Module 3_merged.pdf

Importance of Safe Drinking Water on Public Health MODULE 1 PHILIPPINES’ WATER AND SANITATION CRISIS In the Philippines, 91% of the country’s estimated 100.7 million population have access to at least basic water services. Around 99% of the...

Importance of Safe Drinking Water on Public Health MODULE 1 PHILIPPINES’ WATER AND SANITATION CRISIS In the Philippines, 91% of the country’s estimated 100.7 million population have access to at least basic water services. Around 99% of the one-fifth wealthiest households are more likely to have access to basic water services; while only 80% of the poorest quintile do. Around 6 million Filipinos also still practice open defecation, and some 20 million lack access to basic sanitation facilities. HUMAN IS 60% WATER GLOBAL WATER DISTRIBUTION Only 1.2% of freshwater can be used as drinking water. KEY FACTS (according to WHO) Over 2 billion people live in water-stressed countries, which is expected to be exacerbated in some regions as result of climate change and population growth. Globally, at least 2 billion people use a drinking water source contaminated with feces. Microbial contamination of drinking-water as a result of contamination with feces poses the greatest risk to drinking-water safety. While the most important chemical risks in drinking water arise from arsenic, fluoride or nitrate, emerging contaminants such as pharmaceuticals, pesticides, per- and polyfluoroalkyl substances (PFASs) and microplastics generate public concern. Safe and sufficient water facilitates the practice of hygiene, which is a key measure to prevent not only diarrhea diseases, but acute respiratory infections and numerous neglected tropical diseases. Microbiologically contaminated drinking water can transmit diseases such as diarrhea, cholera, dysentery, typhoid and polio and is estimated to cause 485 000 diarrhea deaths each year. In 2020, 74% of the global population (5.8 billion people) used a safely managed drinking-water service – that is, one located on premises, available when needed, and free from contamination. IMPORTANCE OF SAFE DRINKING WATER Water and health Contaminated water and poor sanitation are linked to transmission of diseases such as cholera, diarrhea, dysentery, hepatitis A, typhoid and polio. Globally, 15% of patients develop an infection during a hospital stay, with the proportion much greater in low-income countries. Inadequate management of urban, industrial and agricultural wastewater means the drinking-water of hundreds of millions of people is dangerously contaminated or chemically polluted. IMPORTANCE OF SAFE DRINKING WATER Economic and Social Effects When water comes from improved and more accessible sources, people spend less time and effort physically collecting it, meaning they can be productive in other ways. Better water sources also mean less expenditure on health, as people are less likely to fall ill and incur medical costs and are better able to remain economically productive. Risk from water-related diseases, access to improved sources of water can result in better health, and therefore better school attendance, with positive longer-term consequences for their lives. DRINKING WATER QUALITY STANDARDS 5 REASONS WHY YOU NEED CLEAN DRINKING WATER Provides Nourishment Prevention of Diseases Helps in Getting Rid of Toxins Needed for Agriculture and Food Production Improved Sanitation Facilities DRINKING WATER QUALITY Common sources of drinking water contaminants include: Industry and agriculture - Organic solvents, petroleum products, and heavy metals from disposal sites or storage facilities can migrate into aquifers. Pesticides and fertilizers can be carried into lakes and streams by rainfall runoff or snowmelt, or can percolate into aquifers. DRINKING WATER QUALITY Common sources of drinking water contaminants include: Human and animal waste - Human wastes from sewage and septic systems can carry harmful microbes into drinking water sources, as can wastes from animal feedlots and wildlife. Major contaminants include Giardia, Cryptosporidium, and E. coli. DRINKING WATER QUALITY Common sources of drinking water contaminants include: Treatment and distribution - While treatment can remove many contaminants, it can also leave behind byproducts (such as trihalomethanes) that may themselves be harmful. Water can also become contaminated after it enters the distribution system, from a breach in the piping system or from corrosion of plumbing materials made from lead or copper. DRINKING WATER QUALITY Common sources of drinking water contaminants include: Natural sources -. Some ground water is unsuitable for drinking because the local underground conditions include high levels of certain contaminants. For example, as ground water travels through rock and soil, it can pick up naturally occurring arsenic, other heavy metals, or radionuclides. HEALTH CONSEQUENCE OF UNSAFE DRINKING WATER What makes water unsafe? CONTAMINATED WATER Germs Toxic chemicals Fertilizers Pesticides Worms Bacteria HEALTH CONSEQUENCE OF UNSAFE DRINKING WATER REFERENCES: https://www.who.int/news-room/fact-sheets/detail/drinking- water#:~:text=Water%20and%20health,individuals%20to%20preventable%20health%20risks. https://education.nationalgeographic.org/resource/earths-fresh-water https://www.unicef.org/philippines/press-releases/two-billion-people-lack-safe-drinking-water-more-twice-lack- safe-sanitation#:~:text=In%20the%20Philippines%2C%2091%25%20of,from%2062%25%20to%20100%25. https://water.org/our-impact/where-we-work/philippines/ https://www.epa.gov/report-environment/drinking-water Common Sources of Water Supply Module 2 WATER Most of the Earth is covered with water, and almost all of that is part of the salty oceans. Only a small portion of the Earth's water is fresh water. This includes such things as rivers, lakes, and groundwater. Freshwater is needed for drinking, farming, washing and other Almost all of that water is in the oceans. Ocean water is about 3.5% salt. Imagine that if the oceans dried up completely, enough salt would be left behind to build a 290-km tall and 1.6-km thick wall around the equator. Almost all of that salt would be ordinary table salt. Where does our water supply come from? The Earth has been recycling its water for 3 billion years. The