Getting familiarized with basic water treatment technologies_Session4

After  Primary stages  in  Water Treatment  we enetr the secondary stage  

Secondary stage involves treatment with activated carbon.Normaly treatment is done when water is passed through an activated carbon bed in a vertical pressurised vessel.

What is  acivated carbon? 

There are  granular activated carbon (GAC) and powdered activated carbon (PAC) .

Activated carbon is carbon that has been exposed to very high temperature, creating a vast network of pores with a very large internal surface area; one gram of activated carbon has a surface area equivalent to that of a football field.

Why Activated Carbon is   considered  crucial  in water treatment?

 Activated Carbon removes contaminants through adsorption, a process in which dissolved contaminants adhere to the surface of the carbon particle. Activate Carbon removes  organic contaminants such as volatile organic chemicals( VOCs), solvents, toxic compounds like poly chlorinated biphenyls(PCBs), herbicides and pesticides.

 Down below is a Diagonal View of an Activated Carbon Filter

 

After a period of a few months or years, depending on the concentration of the contaminants, the surface of the pores in the GAC can no longer adsorb contaminants and the carbon must be replaced

And we , at Trueline Water Technonolgies, install and maintain 

state of the art  Activated Carbon Filter.

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Our Next session is  about,IRFs , Iron Removal Filters.

 No water is safe to drink unless the Waterborne Pathogens are removed.

What does it mean by Wateborne Pathogens?

 Bacteria, viruses and protozoan that cause disease are known as pathogens.

How pathogens occur in water?

Pathogens may get into water and spread when infected humans or animals pass the bacteria, viruses and protozoa in their fecal waste. Human or animal wastes in watersheds, failing septic systems, failing sewage treatment plants or cross-connections of water lines with sewage lines provide the potential for contaminating water with pathogens

    The water may not appear to be contaminated and may even look crystal clear, because feces has been broken up, dispersed and diluted into microscopic particles. These particles, containing pathogens, may remain in the water and be passed to humans or animals unless adequately treated

Detection of Pathogens

Total Coliforms (including fecal coliform and E. Coli)  count is used as an indicator that other potentially harmful bacteria may be present.As the source of contaminant is human and animal fecal waste, the maximum contaminant level (MCL) is set as  zero in drinking water. MCLs are enforcable standards in public water system.

Waterborne Diseases 

Most pathogens are generally associated with diseases that cause intestinal illness and affect people in a relatively short amount of time, generally a few days to two weeks. They can cause illness through exposure to small quantities of contaminated water or food or from direct contact with infected people or animals.  For another person to become infected, he or she must take that pathogen in through the mouth, And that happens when drinking water is contaminated.

 Bacteria-Caused Diseases ;

 Campylobacteriosis is the most common diarrhea illness caused by bacteria. Other symptoms include abdominal pain, malaise, fever, nausea and vomiting. Symptoms begin three to five days after exposure. The illness is frequently over within two to five days and usually lasts no more than 10 days

    Viral-Caused Diseases ;

The onset is usually abrupt with fever, malaise, loss of appetite, nausea and abdominal discomfort, followed within a few days by jaundice. The disease varies in severity from a mild illness lasting one to two weeks, to a severely disabling disease lasting several months (rare)

Protozoan Caused Diseases 

 Protozoan pathogens are larger than bacteria and viruses but still microscopic. They invade and inhabit the gastrointestinal tract. Some parasites enter the environment in a dormant form, with a protective cell wall, called a “cyst.” 

 Disinfection

All bacteria in water are readily killed or inactivated with chlorine or other disinfectants. 

 Most viruses in drinking water can be inactivated by chlorine or other disinfectants and some strains need advanced treatments like ozonozation .

The cyst can survive in the environment for long periods of time and be extremely resistant to conventional disinfectants such as chlorine. Effective filtration treatment is therefore critical to removing these organisms from water sources.  

Disinfection by Chlorine

Chlorine is one of the most versatile chemicals used in water treatment/ disinfection.Chorine can be applied for the deactivation of most microorganisms and is relatively cheap.The chlorine attacks bacterial cells and protien coat of viruses, hence effectievel y killing both bacteria and viruses.

