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.
[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.]
The toxicity of municipal effluents depends on a variety of factors, including the size and characteristics of the sewer-shed, the type and efficiency of treatment and disinfection processes and the physical, chemical and biological characteristics of the receiving waters.
In many cases, the acute toxicity of municipal wastewater effluents is due to unionized ammonia, in the case of chlorinated effluents, it is because of total residual chlorine that can make wastewater toxic. Other causes of wastewater contamination including cyanide, sulfides, phenols, surfactants and heavy metals, such as copper, zinc and chromium, also contribute to acute or chronic toxicity.
Many factors including pH, hardness, dissolved organic carbon and temperature can moderate the toxicity in the water treatment plant effluent or receiving environment. Despite considerable investment in treatment systems, acute and chronic toxicity remains a concern in many sites receiving municipal effluents as well as toxic sewage.
Many chemicals detected in municipal effluents are hydrophobic and may tend to adsorb to particles in the effluent or sediments in the receiving environment, than remain in the water phase. The distribution of these chemicals may therefore differ considerably from more soluble compounds, which will tend to move with the effluent plume.
Hydrophobic wastewater toxic chemicals may also tend to bio-accumulate in organisms and move through food webs. The distribution and fate of contaminants in the environment is extremely complex. It is dependent on the physical and chemical characteristics of the chemicals as well as the physical, chemical and biological characteristics of the receiving environment.
Ammonia, chloramines, nonyl phenol and its ethoxylates and textile mill effluents are associated with municipal effluents and have been known to make wastewater toxic.
Various wastewater microorganism species have an adverse impact on human health. This article analyses what health risks we are exposed to, from some wastewater microorganism species.
Some illnesses from wastewater-related sources are relatively common. Gastroenteritis can result from a variety of wastewater microorganism; other important wastewater-related diseases include hepatitis A, typhoid, polio, cholera and dysentery. Outbreaks of these diseases can occur as a result of, drinking water from wells polluted by a combination of different wastewater microorganism species, eating contaminated fish, or indulging in recreational activities in polluted water bodies containing water borne pathogen. Animals and insects that come in contact with wastewater can spread some illnesses as well.
Even municipal drinking water sources are not completely immune to health risks from wastewater pathogens. Drinking water treatment efforts can become overwhelmed when water resources are heavily polluted by wastewater microorganism species.
Pathogenic viruses, bacteria, protozoa and helminthes and other wastewater microorganism species, may be present in raw municipal wastewater and will survive in the environment longer periods. Sewage pathogens will be present in wastewater at much lower levels than the coliform group of bacteria, which are much easier to identify and enumerate (as No. of Total Coliforms / 100ml). Escherichia Coli are the most widely adopted indicator of fecal pollution and they can also be isolated and identified fairly simply, with their numbers usually being given in the form of fecal Coliforms (FC)/100 ml of wastewater.
There are various kinds of enteric microorganisms present in human excreta and animal manure; some of these are pathogens and some are non-pathogens. Microorganisms in wastewater can be classified into such major groups as bacteria, viruses, protozoa, and helminthes. Some of the important enteric pathogens commonly found in human excreta and wastewater, diseases they cause, modes of transmission, and geographical distribution are shown below:
Pathogen: Vibrio Cholera; Disease: Cholera; Transmission: Person to person;
Pathogen: Salmonella Typhi; Disease: Typhoid fever; Transmission: Person (or animals) to person;
Pathogen: Other types of Salmonellae; Disease: Various enteric fevers (often called paratyphoid), gastroenteritis, septicemia, (generalized infection in which organisms multiply in the blood stream; Transmission: Person (or animals) to person;
Pathogen: Shigella Dysenteriae; Disease: Bacterial Dysentery; Transmission: Person to person
Pathogen: Escheiria Coli; Disease: Diarrhea; Transmission: Person to person
Pathogen: Poliovirus; Disease: Poliomycetes; Transmission: Person to person
Pathogen: Coxsackievirus; Disease: Various cases including respiratory disease, fevers, rashes, paralysis, aseptic meningitis, myocarditis; Transmission: Person to person
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.