process when water starts in a cloud, falls as rain, travels to the ocean, and then starts all over again is called the water cycle. WATER CYCLE Most of the water goes to the ocean, but the rest falls on land and eventually reaches the ocean by a river. Then, the water evaporates into the sky to form clouds. When the weather is just right, rain will fall and the whole cycle starts all over again. The water cycle never ends because the salty ocean water constantly supplies fresh water to the continents. Clouds Clouds are the pretty white fluffs you see in the sky. They are made up of tiny water drops. Sometimes, if the wind is fast enough, you can even watch the clouds move. Clouds can come in all sizes and shapes. They can be near the ground or way up high. Different types of clouds cause different kinds of weather. Sometimes clouds get dark and scary looking when a thunderstorm or tornado is about to start. At any given time, about half of Earth is covered by clouds. We would not have rain without clouds. Precipitation Precipitation is any form of water that falls to the Earth's surface. Precipitation is important because it helps maintain the atmospheric balance. Without precipitation, all of the land on the planet would be desert. Precipitation helps farmers grow crops and provides a fresh water supply for us to drink. Precipitation can also be damaging. Too much rain can cause severe flooding and lots of traffic accidents. Groundwater You have seen water in lakes, rivers, and oceans. But some water hides below the ground. It’s called groundwater. If you travel underground deep enough, you would find that the rocks around you are full with water. That’s deeper than the water table. This geologic layer of rocks is called an aquifer. In dry places, the water table might be very deep, but in moist places it is very shallow. When the water table is higher than the ground, there are streams, rivers, and lakes on the land surface. Water gets into an aquifer from the surface. Rainwater soaks into the ground and flows down to the water table. Rivers Rivers are very important to Earth because they are major forces that shape the landscape. Also, they provide transportation and water for drinking, washing, and farming. Rivers can flow on land or underground in deserts and seas. Rivers are part of the water cycle because water is carried downstream by rivers into oceans. They may come from springs, melting ice, lakes, or underground. They often start on a mountain. Lakes A lake is a body of water completely surrounded by land. Lakes can either by salty or fresh water. Most lakes are in places where glaciers used to exist. When a glacier moves forward, it carves away a deep valley and when the ice melts it forms a lake in the valley. Other lakes are formed in craters or when a river changes its course. WATER SUPPLY SUBSYSTEM The nature of the water source commonly determines the planning, design, and operation of the collection, purification, transmission and distribution works. The two major sources used to supply community and industrial needs comes from the surface water and groundwater. Streams, lakes, and rivers are the surface water sources while groundwater sources are those pumped from wells. Population and water consumption patterns are the prime factors that govern the quantity of water required and the source and the whole composition of water resource system. Factors that influence water consumption are industrial activity, meterage and water price, system management, standard of living, and climate. Figure: Water Supply Resource System Water SURFACE WATERBodies and Water Classification The Philippines is abundantly endowed with water resources. It has 18 major river basins, 421 principal rivers, about 79 natural lakes, 50,000 sq. km. groundwater reservoir area, and extensive coastline that stretches 17,460 km. Major Rivers Basins Figure: Major River Basins and Lakes in the Philippines  The largest river basin is the Cagayan River Basin in Cagayan Valley, with a drainage area of 27,494 sq km. It encompasses parts of Isabela, Cagayan, Nueva Viscaya, and Quezon Provinces. The second largest river basin is the Mindanao River Basin or the Rio Grande de Mindanao, which has a drainage area of 20 855 sq km and receives the waters from Pulangi and Allah Valley River Basins. Aside from fishing, the rivers are extensively used for transporting people and products. Major Lakes in the Philippines GROUNDWATER In terms of groundwater, the country has extensive reservoir with an aggregate area of about 50,000 sq km. It is recharged by rain and seepage from rivers and lakes. The Mines and Geoscience Bureau (MGB) reported that favorable groundwater basins are underlaid by about 100,000 sq km of various rock formations. These are located at: Northeast Luzon Central Luzon Laguna Lake basin Cavite-Batangas-Laguna basin Southeast Luzon Mindoro Island Negros Island Northeast Leyte Ormoc-Ka nanga basin Agusan-Davao basin Occidental Misamis basin Lanao-Bukidnon-Misamis basin  Limited water supply for all small-scale development is available in Panay, Cebu, Bohol, Samar, Palawan, Basilan Islands, Zamboanga Peninsula, and the Coastal Groundwater Basins. The MGB estimates that the country has an annual water supply of 30 billion cubic meters, which is almost 30 times the annual domestic water supply requirement, assuming an annual rainfall recharge of 0.3 meter. However, most groundwater development is within the upper 100 to 200 meters of various formations. In Metro Manila, the deeper artesian aquifers are at 200 to 400 meters depth because of salt water intrusion at the upper portion of the ground formation. WATER BODY CLASSIFICATION Water quality criteria are the benchmark against which monitoring data are compared to assess the quality of water bodies based on established classifications. As of 2019, EMB has classified water bodies, 794 are inland surface waters (consisting of 780 rivers and 14 lakes), while 110 are coastal and marine waters.  