Nowadays, it is not surprising to find dirty water all over the world as lots of activities are done with the use of water and they may include;
- Domestication for example; laundry, cooking, drinking, bathing and so on.
- Industrialization for example; washing of machines, manufacture of certain products as well as powering up the machines.
- Surface runoff
- Sewer infiltration
This dirty water is what we called Waste water, which is any water whose quality is dramatically been affected by anthropogenic materials or influences. By illustration, a certain type of waste water called sewage which is composing of domestic waste is contaminated with lots of feces and urine from human toilets. By not letting you to the wrong point, sewage in a general sense refers to any type of waste water.
Waste water is said to originate from different activities and processes. Some of such activities and processes from which waste water may originate may include:
- Feces and Urine also called Human Excreta. The waste water from here is also called black water and originates from feces and wiped used by humans and is usually collected through flushed toilets.
- Waste water from laundry or washing water. This originates from water used for washing of cars, ditches, floors, dresses and so on and is also called grey water.
- Drainage waste water from storms;
- Drainage from highways which may include oil, residues from rubber;
- Waste originating from agricultural activities for example irrigation;
- Hydraulically fractured waste sources;
- Waste water from the production of oil and natural gas.
Components in waste water
Just like any other substance in the real world, it should not be surprising that waste water is composed of component substances as well as some elements. Some of these constituents may include the following;
- Non pathogenic bacteria;
- Organic materials or particles such as feces, plant materials, papers, hair, food, vomit;
- Organic materials which are soluble such as urea and fruit sugars;
- Toxins such as pesticides and herbicides;
- Animals such as small fishes, protozoa, insects;
- Inorganic materials such as ceramics, sand;
- Gases like carbon dioxide, methane and so on.
With emergence in development and technology, there are many methods being implemented to manage waste water before it is being disposed. But with some areas still being under developed, there is still little or no waste water management schemes yet being implemented must especially in rural areas and hence giving access to natural means of disposing waste water as discuss below.
- In some areas notably urban environments, runoff from streets is usually carried in storm drain while waste water from municipalities is usually carried in sanitary sewers. This is usually done with access to a manhole. With increasing duration of precipitation, sewer over flow may occur and by so doing, causing untreated sewage to flow back into the environment which in turn threatens human life and the environment in general.
- Sewage is usually also disposed of by directly draining it to some watersheds with little or no treatment and hence turn threatens human life and the environment in general.
- At lower concentrations, bioaccumulation of chemicals in animals and plants can still cause serious health problems to mankind. Pathogens ( causative agents of infections) are a major cause of diseases in humans.
Waste Water Treatment
Waste water must be treated as soon as it is being released into the environment, so as to prevent its negative effects to the environment as well as the health of the general public. In both urban and rural areas, the manner or techniques in which waste water is treated is not the same. Urban areas require a lot of planning and management on how to treat their waste water as a result of the large population and the high number of activities carried out in towns than in rural areas. This therefore means that the standards as well as the minimum effluent level required when treating and discharging waste water in urban areas is not the same as in rural areas.
With less concern in most countries for rural areas, even though some implement the same techniques used in urban waste water treatment, yet they are still poorly implemented and or managed creating difficult situations in rural areas.
The real thing is most people do not know what waste water treatment is all about and so it does not matter to them disposing untreated water or even reused in agriculture.
Waste water treatment is a process of converting waste water into an effluent that can be returned to the global water cycle (which is usually also called the Hydrological cycle) with little environmental constraints or reused. Removing impurities from treated water is called treatment. With increase in development, a physical infrastructure called the waste water treatment plant has been developed. It is important to note that there are many such plants some of which include;
- Sewage treatment plant
- Agricultural treatment plant
- Industrial waste water treatment plant
- Leachate treatment plant.
Waste water treatment processes
There are many processes used in treating waste water depending on the extend and type of contamination
- Phase separation
- Biochemical Oxidation
- Chemical oxidation
Treated waste water can still be reused for certain instances as well as for some activities which may include;
- For drinking
- In industries for example cooling of towers
- Artificial recharge of aquifers
- Rehabilitation of natural ecosystem
One of the most important areas where waste water is reused is in agriculture and gardening due to some beneficial factors which will be discussed below.
Reuse of treated waste water in agriculture and gardening.
The advantages of using recycled water in agricultural activities and or irrigation may be as follows below;
- The low cost of supply compared to some other sources
- Consistently supplied irrespective of season, associated water restriction and climate condition.
- It also serves as a fertilizer in irrigation in case where it contains nutrients such as phosphorus, nitrogen and potassium.
In most cases, waste water is used in irrigation untreated most especially in low income countries like in the developing world. This in turn causes environmental pollution hence threatening the health of people.
This therefore means that such practices should be avoided. In order to tackle this practice, some organizations have been created. Some of which are include the United Nations Environmental Program (UNEP) and the Food and Agriculture organization of the United Nations (FAO) each with its specific functions.