It’s not a widely published fact, but that’s no reason why it should not be a widely acknowledged problem. The world’s supply of fresh water is slowly running dry. Forty percent of the world’s population is already reeling under the problem of scarcity.
Most of the diseases plaguing the world are water-borne. And while there is a child born every eight seconds in America, there is a life taken every eight seconds by some water-borne disease in other parts of the world.
Is it the lopsided distribution of fresh water that is causing climate change, or is it the climatic change that is causing this lopsided distribution? The fact is that there is a significant climate change, and as a consequence of this change, some regions are becoming drier while others are getting wetter. Some parts of the world are experiencing greater desertification, while others are suffering category 4 and 5 hurricanes.
According to the United Nations, water scarcity is amongst the most serious crises facing the world. And things are only getting worse.
Uzbekistan and Kazakhstan of the erstwhile USSR, Chile, Mexico, Paraguay, Argentina, Peru and Brazil in Latin America, parts of China and the Middle East especially Iran, and more than 25 countries of Africa are all suffering from varying degrees of desertification.
Global weather has gone awry. It is making poor countries poorer. Countries that are already facing drought and famine are getting less and less water. For how long can these countries run on dry?
Nowhere is the situation worse than in Africa. Almost 40 million people in 19 countries are facing imminent food shortage. Much of the livestock there will perish. The growing water shortage will make food scarcer, potable water less accessible and water-borne diseases even more rampant. And the number of people who will suffer all this is expected to touch more than 500 million by the 2025. And the global consequence: A greater dependence on international aid.
And this problem is not just limited to Africa. No one can tell which part of the globe will be next.
Blame this on nature. It’s most convenient. But fact is, much of the blame belongs to increasing consumption and improper usage.
At every opportunity nature reminds us by what it does and what it doesn’t, that it is one of the forces we have little control over. So there’s no way we can stop the rain or start it. But what we can do is become more water-efficient - get more from every gallon of water. And the only way to do this is to recycle and reuse waste water. Water is the giver of life. It has no substitute. And every drop counts!
Many believe that the next world war is likely to be fought on the issue of water. Even though the world is two-thirds water, most of it is not potable, and much of it is not usable for any other purpose as well.
And we are busy consuming and contaminating whatever is left of it, as if it were a non-depletable resource. In this blog, I shall make an attempt to identify ways to make the best use of water, an increasingly scarce resource, by recovering it from wastewater, whether we intend to reuse the water so recovered or let it just charge our ground water reserves.
This is aimed at a wide cross-section of people involved in taking corrective action across the world policy makers, administrators, municipal engineers & scientists, engineers & administrators in industries vested with the responsibility of wastewater treatment and management, industrial & residential property builders, academics, students and just about everyone who cares about posterity.
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Organic Matter:
Vegetable Plants, animals and human beings are the sources for origination of natural or synthetic organic compounds. Human excreta, paper products, detergents, cosmetics, food, agricultural products, wastes from commercial activities and wastes from industrial sources are organic in origin and considerable in quantity.
Organic compounds generated from the above sources are a combination of carbon, hydrogen, oxygen, nitrogen, sulfur and other trace elements. Organic compounds such as proteins, carbohydrates, and fats are degradable by organisms, however they can cause pollution.
Large concentration of degradable organics in wastewater is dangerous to lakes, streams, and oceans, because organisms consume dissolved oxygen in water to break down the wastes. This can reduce or deplete the supply of oxygen in the water needed by aquatic life, resulting in fish kills, increasing the odors, and overall deterioration of water quality.
Some organic compounds are more stable than others and cannot be quickly broken down by organisms. This poses an additional challenge for treatment. This is true with many synthetic organic compounds developed for agriculture and industry. Some of the synthetic organic compounds that belong to pesticides, herbicides, dyes, pigments, fried oils, and fried meats are toxic to humans, fish, and aquatic plants and often are disposed off improperly in drains or carried in storm-water. In receiving water bodies, they kill or contaminate fish, making them unfit to eat. They also can reduce the efficiency of the processes in treatment.
Gases:
What are the sources for gases in wastewater? Certain gases in wastewater can cause odors, affect treatment, so are potentially dangerous. Methane gas, for example, is a byproduct of anaerobic biological treatment and is highly combustible. Special precautions need to be taken near septic tanks, manholes, treatment plants, and other areas where wastewater gases can collect.