Marikina River in NCR has two classifications: Class A in its upstream and C downstream; Ipayo River in Region VI has three classifications: Class A in its upstream, B in midstream and C downstream; Lipadas River in Region XI has four classifications: Class AA in its upstream, A and B midstream and C downstream. Of the 794 classified inland surface water bodies, 7 have class AA portions; 279 with Class A; 272 with Class B; 420 with Class C, and 38 with Class D. The water bodies with Class AA portions (upstream) are as follows: Nagan River and Lake Ambulalakaw (CAR), Lawaan River (MIMAROPA), Ulian River (Region VI), Ginabasan River (Region VII) and Baganga Mahan-Ub River and Lipadas (Region XI). Overall, the MIMAROPA Region (Region IV-B) has the greatest number of classified water bodies with 96, followed by Region III with 73. NCR and BARMM have the least classified water bodies with only six each. Table: Distribution of Water Bodies per Classification and Beneficial Use, 2019 Table: Distribution of Classified Water Bodies per Region REFERENCES: https://www.who.int/news-room/fact-sheets/detail/drinking- water#:~:text=Water%20and%20health,individuals%20to%20preventable%20health%20risks. https://education.nationalgeographic.org/resource/earths-fresh-water https://www.unicef.org/philippines/press-releases/two-billion-people-lack-safe-drinking-water-more-twice-lack- safe-sanitation#:~:text=In%20the%20Philippines%2C%2091%25%20of,from%2062%25%20to%20100%25. https://water.org/our-impact/where-we-work/philippines/ https://www.epa.gov/report-environment/drinking-water https://emb.gov.ph/wp-content/uploads/2022/08/Final-National-WQSR-2014-2019_12Oct2020.pdf Assessment of Water Quality Module 3 Introduction to Water Quality The uses we make of water in lakes, rivers, ponds, and streams is greatly influenced by the quality of the water found in them. Water quality management is concerned with the control of pollution from human activity so that the water is not degraded to the point that it is no longer suitable for intended uses. Thus water quality management is a science of knowing how much is too much for a particular water body. The main objectives are to protect the intended uses of a water body while using water as an economic means of waste disposal within the constraints of its assimilative capacity, restore and maintain the chemical, physical and biological integrity of nations waters, protect and propagate fish, shellfish and wildlife and provide for recreation in and out of the water. To know how much waste can be tolerated (or assimilated) by a water body, we must know the type of pollutants discharged and the manner in which they affect water quality. We must know how water quality is affected by natural factors such as mineral heritage of the watershed, the geometry of the terrain, and the climate of the region. Water Pollutants and Their Sources Point Sources Domestic sewage and industrial wastes are called point sources because they are generally collected by a network of pipes and conveyed to a single point of discharge into the receiving water. Point source pollution can be reduced or eliminated through waste minimization and proper wastewater treatment prior to discharge to a natural body. Non-Point Sources Urban and agricultural runoff are characterized by multiple discharge points. Much of the non-point source pollution occurs during rainstorms resulting in large flow rates that make treatment even more difficult. Reduction of agricultural non-point source pollution generally requires changes in land use practices and improved education. Figure: Major Pollutant categories and principal sources of pollutants 1. Oxygen Demanding Material Anything that can be oxidized in the receiving water with the consumption of dissolved molecular oxygen is termed oxygen-demanding material. Usually biodegradable organic matter but also includes certain inorganic compounds. The consumption of dissolved oxygen (DO) poses a threat to fish and other higher forms of aquatic life that must have oxygen to live. Oxygen-demanding materials in domestic sewage come primarily from human waste and food residue as well as from industries like food processing and paper making. Almost any naturally occurring organic matter, such as animal droppings, crop residues, or leaves, which get into the water from non-point sources, contribute to the depletion of DO. 2. Nutrients Nitrogen and phosphorous, two nutrients of primary concern, are considered pollutants. All living things require these nutrients for growth and they should be present in rivers and lakes to support natural food chain.  However, when nutrient levels become excessive and the food web is grossly disturbed, which causes some organisms to proliferate at the expense of others. Excessive nutrients often lead to large growths of algae, which in turn become oxygen-demanding material when they die. Some major sources of nutrients are phosphorous-based detergents, fertilizers, and food- processing wastes. 3. Pathogenic Organisms Microorganisms found in wastewater include bacteria, viruses, and protozoa excreted by diseased persons or animals. When discharged in surface waters, they make water non-potable and if concentration is sufficiently high, the water may also be unsafe for fishing and swimming. Certain shellfish can be toxic because they concentrate pathogenic organisms in their tissues. 4. Suspended Solids Organic and inorganic particles that are carried by the wastewater into a receiving water are termed suspended solids.  When the speed of the water is reduced by flowing into a lake, many of these particles settle to the bottom as sediment. It includes eroded soil particles carried by water. Colloidal particles, which do not settle readily, cause turbidity found in many surface waters. Organic suspended solids may also exert an oxygen demand. Inorganic suspended solids are discharged by some industries but result mostly from soil erosion, which is particularly bad in areas of logging, strip mining, and construction activity. As excessive sediment loads are deposited into lakes and reservoirs, the usefulness of the water is reduced. In streams, sediment from mining and logging operations destroy many living places for aquatic organisms. 5. Salts Although most people associate salty water with oceans and salt lakes, all water contains some salt. Problem arises when the salt concentration in normally fresh water increases to the point where the natural population of plants and animals is threatened or the water is no longer useful for public water supplies or irrigation.  