A new technology in wastewater treatment, called Advanced Immobilized Cell Reactor technology (you can download a free comprehensive eBook on this here:
http://www.all-about-wastewater-treatment.com/AdvancedTreatment.php), available now, promises benefits like:
* Up to 25% lower plant cost
* Up to 50% lower operating costs
* Up to 50% lower maintenance costs
* Up to 90% less sludge production
* Up to 60% smaller footprint (can even be set up underground or on the roof)
* Speedy plant construction (2 to 6 weeks for small/medium sized plants)
* Insures high purity level of treated water, as below:
(i) BOD (Biological Oxygen Demand): less than 5 mg/Liter,
(ii) COD (Chemical Oxygen Demand): less than 60 mg/Liter (or even better)
* Meets EVA specifications of the US and UK
* Meets all input specifications of wastewater from large industries/ cities/ towns.
It has varied applications:
* Small sizes for both industrial and domestic applications.
* Can also be created in standard sized, skid-mounted form
* Can be readily installed cost effectively in small homes, individual/ small business establishments like car washes, bakeries, restaurants, mini-hotels, etc., and plants for rural areas.
* Can also be installed with Sludge-handling model or Sludge-absorption model for Domestic use
* Can be used to facilitate re-use of water for purposes like golf courses, toilets, gardening, and even washing.
* Or just let off the treated water to recharge the ground water.
What’s more, it is cost effective to implement small Plants using this technology anywhere in the world, with mostly indigenous material and conforming to local standards. This technology has been implemented successfully in many locations.
The Advanced ‘Immobilized Cell Reactor’ technology can also be applied to the treatment of domestic wastewater. The presence of organic, inorganic chemicals, and organisms, both pathogenic and non-pathogenic in nature, make domestic wastewater complex. Conventional biological treatment systems do not remove dissolved organics and microorganisms satisfactorily. Moreover, the systems are not efficient enough to recover the water for reuse purpose.
Integrated biological and chemical oxidation happens in a single reactor. The reactor consists of a tall column packed with activated carbon. The activated carbon is immobilized with chemo autotrophs. Oxygen required for the oxidation of organics in wastewater is supplied in the form of compressed air from the bottom of the reactor. The counter-current movement of the liquid and air streams enables the dissolved organics to undergo oxidation and desorb the converted products, so that the activated carbon maintains its activity throughout the operation. The domestic wastewater treated through Advanced ‘Immobilized Cell Reactor’ system has reduced BOD by 94%, COD by 90% and sulfide by 100%.
However, the technology also has some limitations:
* Permeability index is less than that of sand filters
* Maximum organic loading rate allowed is limited
* Performance is limited by the presence of suspended solids in wastewater.
* Anaerobic treatment is an essential unit of operation before proceeding to Advanced ‘Immobilized Cell Reactor’ reactor to reduce the viscosity of wastewater and eliminate colloidal solids.
* Multiple modules are required to handle huge volumes instead of a single module.
All in all, the Advanced ‘Immobilized Cell Reactor’ technology can be applied across a wide spectrum of industries. It has performed at a credible level for the removal of organics estimated as BOD and COD from wastewater generated in leather garment manufacturing, textile-yarn-dyeing , sago, chemical, and pharmaceutical industries.
You can download a free comprehensive eBook on this here:
http://www.all-about-wastewater-treatment.com/AdvancedTreatment.php
For Commercial Inquiries (Plant Purchase, Installation, Commissioning & Maintenance, OR for Technology Licensing, or for professional advice/ consultancy from the authors of the eBook), please post your Inquiry at the Help Desk. We will get the author to respond to you. This service is offered on a ‘FREE of cost’, ‘non-obligatory’ basis.
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.
[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.]
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
[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.]
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