The gases hydrogen sulfide and ammonia can be toxic and pose asphyxiation hazards. Also, ammonia as a dissolved gas in wastewater is dangerous to fish. Both gases emit odors, which can be a serious nuisance. Unless effectively controlled or minimized by design and location, wastewater odors can affect the mental wellbeing and quality of life of residents. In some cases, odors can even lower property values and affect the local economy.
Oil & Grease:
Animal fat, vegetable and petroleum oils are not quickly broken down by bacteria and can cause permanent pollution in receiving environments. When large amounts of oils and greases are discharged to receiving waters from community systems, they may float to the surface and harden, causing aesthetically unpleasing conditions. The floating oils and grease decreases the oxygen transfer efficiency of water causing septic condition.
They also can bind with solid proteins, carbohydrate and other materials, causing foul odors, attracting flies, mosquitoes and other disease vectors.
Solids:
Solid materials in wastewater can consist of organic and/or inorganic materials. The solids must be significantly reduced by treatment or they would increase BOD when discharged to receiving waters and provide places for microorganisms to escape disinfection. They can also clog soil absorption fields in onsite systems.
Settleable solids - certain substances, such as sand, grit, and heavier organic and inorganic materials settle out from the rest of the wastewater stream during the preliminary stages of treatment. On the bottom of settling tanks and ponds, organic material makes up a biologically active layer of sludge that aids in treatment.
Suspended solids - materials that resist settling may remain suspended in wastewater. Suspended solids in wastewater must be treated, or they will clog soil absorption systems and reduce the effectiveness of disinfection systems.
Dissolved solids - small particles of certain wastewater materials can dissolve like salt in water. Microorganisms in wastewater consume some dissolved materials, but others, such as heavy metals, are difficult to remove by conventional treatment. Excessive amounts of dissolved solids in wastewater can have adverse effects on the environment.
Heavy metals:
Do you suspect heavy metals to be present in sewage? Municipal wastewater also contains a variety of potentially toxic elements such as arsenic, cadmium, chromium, copper, lead, mercury, zinc, etc. Even if toxic materials are not present in concentrations likely to affect humans, they might well be at phytotoxic levels, which would limit their agricultural use. However, from the health point of view, the greatest concern in the agricultural use of wastewater are the pathogenic micro and macro organisms.
Water that is polluted by humans, through residential, industrial or commercial activity, is called wastewater. These pollutants are often toxic substances and a hazard to the health of the people who consume or use it. It’s a hazard to the environment if left to sink into the ground. This gives rise to the need for treatment of wastewater, in order to remove the pollutants from water, and make it safe for consumption, and use. It must be treated even if merely let out in the environment, say to sink into the ground or to mix with sea water.
Why You Should Conserve Water?
Water conservation also indirectly helps in maintaining the water quality. Excessive water drawing (exceeding the water holding capacity of the soil) from ground sources allows ground water contamination from neighboring areas or sea. So, avoid unnecessary water drawing from ground sources. The volume of wastewater discharge can be reduced substantially through conservation of water.
This is a good idea for a number of reasons:
Significant reduction in wastewater flows also can save on personnel costs and can eliminate or postpone the need to upgrade or expand treatment facilities. It lowers sewer charges and taxes for homeowners. Water conservation also directly benefits homeowners with onsite systems. Simply by reducing water use, homeowners can extend the life of their systems for many years, prevent system failures, and minimize maintenance costs, potentially saving hundreds of dollars.
There are additional benefits such as lower monthly water bills, reduced amount of money that homeowners and communities spend for wastewater treatment, an increased efficiency of wastewater treatment plant, and savings on energy costs.
Nonresidential wastewater in small communities is generated by diverse sources such as offices, businesses, supermarkets, restaurants, schools, hospitals, farms, manufacturers and other commercial, industrial, and institutional entities. Storm-water is a nonresidential source and carries trash and other pollutants from streets, as well as pesticides and fertilizers from yards and fields.
Because of the different characteristics of nonresidential wastewater, communities need to assess each source individually or compare similar types of nonresidential sources to ensure that adequate treatment is provided.
What is wastewater?
The potable water becomes wastewater after it gets contaminated with natural or synthetic microbiological compounds that arise out of human activities, commercial and industrial sources. They may be accompanied with surface water, ground water and storm water. Wastewater is sewage, storm-water and water that has been used for various purposes around the community. Unless properly treated, wastewater can harm public health and the environment.
Most communities generate wastewater from both residential and non-residential sources.