Salts are often measured by evaporation of a filtered water sample. The salts and other things that don’t evaporate are called total dissolved solids (TDS). High concentration of salts are discharged by many industries. In irrigation, water picks up salt every time it passes through the soil on its way back to the river. 6. Toxic Metals and Toxic Organic Compounds. Agricultural runoff often contains pesticides and herbicides that have been used in crops. Urban runoff is a major source of zinc in water bodies. Zinc comes from tire wear. Many industrial wastewaters contain either toxic metals or toxic organic substances that if discharged in large quantities, may render a body of water nearly useless. Many toxic compounds are concentrated in the food chain, making fish and shellfish unsafe for human consumption. 7. Heat Higher water temperatures disposed by industries increase the rate of oxygen depletion in areas where oxygen demanding wastes are present. Also, many commercial fish live only in cool water. Water Quality Management in Rivers Objective of Water Quality Management - To control the discharge of pollutants so that water quality is not degraded to an unacceptable extent below the natural background level. METHODOLOGY: Identifying and quantifying the pollutants to be discharged Determining the background water quality of the receiving water which would be present without human intervention Predicting the impact of the pollutant on water quality Deciding the levels acceptable for intended uses of the water. - The impact of pollution on a river depends both on the nature of the pollutant and the unique characteristic of the individual river. IMPORTANT CHARACTERISTICS: 1. Volume and speed of water flowing in the river 2. Depth of river 3. Type of bottom 4. Surrounding vegetation 5. Climate of the region 6. Mineral heritage of watershed 7. Land use patterns 8. Types of aquatic life in the river Effect of Oxygen-Demanding Wastes on Rivers Oxygen-demanding wastes and nutrients are common and have a profound impact on almost all types of rivers. The introduction of oxygen-demanding material, either organic or inorganic, into the river causes depletion of the dissolved oxygen in the water which poses a threat to fish and other higher forms of aquatic life if the oxygen 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 will be required to degrade the waste. Oxygen-demanding materials are commonly measured by determining the amount of oxygen consumed during degradation in a manner approximating degradation in natural waters. Determination of Oxygen Demand 1. Theoretical Oxygen Demand (ThOD) - The amount of oxygen required to oxidize a substance to carbon dioxide and water, which may be calculated by stoichiometry if the chemical composition of the substance is known. 2. Chemical Oxygen Demand (COD) - A measured quantity that does not depend on knowledge of the chemical composition of the substances in the water. - In the COD test, a strong chemical oxidizing agent (chromic acid) is 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. 3. Biochemical Oxygen Demand (BOD) - The oxygen consumed if the oxidation of an organic compound is carried out by microorganisms using the organic matter as a food source. - The actual BOD is less than the ThOD due to the incor-poration of some of the carbon into new bacterial cells. - The test is a bioassay that utilizes microorganisms in conditions similar to those in natural water to measure indirectly the amount of biodegradable organic matter present. - A water sample is inoculated with bacteria that consume the biodegradable organic matter to obtain energy for their life processes. - Because the organisms utilize oxygen in the process of consuming waste, the process is called aerobic decomposition. - The greater the amount of organic matter present, the greater the amount of oxygen utilized. - The BOD test is an indirect measurement of organic matter because we actually measure only the change in the dissolved oxygen concentration caused by the microorganisms as they degrade the organic matter. - BOD test is the most widely used method of measuring organic matter because of the direct conceptual relationship between BOD and oxygen depletion in receiving waters. - When a water sample containing degradable organic matter is placed in a closed container and inoculated with bacteria, the oxygen consumption typically follows the following pattern: - During the first few days the rate of oxygen depletion is rapid because of the high concentration of organic matter present. - As the concentration of organic matter decreases, the rate of oxygen consumption also decreases. - The rate at which oxygen is consumed is directly proportional to the concentration of degradable organic matter remaining at any time. BOD curve can be described mathematically as a first-order reaction. 𝑑𝐿𝑡 = −𝑟𝐴 𝑑𝑡 where, Lt = oxygen equivalent of the organics remaining at time t, mg/L -rA = -kLt k = reaction rate constant, d-1 where, Lo = oxygen equivalent of the organics at time = 0 - Rather than the Lt, our interest is in the amount of oxygen used in the consumption of the organics (BODt). - Lo is often referred to as the ultimate BOD, that is the maximum oxygen consumption possible when the waste has been completely degraded.  (in base 10 form) where, Example No. 1: If the BOD3 of a waste is 75 mg/L and the reaction rate constant, k is 0.345 day-1, what is the ultimate BOD as well as the dissolved oxygen left? - The ultimate BOD (Lo) is defined as the maximum BOD exerted by the waste. - We can assume that when the BOD curve is approximately horizontal, the ultimate BOD has been achieved. We would take this to be at about 35 days. - Although the ultimate BOD best expresses the concentration of degradable organic matter, it does not, by itself, indicate how rapidly oxygen will be depleted in a receiving water. - While the ultimate BOD increases in direct proportion to the concentration of degradable organic matter, the numerical value of the rate constant is dependent of the: 1. Nature of waste. - Simple sugars and starches are rapidly degraded and will therefore have a very large BOD rate constant. - Cellulose (i.e. toilet paper) degrades much more slowly, and hair and fingernails are almost undegradable. Table Typical values for BOD rate constant.  