisms as they degrade the organic matter.
DO Sag • The concentration of DO in a river is an indicator of the general health of the river. • All rivers have some capacity of self-purification. As long as the discharge of the oxygen-demanding wastes is well within the self-purification capacity, DO level will remain high to maintain the good quality of aquatic environment. • As the amount wastes increase and DO level falls where aquatic environment is highly disturbed. After some time it’s DO level again increase with aeration from atmosphere. • If DO=0, all the fish and other animals are killed and water becomes blackish and foul smelling as the sewage and dead animal life decompose under anaerobic conditions.
Effect on Nutrients on Water Quality in Rivers • Effects of Nitrogen: - In high concentration, NH3-N is toxic to fish - NH3 in low concentration, and NO3- serve as nutrients for excessive growth of algae - The conversion of NH4+ to NO3- consumes large quantities of DO • Effect of Phosphorus: P enhance the growth of algae. When the algae die, it becomes the oxygen-demanding material as bacteria seek to degrade them. As a result DO level decreases. Management Strategy: Controlling the nutrient-caused water quality problems in streams is based on the removal of N or P from wastewater before it is discharged.
Water Quality in lakes and Reservoir
Thermal Stratification is driven by the relationship between temperature and density
Nutrient and Trophic State • Trophy is defined as the rate at which organic matter is supplied to lakes, both from the watershed and through internal production. • The growth of algae and macrophytes in lakes is influenced by conditions of light and temperature and the supply of nutrients. • As temperature and light is more or less constant in a region, trophy is mainly determined by the availability of nutrients (mainly P and N)
Eutrophication • The process of nutrient enrichment of a body, with attendant increases in organic matter, termed as Eutrophication. This is considered to be a natural aging process in lakes • Addition of P by human activities and the resulting aging of the lake is termed as Cultural Eutrophication.
Wetland Management Wetland functions: (1) Water storage and flood mitigation (2) Filtration of water and removal of suspended solids, bacteria, nutrients and toxic substances (3) Wildlife habitat (4) biogeochemical cycling of materials.
Created/Constructed Wetland • If damage to wetland is deemed unavoidable, new or improved wetlands must be created to offset the functions lost in the damaged wetlands. The creation or restoration of wetlands to compensate for damage to other wetlands is termed as compensatory mitigation. • Compensatory mitigation is intended to offset the loss of wetland functions by creating, restoring, or enhancing wetlands that will play a similar role before damage. • Created wetland refers to a wetland built for mitigation purposes, and constructed wetland denotes a wetland designed for pollutant removal from wastewater, urban and agricultural runoff, stormwater and mining wastes.
Bio-retention cell • Shallow depressions in the soil to which stormwater is directed for storage and to maximize infiltration. They are sometimes referred to as bio-infiltration cells, vegetated bio-filters, and rain gardens. • They are often mulched (for aesthetic values and water treatment) planted with native vegetation that promotes evapotranspiration.
Water is Already a Global Issue More than 2 billion people in 40 countries live in river basins under “water stress” Decreasing per-capita water availability - global population increased by a factor of 3 in 20th century, while water withdrawals increased by a factor of 7 As global population is expected to increase from 6 billion to 10 billion in 50 some years, demand on water will increase further
Failure with Past Approaches Sectoral, limited coordination, fragmented, uncoordinated development – inadequate to meet global challenges ! Supply-driven augmentation, top-down management, lack of demand management, subsidies led to inefficient investment, waste of water Restrictions on water transfers have prevented water from being allocated to the most beneficial use
What is IWRM ? IWRM: IWRM is a process which promotes the co-ordinated development and management of water, land and related resources in order to maximise the resultant economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystem. IWRM (as defined by global water partnership, GWP); “A participatoryplanning and implementation process, based on sound science, which brings together stakeholders, to determine how to meet society’s long-term needs for water and coastal resources while maintaining essential ecologicalservices and economic benefits.”