Residential Wastewater or Household Wastewater
Residential wastewater is a combination of excreta, flush water and all types of wastewater generated from every room in a house. It is more commonly known as sewage and is much diluted. There are two types of domestic sewage: black-water or wastewater from toilets, and gray water, which is wastewater from all sources except toilets. Black-water and gray-water have different characteristics, but both contain pollutants and disease causing agents. In the U.S, sewage varies regionally and from home to home. These are based on factors such as the number and type of water-using fixtures and appliances used at homes and even their habits, such as the types of food they eat.
Non-Residential Wastewater or Industrial Wastewater
This could be places such as industrial complexes, factories, offices, restaurants, farms and hospitals. Because of the different non-residential wastewater characteristics, communities need to assess each source individually to ensure that adequate treatment is provided. For example, laundries differ from many other industrial sources because they produce high volumes of wastewater containing lint fibers. Restaurants typically generate a lot of oil and grease. In addition, many industries produce wastewater high in chemical and biological pollutants that, can overburden onsite and community wastewater treatment systems.
Storm-water is a nonresidential source and carries trash and other pollutants from streets, as well as pesticides and fertilizers from yards and fields. Communities may require these types of nonresidential sources to provide preliminary treatment to protect community systems and public health.
Vegetable Plants, animals and human beings are the sources for origination of natural or synthetic organic compounds. Human excreta, paper products, detergents, cosmetics, food, agricultural products, wastes from commercial activities and wastes from industrial sources are organic in origin and considerable in quantity.
Organic compounds generated from the above sources are a combination of carbon, hydrogen, oxygen, nitrogen, sulfur and other trace elements. Organic compounds such as proteins, carbohydrates, and fats are degradable by organisms, however they can cause pollution.
Large concentration of degradable organics in wastewater is dangerous to lakes, streams, and oceans, because organisms consume dissolved oxygen in water to break down the wastes. This can reduce or deplete the supply of oxygen in the water needed by aquatic life, resulting in fish kills, increasing the odors, and overall deterioration of water quality.
Some organic compounds are more stable than others and cannot be quickly broken down by organisms. This poses an additional challenge for treatment. This is true with many synthetic organic compounds developed for agriculture and industry. Some of the synthetic organic compounds that belong to pesticides, herbicides, dyes, pigments, fried oils, and fried meats are toxic to humans, fish, and aquatic plants and often are disposed off improperly in drains or carried in storm-water. In receiving water bodies, they kill or contaminate fish, making them unfit to eat. They also can reduce the efficiency of the processes in treatment.
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Important wastewater contaminants and quality factors:
The presence of contaminants (or pollutants) in wastewater leads to the reduction of water quality and consequently interferes with its reuse. Presence of these contaminants also prevents the direct disposal of wastewater into environment since it degrades the quality of water and soil.
The table below lists:
# The contaminant sources
# The type of wastewater
# The effect
Wastewater is categorized in terms of:
# Quality factors
# Quality parameters
# Tests
The physical parameters include:
# Temperature (which affects rates of chemical and biochemical reactions)
# Viscosity (and hence efficiency of sedimentation of settleable solids)
# Solubility of gases
# Odor
# Color
# Solids
The physical characteristics help assessing the condition of domestic wastewater, whether fresh or septic and its earlier incarnations, for example ground water and/or industrial
wastewaters mixed with domestic wastewater.
The chemical quality of wastewater can be determined by studying the following:
# pH
# Alkalinity
# Chlorides
# Various forms of nitrogen
# Phosphorous
# Sulfur
# Heavy metals
# Toxic substances
# Gases
Above all, tests like BOD, COD, and TOC (which are used to estimate the organic content either directly or indirectly as oxygen consumed by organic matter).
The BOD test, in spite of its limitation, which is large time requirement (5 days), is a universally used test as it measures the biodegradable fraction of organic matter, unlike any other test.
Strength:
The strength of wastewater depends mainly on the degree of dilution. The wastewater characteristics can vary widely with local conditions, hour of the day, day of the week, season, and types of sewers
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Volume of wastewater discharge:
Wastewater is a combination of excreta, flushing water and other gray-water or sullage and is much diluted depending on the per capita water uses. The personal water consumption alone is between 200 and 300 liters per day. When the industrial and energy production usage is added to the equation, fresh water usage exceeds 5,000 liters per day on a per capita basis.