2. Ability of organisms in the system to utilize waste. - In a natural environment receiving a continuous discharge of organic waste, the population of organisms which can most efficiently utilize waste will predominate. - The BOD test should be conducted with organisms which have acclimated to the waste so that the rate constant deter- mined in the laboratory can be compared to that in the river. 3. Temperature. - Most biological processes speed up as the temperature increases and slow down as the temperature drops. Because oxygen utilization is caused by metabolism of microorganisms, the rate of utilization is similarly affected by temperature. - Laboratory testing is done at a standard temperature of 20oC and the BOD rate constant is adjusted to the receiving- water temperature.  where, T = temp. of interest kT = BOD rate constant at temp. of interest, d-1 k20 = BOD rate constant at 20 oC, d-1 Q = temp. coefficient 1.135 for temp. 4 to 20 oC 1.056 for temp. above 20 oC Example No. 2: A waste is being discharged into a river that has a temperature of 10 oC. What is the dissolved oxygen concentration after four days if the four day BOD is 125 mg/L and the rate constant determined in the laboratory under standard conditions is 0.415 d-1 (base e)? Laboratory Measurement of BOD In order to have as much consistency as possible, it is important to standardize testing procedures when measuring BOD. The detailed procedures can be found in Standard Methods for the Examination of Water and Wastewater. Procedure: A special 300 ml BOD bottle is completely filled with a sample of water that has been appropriately diluted and inoculated with microorganisms. Samples require dilution because the only oxygen available to the organisms is dissolved in the water. The most oxygen that can be dissolved is about 9 mg/L, so the BOD of the diluted sample should be between 2 and 6 mg/L. Samples are diluted with a special dilution water that contains all of the trace elements required for bacterial metabolism so that degradation of organic matter is not limited by lack of bacterial growth.  The appropriate sample size to use can be determined by dividing 4 mg/L (mid-point of the desired range of diluted BOD) by the estimated BOD concentration in the sample being tested. Example No. 8: The BOD of a wastewater sample is estimated to be 180 mg/L. What volume of undiluted sample should be added to a 300 ml bottle? What are the sample size and dilution factor using this volume? Assume that 4 mg/L BOD can be consumed in the BOD bottle. 2. Blank samples containing only the inoculated dilution water are also placed in BOD bottles and stoppered.  Blanks are required to estimate the amount of oxygen consumed by the added inoculum in the absence of the sample. 3. The stoppered BOD bottles containing diluted samples and blanks are incubated in the dark at 20oC for the desired number of days. For most purposes, a standard time of 5 days is used. 4. After the desired number of days has elapsed, the samples and blanks are removed from the incubator and the dissolved oxygen concentration in each bottle is measured. The BOD of the undiluted sample is then calculated. where, DOb,t = dissolved oxygen conc. in blank t days after incubation, mg/L DOs,t = dissolved oxygen conc. in sample t days after incubation, mg/L  Example No. 9: What is the BOD5 of the wastewater sample of Example 8 if the DO values for the blank and diluted sample after five days are 8.7 and 4.2 mg/L respectively? DO Sag Curve The concentration of dissolved oxygen in a river is an indicator of the general health of the river. All rivers have some capacity for self purification. As long as the discharge of oxygen-demanding wastes is well within the self-purification capacity, the DO level will remain high and a diverse population of plants and animals will live. When DO drops below 4 mg/L, most fishes will have been driven out. If DO is completely removed, fish and other animals are killed and extremely noxious conditions result. The water becomes blackish and foul smelling as the sewage and dead animal life decompose under anaerobic condition.  One of the major tools of water quality management in rivers is the ability to assess the capability of a stream to absorb a waste load. This is done by determining the profile of DO concentration downstream from a waste discharge. This profile is called DO Sag Curve because the DO concen-tration dips as oxygen-demanding materials are oxidized and then rises again further downstream as the oxygen is replenished from the atmosphere. Factors Contributing to Oxygen Depletion 1. BOD of the of the waste discharge and the BOD already present in the river upstream of the waste discharge. 2. DO in the waste discharge is usually less than that of the river. 3. Non-point source pollution. 4. Respiration of organisms living in the sediments, which is called benthic demand. On the other hand, the only significant sources of oxygen are (1) reaeration from the atmosphere and (2) photosynthesis of aquatic plants. Mass-Balance Approach Simplified mass balances help us understand and solve the DO sag curve problem. Three consecutive mass balances may be used to account for initial mixing of the waste stream and the river. DO, BOD, and temperature all change as a result of mixing of the waste and the river. Once these are accounted for, the DO sag curve may be viewed as a non-conservative mass balance.  Water Quality Management in Lakes Oxygen-demanding wastes can also be important lake pollutants, especially when the waste is discharged to a contained area as a bay. Phosphorous so dominates other pollutants in controlling water quality in the vast majority of lakes. Knowledge of lake systems is essential to understanding the role of phosphorous in lake pollution. The study of lakes is called limnology. Lake Stratification Nearly all lakes in the temperate zone become stratified during the summer and overturn in the fall due to changes in the water temperature that result from the annual cycle of air temperature changes. During the summer, the surface water of a lake is heated both indirectly by contact with warm air and directly by sunlight. Warm water, being less dense than cool water, remains near the surface, until mixed downward by turbulence.  