There are certain factors to be considered in chlorination process;

Chlorine Concentration.Contact time,pH interfering substances

And we , at Trueline Water Technonolgies,  design, erect and commission a complete  chlorine dosing system

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Down below is the picture of  a typical Chlorine Dosing Pump 

 The concept of slow sand filter

 is that of natural filtration occuring in nature.

And What is natural Filtration?

 The water emerging from  deep in the ground  may have fallen as rain many tens, hundreds, or thousands of years ago. Soil and rock layers naturally filter the ground water to a high degree of clarity/ Often it does not require additional treatment.

What's a Slow Sand Filter? And how to create one?S

Slow sand filters, due to their simple design, may be created as DIY,  Do It Yourself project.

Slow Sand Filters are Typicaliy 1-2 metere deep  Rectangular or Cylindrical tank with a loading rate of 200 to 400 litre/hr /m2 .Slow sand filters differ from all other filters used to treat drinking water in that they work by using a complex biological film that grows naturally on the surface of the sand. The sand itself does not perform any filtration function but simply acts as a substrate, that is providing  an underlying layer for micro organisms to grow and  form a bilogical film .So  slow sand filters use biological processes to clean the water. And these are are non-pressurized systems. Slow sand filters do not require chemicals or electricity to operate.

  Cleaning , which is equivalent to back washing in pressure filters, is traditionally done by use of a mechanical scraper, which is usually driven into the filter bed once the bed has been dried out.

  Slow sand filters are recognized by the World Health Organization,as being superior technology for the treatment of surface water sources. According to the World Health Organization, "Under suitable circumstances, slow sand filtration may be not only the cheapest and simplest but also the most efficient method of water treatment."

                                 Typical Configuration of a slow sand filtration system

And due to slow filtration rate ,Slow sand filters require more land space.

And we , at Trueline Water Technonolgies, help you create onein our compound.Connect to us at Web;http;//truelinewatertechnologies.business.site/ 

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And know that Disinfection is generally  carried out along with primary filtration , which we were discussing in last two sessions.So our next session is Disinfection of Drinking Water.

 

Why it is necessary to purify the water ? 

Well, for starters, it helps to know that Water is a universal solvent. Anything and everything in the planet earth dissolves in it, though in varying degrees.And water body is a breeding ground  for  any number of micro organisms ,pathogenic or not.     

Considering these basic facts its literally dangerous to consume water as such.

And how do you purify water? 

Process  of Purification start with identifying source of water.

To start with we are considering normal well water.

 Know that Purification involves mechanical as well as chemical methods. We often use the term water treatment for purification process.

Let's begin with Filtration.There are  3 categories , each involves several modes, in Water Filtration

Primary Filtration.

Secondary Filtration 

Tertiary or Adavanced Filtration

Let's discuss the process involved in the Primary Filtration , where domestic water supply is involved;

Primary Filtration, through Pressure Sand Filter

   The raw water is collected in the collection tank which also acts as a pre-sedimentation basin. Pre-sedimentation allows the suspended  particles to settle down increasing the efficiency of the filtration  process, Water is drawn from the settling tank through feed pump and subjected to primary filtration through a Pressure Sand Filter. In Sand filter ,media is enclosed in a vessel and water is forced through it under pressure, The unit filters out particles  larger than their specified pore sizes. The pore size between sand particles are 20 to 40 microns, one micron bieng 1/100th of a mili mtetr.Primary filtration removes turbidity, odour , colour and taste.This sort of Filtration is also called "deep bed Filtration"

A schematic diagram of sand filtration

 And down below is  the picture of an actual sand filtration unit

What you see in the picture is the Sand Filtration part of a  Water Treatment plant,,Designed, Supplied &  Commissioned by us, Trueline Water Technologies, in an apartment complex, in Aluva..

And in the next session  we will discuss another mode of Primary Filtraion, called Slow Filtration.

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