The volume of wastewater discharge can be reduced substantially through conservation of water. This is a good idea for a number of reasons:
# It lowers monthly water bills
# It can also reduce the money that homeowners and communities spend for wastewater treatment.
# Increased efficiency of wastewater treatment plant and savings on energy costs.
# Significant reduction in wastewater flows also can save on personnel costs, such as overtime, and can eliminate or
postpone the need to upgrade or expand facilities. It lowers sewer charges and taxes for homeowners. Water conservation also directly benefits homeowners with onsite systems. Simply by reducing water use, homeowners can extend the life of their systems for many years, prevent system failures, and minimize maintenance costs, potentially saving hundreds of dollars.
# Water conservation also indirectly helps in maintaining the water quality. Excessive water drawing (exceeding the water holding capacity of the soil) from ground sources allows ground water contamination from neighboring areas or sea. So, avoid unnecessary water drawing from ground sources.
[This blog has a Help Desk. Please post your queries there, with your Contact details if you want to be contacted. If your query is simple enough, I’ll try and answer back thru Help Desk. If it can only be answered by a specialist, I’ll try to identify a Subject Matter Expert (SME) in the relevant realm, and get him/ her to reply, thru this Help Desk or thru email. If your query is consultative in nature, she/ he may expect a fee, though.]
When water becomes wastewater:
The potable water becomes wastewater after it gets contaminated with natural or synthetic microbiological compounds that arises out of human activities, commercial and industrial sources. They may be accompanied with surface water, ground water and storm water. Wastewater is sewage, storm-water and water that have been used for various purposes around the community. Unless properly treated, wastewater can harm public health and the environment. Most communities generate wastewater from both residential and nonresidential sources.
Residential wastewater:
Although the word sewage usually brings toilets to mind, it is actually used to describe all types of wastewater generated from every room in a house. In the U.S, sewage varies regionally and from home to home. They are based on factors such as the number and type of water-using fixtures and appliances, the number of occupants, their ages, and even their habits, such as the types of food they eat. However, when compared to the variety of wastewater flows generated by different nonresidential sources, household wastewater shares many similar characteristics overall. There are two types of domestic sewage: black-water or wastewater from toilets, and gray water, which is wastewater from all sources except toilets. Black-water and gray-water have different characteristics, but both contain pollutants and disease causing agents that require treatment.
Nonresidential wastewater:
Nonresidential wastewater in small communities is generated by diverse sources like offices, businesses, Super markets, restaurants, schools, hospitals, farms, manufacturers, and other commercial, industrial, and institutional entities. Storm-water is a nonresidential source and carries trash and other pollutants from streets, as well as pesticides and fertilizers from yards and fields.
Because of the different nonresidential wastewater characteristics, communities need to assess each source individually or compare similar types of nonresidential sources to ensure that adequate treatment is provided. For example, public restrooms may generate wastewater with some characteristics similar to sewage, but usually at higher volumes and at different peak hours. The volume and pattern of wastewater flows from rental properties, hotels, and recreation areas often vary seasonally as well.
Laundries differ from many other nonresidential sources because they produce high volumes of wastewater containing lint fibers. Restaurants typically generate a lot of oil and grease. It may be necessary to provide pretreatment of oil and grease from restaurants or to collect it prior to treatment. For example, by adding grease traps to septic tanks.
Wastewater from some nonresidential sources also may require additional treatment. For example, storm-water should be collected separately to prevent the flooding of treatment plants during wet weather. Screens often remove trash and other large solids from storm sewers. In addition, many industries produce wastewater high in chemical and biological pollutants that, can overburden onsite and community systems. Dairy farms and breweries are good examples. Communities may require these types of nonresidential sources to provide their own treatment or preliminary treatment to protect community systems and public health.
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The viruses of greatest significance in the water borne transmission of infectious diseases are essentially those that multiply in the intestine of humans and are excreted in large numbers in the feces of infected individuals.
Although viruses cannot multiply outside the tissues of infected hosts, some enteric viruses appear to have a considerable ability to survive in the environment and remain infective.
Discharges of sewage and human excreta constitute the main source of human enteric viruses in the aquatic environment. With the various analytical methods currently available, wide variations are found in the numbers of viruses present in sewage.
The numbers of viruses and the species distribution will reflect the extent to which the population is carrying them. It may reduce the number of viruses by the population.
Sewage treatment may reduce the number of viruses 10-1000-fold, depending on the nature and extent of the treatment given. However, it will not eliminate them entirely, and the sludge produced during sewage treatment will often contain large numbers. As sewage mixes with receiving water, viruses are carried downstream. They remain detectable for varying periods of time, depending on the temperature, the degree to which they are absorbed onto sediments, the depth to which sunlight penetrates into the water, and other factors. Consequently, enteric viruses can be found in sewage polluted water at the intakes to water-treatment plants.