Turbulence extends only a limited distance below water surface, the result is an upper layer of well-mixed, warm water, called epilimnion, floating on the lower water which is poorly mixed and cool, called hypolimnion. Because of good mixing, the epilimnion will have good amount of DO while hypolimnion will have lower DO. The boundary is called thermocline because of the sharp temperature change that occurs within a relatively short distance. It may be defined as a change in temperature with depth that is greater than 1 oC/m. Biological Zones Lakes contain several distinct zones of biological activity, largely determined by the availability of light and oxygen. The most important biological zones are the euphotic, littoral, and benthic zones. 1. Euphotic Zone The upper layer of water through which sunlight can penetrate is called the euphotic zone. All plant growth occurs in this zone (i.e. algae in deep water and rooted plants in shallow water near shore). The depth of the euphotic zone is determined by the amount of turbidity blocking sunlight penetration. In the euphotic zone, plants produce more oxygen by photosynthesis than they remove by respiration. 2. Profundal Zone Below the euphotic zone lies the profundal zone. The transition between the two zones is called the light compensation level. The light compensation level corresponds roughly to a depth at which the light intensity is about one percent of unattenuated sunlight. 3. Littoral Zone The shallow water near the shore in which rooted water plants can grow is called the littoral zone. The extent of the littoral zone depends on the slope of the lake bottom and the depth of the euphotic zone. The littoral zone cannot extend deeper than the euphotic zone. 4. Benthic Zone The bottom sediments comprise the benthic zone. As organisms living in the overlying water die, they settle to the bottom where they are decomposed by organisms living in the benthic zone. Lake Productivity The productivity of a lake is a measure of its ability to support a food web. Algae form the base of this food web, supplying food for the higher organisms. A lake’s productivity may be determined by measuring the amount of algal growth that can be supported by the available nutrients. Increased productivity, however, generally results in reduced water quality because of undesirable changes that occurs as algal growth increases. Because the important role productivity plays in determining water quality, it forms a basis for classifying lakes. 1. Oligotrophic Lakes Oligotrophic lakes have a low level of productivity due to a severely limited supply of nutrients to support algal growth. The water is clear enough that the bottom can be seen at considerable depths. As a result, euphotic zone often extends into the hypolimnion. 2. Mesotrophic Lakes Lakes which are intermediate between oligotrophic and eutrophic are called mesotrophic. Although substantial depletion of oxygen may have occurred in the hypolimnion, it remains aerobic 3. Eutrophic Lakes Eutrophic lakes have a high productivity because of an abundant supply of algal nutrients. The algae cause the water to be highly turbid, so the euphotic zone may extend only partially into the epilimnion. As the algae die, they settle to the lake bottom where they are decomposed by benthic organisms. Eutrophic lakes support only warm-water fish. Highly eutrophic lakes may have large mats of floating algae that typically impart unpleasant tastes and odors to the water. 4. Senescent Lakes These are very old, shallow lakes which have thick organic sediments and rooted water plants in great abundance. These lakes will eventually become marshes. Eutrophication Eutrophication is a natural process in which lakes gradually become shallower and more productive through the introduction and cycling of nutrients. Thus, oligotrophic lakes gradually pass through the mesotrophic, eutrophic, and senescent stages, eventually filling completely. The time for this process to occur depends on the original size of the lake and on the rate at which sediments and nutrients are introduced. Cultural eutrophication is caused when human activity speeds the processes naturally occurring by increasing the rate at which sediments and nutrients are added to the lake. Water quality management in lakes is primarily concerned with slowing eutrophication to at least the natural rate. Algal Growth Requirements All algae require macronutrients, such as carbon, nitrogen, and phosphorus, and micronutrients, such as trace elements. For algae to grow, all nutrients must be available. Lack of any one nutrient will limit the total algal population. 1. Carbon Algae obtain their carbon from carbon dioxide dissolve in the water. Immediately available carbon is determined by the alkalinity of the water. However, as carbon dioxide is removed from water, it is replenished from the atmosphere. When algae are either consumed by higher organisms or die and decompose, the organic carbon is oxidized back to carbon dioxide which returns either to the water or to the atmosphere to complete the carbon cycle. 2. Nitrogen Nitrogen in lakes is usually in the form of nitrate (NO3) and comes from external sources by way of inflowing streams or groundwater.  When taken up for algal growth, the nitrogen is chemically reduced to amino-nitrogen (NH2) and incorporated into organic compounds. When dead algae undergo decomposition, the organic nitrogen is released to the water as ammonia (NH3). The ammonia is then oxidized back to nitrate by bacteria in the same nitrification process. Nitrogen cycles from nitrate to organic nitrogen, to ammonia, and back to nitrate as long as the water remains aerobic. However, in anaerobic sediments, and in the hypolimnion of eutrophic lakes, when algal decomposition has depleted the oxygen supply, nitrate is reduced by anaerobic bacteria to nitrogen gas (N2) and lost from the system in a process called denitrification. 3. Phosphorous Phosphorus in lakes originates from external sources and is taken up by algae in the inorganic form and incorporated into organic compounds. During algal decomposition, phosphorus is returned to the inorganic form. Control of Phosphorous in Lakes Since phosphorus is usually the limiting nutrient, control of cultural eutrophication must be accomplished by reducing the input of phosphorus to the lake. Other strategies for reversing or slowing the eutrophication process, such as precipitating phosphorus with additions of aluminum (alum) or removing phosphorus-rich sediments by dredging. To be able to reduced phosphorus inputs, it is necessary to know the sources of phosphorus and the potential for their reduction. The natural source of phosphorus is the weathering of rock. Phosphorus released from the rock can enter the water directly, but more commonly it is taken up by plants and enters the water in the form of dead plant matter. 1. Municipal and Industrial Wastewater All municipal sewerage contains phosphorus from human excrement. Many industrial wastes are high in this nutrient.  In these cases, the only effective way of reducing phosphorus is through advanced waste treatment processes. Municipal wastewaters also contain large quantities of phosphorus from detergents containing polyphosphate, which is a chain of phosphate ions linked together. The polyphosphate binds with hardness in water to make the detergent a more effective cleaning agent. 2. Septic Tank Seepage The shores of many lakes are dotted with homes and summer cottages, each with its own septic tank and tile field for waste disposal. As treated wastewater moves through the soil toward the lake, phosphorus is absorbed by soil particles, especially clay. Thus, during the early life of the tile field, very little phosphorus gets to the lake. However, with time, the capacity of the soil to absorb phosphorus is exceeded and any additional phosphorus will pass on into the lake, contributing to eutrophication.  To prevent phosphorus from reaching the lake, it is necessary to put the tile field far enough from the lake that the adsorption capacity of the soil is not exceeded. If this is not possible, it may be necessary to replace the septic tanks and tile fields with a sewer to collect the wastewater and transport it to a treatment facility. 3. Agricultural Runoff Because phosphorus is a plant nutrient, it is an important ingredient in fertilizers. As rain water washes off fertilizers field, some of the phosphorus is carried into streams and then into lakes. Most of the phosphorus not taken up by growing plants is bound to soil particles. Bound phosphorus is carried into streams and lakes through soil erosion. Waste minimization can be applied to the control of phosphorus loading to lakes from agricultural fertilization by encouraging farmers to fertilize more often with smaller amounts and to take effective action to stop soil erosion. Water Quality Management in Groundwater REFERENCES: https://www.who.int/news-room/fact-sheets/detail/drinking- water#:~:text=Water%20and%20health,individuals%20to%20preventable%20health%20risks. https://education.nationalgeographic.org/resource/earths-fresh-water https://www.unicef.org/philippines/press-releases/two-billion-people-lack-safe-drinking-water-more-twice-lack- safe-sanitation#:~:text=In%20the%20Philippines%2C%2091%25%20of,from%2062%25%20to%20100%25. https://water.org/our-impact/where-we-work/philippines/ https://www.epa.gov/report-environment/drinking-water https://emb.gov.ph/wp-content/uploads/2022/08/Final-National-WQSR-2014-2019_12Oct2020.pdf https://www.usgs.gov/special-topics/water-science-school/science/groundwater-quality#overview https://groundwater.ucdavis.edu/files/136273.pdf  If you’ll need drinking water, Bring your own refillable Water Characteristics and Purchase a drinking water drinking water Drinking Water Quality Module 4 TAP WATER IS NOT POTABLE Ask for service water Unless, 1 2 Annual Poverty Indicators Survey and Water Quality Testing Module (PSA, 2017) 3 4  Main sources of drinking water contamination 5 6 Problems Arising From RESOURCE TASTE AND ODOR While the natural quality of drinking water depends primarily on the geology and soils of the catchment, other Odor problems are categorized according to the origin of the substance causing the problem. Substances can be present factors such as land use and disposal of pollutants are also important. In general, impermeable rocks such as granite in the raw water, be added or created during water treatment, arise within the distribution system or arise in the are associated with turbid, soft, slightly acidic and naturally colored waters. Groundwater resources associated with domestic plumbing system. Of course, the quality of the raw water will often contribute to the production of odors hard rock geology are localized and small, so supplies come mainly from surface waters such as rivers and during treatment and distribution. impounding reservoirs. The main contaminants prior to treatment are: Common causes of odor and taste in drinking water. 1. Decaying vegetation : algae produce fishy, grassy and musty odors as they decay, and certain species can cause serious organoleptic problems when alive. 2. Molds and actinomycetes: produce musty, earthy or moldy odors and tastes; they tend to be found where water is left standing in pipework and also when the water is warm –they are frequently found in the plumbing systems of large buildings such as offices and flats, but are also associated with water-logged soil and unlined boreholes. 3. Iron and sulphur bacteria: both bacteria produce deposits which release offensive odors as they decompose. 4. Iron, manganese, copper and zinc : the products of metallic corrosion all impart a rather bitter taste to the water. 7 8  Problems Arising From WATER TREATMENT 5.. Sodium chloride : excessive amounts of sodium chloride will make the water taste initially flat or dull, then progressively salty or brackish. 6. Industrial wastes : many wastes and by-products produced by industry can impart a strong medical or chemical taste or odor to the water – phenolic compounds which form chlorophenols on chlorination are a particular problem. 