The relationship between the occurrence of viruses in water and risks to health is not a simple one. Viruses are replicating infectious agents that are among the smallest of all microorganisms. In essence, they are nucleic acid molecules that can enter cells and replicate in them, and code for proteins. They are capable of forming protective shells around them. Viruses pathogenic to humans can occur in polluted water. Some of the diseases attributed to them are listed below:
The nature of viruses:
| Virus Family | Members | No.of serotypes | Diseases caused |
|---|---|---|---|
| Picorna-viridae | Human polioviruses | 3 | Paralysis, meningitis, fever |
| Human echoviruses | 32 | Meningitis, respiratory disease, rash, fever, gastroenteritis | |
| Human coxsackie Viruses a1-22,24 | 23 | Enteroviral vesicular pharyngitis, respiratory disease, meningitis, enteroviral vesicular stomatitis with exanthem (hand, foot and mouth disease) | |
| Human coxsackile viruses b1-6 | 6 | Myocarditis, congenital heart anomalies, rash, fever, meningitis, respiratory disease, epidemic myalgia (pleurodynia) | |
| Human enteroviruses 68-71 | 4 | Meningitis, encephalitis, respiratory disease, rash, acute enteroviral haemorrhagic conjunctivitis, fever | |
| Hepatitis A virus | 1 | Hepatitis A | |
| Reo-viridae | Human reoviruses | 3 | Unknown |
| Human rotaviruses | 5 | Gastroenteritis, diarrhea | |
| Adeno-viridae | Human adenoviruses | 41 | Respiratory disease, conjunctivitis, gastroenteritis |
| Parvo-viridae | Adeno-associated viruses | 4 | Latent infection following integration of DNA into the cellular genome |
| Calici-viridae | Human caliciviruses | 5 | Gastroenteritis in infants and young children. |
| Small round structured viruses (including norwalk virus) | 14 | Gastroenteritis, acute viral gastroenteropathy (winter vomiting disease) | |
| Hepatitis E virus | Hepatitis E | ||
| Unknown | Astroviruses | 1 | Gastroenteritis, neonatal necrotizing enterocolitis |
| Papova-viridae | Papillomaviruses | 2 | Planter warts |
| Pathogen | Disease |
|---|---|
| Bacteria campylobacter jejuni | Gastroenteritis |
| Enteropathogenic escherichia coli | Gastroenteritis |
| Legionella pneumophila | Acute respiratory illness |
| Salmonella | Typhoid, paratyphoid, salmonellosis |
| Shigella | Becillary dysentery |
| Vibrio cholerae | Gastroenteritis |
| Protozoa cryptosporidium | Diarrhea |
| Entamoeba histolytica | Amoebic dysentery |
| Giardia lamblia | Diarrhea |
| Naegleriafowleri | Meningoencephalitis |
| Enteroviruses | Respiratory illness |
| Enteroviruses | Eye infection |
| Adenovirus | Gastroenteritis |
| Astrovirus | Gastroenteritis |
| Calicivirus | Gastroenteritis |
| Coxsackievirus A | Myocarditis, meningitis, respiratory illness |
| Echovirus | Meningitis, diarrhea, fever, respiratory illness |
| Hepatitis A virus | Infectious hepatitis |
| Norwalk virus | Diarrhea, vomiting, fever |
| Poliovirus | Meningitis, paralysis |
| Rotavirus | Diarrhea, vomiting |
Recognition of seawater in ground water:Ground water samples taken from where there is seawater intrusion may have a chemical composition different from a simple proportional mixing of seawater and ground water. The popular belief is that, increase of total dissolved solids or chlorides alone is a valuable parameter to determine the extent of intrusion. However, the chloride-bicarbonate ratio (ratio of chlorides to the sum of carbonates and bicarbonates) is more important, which is definitely a pointer to the intrusion as given below:
| Type of water | Cl/CO3 + HCO3 |
|---|---|
| Normal good ground water in aquifer | 1 |
| Slightly contaminated ground water | 1 to 2 |
| Moderately contaminated ground water | 2 to 5 |
| Injuriously contaminated ground water | 5 to 10 |
| Highly contaminated ground water (near sea shore) | 10 to 20 |
| Sea water | 200 |
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