7. Chlorination: chlorine by itself does not produce a pronounced odor or taste unless the water is overdosed during disinfection; chlorine will react with a wide variety of compounds to produce chlorinated products many of which impart a chlorinous taste to the water. Chlorine and fluoride 9 10 Problems Arising From the DISTRIBUTION Problems Arising in Home Plumbing Situations SYSTEM Water quality problems are commonly associated with the deterioration of the distribution network. Iron pipes can The major problems arising within the house are elevated concentrations of lead, copper and zinc, odor and taste, lead to discoloration of water, elevated iron concentrations and sediment problems. Asbestos cement, once widely fibers from loft insulation, corrosion and pathogens. However, most home-based problems are associated with used for water mains, releases fibers of asbestos into the water. corrosion of pipe-work and storage tanks leading to contamination of water by lead, copper, zinc or iron. Polycyclic(polynuclear) aromatic hydrocarbons (PAHs) also occur in soot, vehicle exhausts and in the combustion Corrosion The rate of corrosion rapidly increases at higher temperatures and products of hydrocarbon fuels. when the water is acidic. Animals and Biofilm. Bacteria and fungi are common in water mains. They grow freely in the water, and more importantly form films or slime growths on the inside of the pipe, which make them far more resistant against attack from residual chlorination. Biofilms can significantly affect the microbial safety of drinking water while in an operational sense slime formation is undesirable as it increases the frictional resistance in the pipes, thereby Lead In areas where soft acidic water resources are used elevated lead levels in drinking waters are common. It increasing the cost of pumping water through the system. was widely used for this purpose because being so malleable it allowed slight movement of the pipework without fracture, rather like the modern plastic pipes used today. Lead is odorless, tasteless and colorless when in solution, so that even relatively high concentrations of lead in drinking water are undetectable by the consumer unless chemically analyzed. Lead is not removed by boiling and in fact is concentrated, with elevated levels found in kettles that are not fully emptied before refilling. Copper is normally present in natural waters at low concentrations, except in metalliferous areas. Its presence in drinking water is almost always due to the attack of copper plumbing. 11 12  Water Related Diseases Diseases closely associated with water are classified according to their mode of transmission and the form of infection into four different categories: waterborne, water-washed, water-based and water-related diseases. Microbial contamination is the most critical risk factor in drinking 1. Waterborne diseases. These diseases occur where a pathogen is transmitted by ingestion of contaminated water. water quality with the potential for widespread waterborne The classical waterborne diseases are mainly low-infective dose infections, such as cholera and typhoid, with all disease. Illness derived from chemical contamination of drinking the other diseases high-infective dose infections that include infectious hepatitis and bacillary dysentery. All waterborne diseases can also be transmitted by other routes, which permit fecal material to be ingested. water supplies is negligible when compared to that due to 2. Water-washed diseases. These include fecal – orally spread disease or disease spread from one person to another microbial pathogens ( Galbraith et al. , 1987; Herwaldt et al. , facilitated by a lack of an adequate supply of water for washing. The incidence of all these diseases will fall if 1992 ). Globally 5 million people die each year from disease and adequate supplies of washing water, regardless of microbial quality, are provided. These are diseases of mainly tropical areas, and include infections of the intestinal tract, the skin and eyes. illness caused by unsafe water sup- 3. Water-based infections. These diseases are caused by pathogenic organisms which spend part of their lifecycle in plies and inadequate sanitation, with an estimated 200 million aquatic organisms. All these diseases are caused by parasitic worms, with the severity of the infection depending cases of water-related diarrheal illness leading to 2.1 million on the number of worms infesting the host. deaths annually. 4. Water-related diseases. These are caused by pathogens carried by insects that act as mechanical vectors and which live near water. All these diseases are very severe and the control of the insect vectors is extremely difficult. 13 14 Disease Caused by Drinking Polluted Water Waterborne Pathogens Primary Bacterial Pathogens Salmonella. The various serotypes that make up the genus Salmonella are the most important group of bacteria affecting the public health of both humans and animals, wild, domestic and farm animals often acting a reservoirs of human salmonellosis. Water resources can become contaminated by raw or treated wastewater, as well as by effluents from abattoirs and animal-processing plants. Typical symptoms of salmonellosis are acute gastroenteritis with diarrhea, an association with abdominal cramps, fever, nausea, vomiting, headache and, in severe cases, even collapse and possible death. Shigella causes bacterial dysentery or shigellosis and is one of the most frequently diagnosed causes of diarrhea. The species of this bacterial genus are rather similar in their epidemiology to Salmonella except they rarely infect animals and do not survive quite so well in the environment. Cholera fatal bacterial disease of the small intestine, typically contracted from infected water supplies and causing severe vomiting and diarrhea. An infected person or symptomless carrier of the disease excretes up to 1013 bacteria daily, enough to theoretically infect 107people! Up to 106 – 107 organisms are required to cause the illness; hence cholera is not normally spread by person-to-person contact. It is transmitted primarily by drinking contaminated water, but also by eating food handled by a carrier, or which has been washed with contaminated water, and is regularly isolated from surface waters 15 16  Mandatory drinking water quality parameters and their standard values REFERENCES: https://www.who.int/news-room/fact-sheets/detail/drinking- Parameter Standard values water#:~:text=Water%20and%20health,individuals%20to%20preventable%20health%20risks. https://education.nationalgeographic.org/resource/earths-fresh-water Thermotolerant coliform or E. coli MTFT: