Water Treatment Journal

Softener design for hard water

2011-08-25T11:29:00.000+05:30

Softener Operation

Thumb rules of designing a Softener

Step 1 – To Select resin quantity (ltrs) for a particular hardness (ppm) for a particular output (m3) per regeneration per hour based on regeneration level 160 gm/ltr, ion exchange capacity = 55, TDS limit = 1500 ppm

Resin Quty. = Load (ppm as CaCO3) * Flow * time

Ex. Capacity

For example

Load = Hardness = 100 ppm as CaCO3

Flow = 5M3/hr

Time = (Service Cycle) = 12 hrs.

Ex. Capacity =60 gm as CaCO3

Resin Quanitity = 100 * 5 * 12

= 100 litres

Note :

Na/Tc and TDS and correction factor should be applied.
Actual Resin Quantity = 60* correction due Na/Tc factor * Correction due to TH factor = 60 * 0.96 * 0.97 = 56 (approximately)

Hence Ion Exchange load for designing a softener is 56. These calculations are based on Ion Exchange resin and will varry from manufacturer to manufacturer resin.

Step 2 – To select vessel model for a selected resin quantity, approx. flow rates based on linear velocity min = 8 m3/m2/hr and max = 25 m3/m2/hr, and freeboard 5-100 %,

Important points on Softener

· Linear velocity should not be less than 8m3/m2/hr and should not be more than 25m3/m2/hr.

· Regeneration level, hardness leakage desired and correction factors can be found from resin supplier graph Tables.

Ion Exchange Materials: Properties and Applications

Ultraviolet Dosage Requirements in water and wastewater treatment

2011-08-25T10:59:00.001+05:30

Ultraviolet Dose Requirements

The energy required to inactivate a microorganism is termed the UV dose or UV fluence and is measured in mJ.cm-2, or mW.s.cm-2, or J.m-2. UV fluence is the modern term, used to represent UV light impacting on a small parcel of fluid from all directions. UV light is scattered by particulate and colloidal material, meaning that it does not merely radiate outwards from the lamp. Light is scattered in all directions, including forward- and back-scattered.

1 mJ.cm-2 = 1000 mW.s.cm-2 = 10 J.m-2

This is defined as being the amount of UV energy reaching the organism (the intensity) multiplied by the contact time (the time the microorganism is in the UV irradiation field).

Dose = Average intensity (eg. mW.cm-2) x contact time (eg. seconds)

Severin (Severin, 1983) investigated the temperature dependence of some bacteria and viruses. Between the temperatures of 5 and 35 ºC. He noted that the inactivation rate increased by less than 20% for f2 bacteriophage, for the above increase in temperature and increased by less than 10% for E. coli and Candida parapsilosis(Is the conclusion correct?). Malley (Malley) (Can someone insert the reference. UVDGM ref is incorrect. Is the conclusion correct?) found that MS2 phage inactivation was temperature independent.

Malley (Malley) (Can someone insert the reference. UVDGM ref is incorrect) found that inactivation is independent of pH, between pH 6 and 9.

Sommer (Sommer, 1999) investigated the reciprocity of time and intensity for E.coli strains, Bacillus subtillis and coliphages. Tests revealed higher inactivation at the higher UV intensities and the same dose, for E. coli. Reciprocity differences for other microorganisms were not statistically significant. It is hypothesized that the difference for E. coli was due to repair mechanisms taking place in the low intensity case. Others (Oliver, 1975) (Rice, 2001) investigating reciprocity over a range of intensity of 1 to 200 mW/cm2 found no difference in inactivation rates

Ultraviolet Light in Water and Wastewater Sanitation

Coagulation and Flocculation in Water and Wastewater Treatment

2011-08-25T10:33:00.000+05:30

Coagulation and Flocculation

Coagulation and flocculation are an essential part of drinking water treatment as well as wastewater treatment.This article provides an overview of the processes and looks at the latest thinking.Coagulation and flocculation are essential processes in various disciplines. In potable water treatment, clarification of water using coagulating agents has been practiced from ancient times. As early as 2000 BC the Egyptians used almonds smeared around vessels to clarify river water. The use of alum as a coagulant by the Romans was mentioned in around 77 AD. By 1757, alum was being used for coagulation in municipal water treatment in England.
Coagulation is also important in several wastewater treatment operations. A common example is chemical phosphorus removal and another, in overloaded wastewater treatment plants, is the practice of chemically enhancing primary treatment to reduce suspended solids and organic loads from primary clarifiers.
The Coagulants
The commonly used metal coagulants fall into two general categories: those based on aluminum and those based on iron. The aluminum coagulants include aluminum sulfate, aluminum chloride and sodium aluminate. The iron coagulants include ferric sulfate, ferrous sulfate, ferric chloride and ferric chloride sulfate. Other chemicals used as coagulants include hydrated lime and magnesium carbonate.
The effectiveness of aluminum and iron coagulants arises principally from their ability to form multi-charged polynuclear complexes with enhanced adsorption characteristics. The nature of the complexes formed may be controlled by the pH of the system.
When metal coagulants are added to water the metal ions (Al and Fe) hydrolyze rapidly but in a somewhat uncontrolled manner, forming a series of metal hydrolysis species. The efficiency of rapid mixing, the pH, and the coagulant dosage determine which hydrolysis species is effective for treatment.
There has been considerable development of pre-hydrolyzed inorganic coagulants, based on both aluminum and iron to produce the correct hydrolysis species regardless of the process conditions during treatment. These include aluminum chlorohydrate, polyaluminum chloride, polyaluminum sulfate chloride, polyaluminum silicate chloride and forms of polyaluminum chloride with organic polymers. Iron forms include polyferric sulfate and ferric salts with polymers. There are also polymerized aluminum-iron blends.
The principal advantages of pre-polymerized inorganic coagulants are that they are able to function efficiently over wide ranges of pH and raw water temperatures. They are less sensitive to low water temperatures; lower dosages are required to achieve water treatment goals; less chemical residuals are produced; and lower chloride or sulfate residuals are produced, resulting in lower final water TDS. They also produce lower metal residuals.
Pre-polymerized inorganic coagulants are prepared with varying basicity ratios, base concentrations, base addition rates, initial metal concentrations, ageing time, and ageing temperature. Because of the highly specific nature of these products, the best formulation for a particular water is case specific, and needs to be determined by jar testing. For example, in some applications alum may outperform some of the polyaluminum chloride formulations1.
PoIymers are a large range of natural or synthetic, water soluble, macromolecular compounds that have the ability to destabilize or enhance flocculation of the constituents of a body of water.
Natural polymers have long been used as flocculants. For example, Sanskrit literature from around 2000 BC mentions the use of crushed nuts from the Nirmali tree (Strychnos potatorum) for clarifying water – a practice still alive today in parts of Tamil Nadu in Inia, where the plant is known as Therran and cultivated also for its medicinal properties. In general, the advantages of natural polymers are that they are virtually free of toxins, biodegradable in the environment and the raw products are often locally available. However, the use of synthetic polymers is more widespread. They are, in general, more effective as flocculants because of the level of control made possible during manufacture.
Important mechanisms relating to polymers during treatment include electrostatic and bridging effects. Polymers are available in various forms including solutions, powders or beads, oil or water-based emulsions, and the Mannich types. The polymer charge density influences the configuration in solution: for a given molecular weight, increasing charge density stretches the polymer chains through increasing electrostatic repulsion between charged units, thereby increasing the viscosity of the polymer solution.
One concern with synthetic polymers relates to potential toxicity issues, generally arising from residual unreacted monomers. However, the proportion of unreacted monomers can be controlled during manufacture, and the quantities present in treated waters are generally low.
Removal of Natural Organic Matter
Natural organic material (NOM) is usually associated with humic substances arising from the aqueous extraction of living woody substances, the solution of degradation products in decaying wood and the solution of soil organic matter. These substances are objectionable for a number of reasons: they tend to impart color to waters; they act as a vehicle for transporting toxic substances and micro-pollutants, including heavy metals and organic pollutants; and they react with chlorine to form potentially carcinogenic by-products.
The degree to which coagulation can remove organic material depends on the type of material present.
Flocs in Water Treatment

Ionized water

2011-08-09T09:55:00.000+05:30

The basics of pH / ORP alteration in ionized water
Ionization alters water in two significant and measurable ways: pH and ORP. These alterations to water are what make it very different from other waters you may drink.
pH
pH stands for "potential hydrogen" and is a measurement that provides an indication of the level of hydrogen in a substance. It is measured by the pH scale. Proper body pH is an Important factor in good health.
ORP
The other way an ionizer alters the water is in ORP. This stands for Oxidation Reduction Potential. Most leading water researchers agree that in ionized water the elevated pH is good, but that ORP is more important. Alteration to the ORP is what causes the microclustering, antioxidant and oxygenating effects.

ORP is a potential energy that is stored and ready to be put to work. It's not necessarily working, but we know that the energy is there and we can measure it.

In electrical terms, potential energy can be measured. When we use the term potential in describing ORP, we are actually talking about electrical potential as expressed in millivolts. This potential is measured in water with an ORP meter. What you measure is the very slight voltage in water. We are actually measuring the presence of oxidizing or reducing agents by their specific electrical charge, thus Oxidation Reduction "Potential". High pH water has More "reducing" agents (-ORP) and low pH water has more oxidizing agents (+ORP).

Oxidation is what turns an apple brown after it is cut or causes metal to rust. Rust weakens metal and signifies the deterioration of the apple. The process of oxidation steals electrons from the surface being oxidized. When we measure a something’s oxidizing potential, it is expressed in +ORP and measures the concentration of ions or oxidizing agents.

A reducing agent is simply something that inhibits or slows the process of oxidation. The reducing agent does this by donating an electron. When we measure a solution's oxidation reduction potential, it is expressed in terms of ORP and measures the concentration of ions or reducing agents.

pH and ORP alteration is a highly variable and depends primarily on three factors:

1. The source water and its natural mineral content – water varies widely in this respect
2. The voltage applied to the water during electrolysis
3. The flow rate through the ionizer’s water cell

An ionizer works primarily on the mineral content in the water.

The Miraculous Properties of Ionized Water - The Definitive Guide to the World's Healthiest Substance

SWIMMING POOL pH CORRECTION

2011-08-08T17:26:00.001+05:30

pH CORRECTION
All chlorine based sanitisers become less effective at killing bacteria and viruses as pH rises ( Become more alkaline)
To keep the chlorine working it is recommended that pH is kept below 7.6. However if pool water becomes less alkaline it also gets corrosive and less comfortable to swim in. Also if pH drops below 7.2 it will start to attack some liners. Therefore the pH is recommended to be above 7.2. So the normal range that a pool water should be kept at 7.2 to 7.6 (Ideally7.4 to 7.6 ). On most pools the pH will tend to rise so pH reducing chemicals like sodium bisulphate is added .
swimming pool pH

Chlorine in swimming pool

2011-08-07T22:36:00.000+05:30

Chlorine Remover
Sometimes too much chlorine gets into the pool , often by accidentally overdosing the chlorine or after shock dosing to get ride of algae. It is not recommended to swim in water with more than 3 mg/l of chlorine. Chlorine remover ( Sodium thiosulphate) will remove that chlorine so you can swim straight away . Be careful not overdose chlorine remover or you will have to add lots of chlorine to chlorine remover. That is good for chemical suppliers profits not for your pockets.
First carefully test the pool water to get an accurate chlorine level. The dosage of chlorine remover will be in the label. or we can find it out by taking a sample of 10 litters of pool water in a plastic bucket and doze the sodium thiosalphate. dosage must start from .25 mg/l and find out the chlorine after 2 minutes. Then calculate it for the pool.
swimming pool

SWIMMING POOL BASICS

2011-08-05T20:24:00.000+05:30

What is a properly maintained pool ?.

A properly maintained pool is one that is visually and biologically clean.

How do I tell if my pool is biologically Clean ?.

By using a test kit , and measuring your pools chlorine,alkalinity and pH level. The test kit is easy to use and your pool equipment supplier will be able to tell you how to use it. If you maintain the proper chlorine and pH level, Bacteria and algae will be killed, and your pool will be biologically safe.

What is pH ?.

pH refers to the acidity/ basicity level of your pool water. The reason it's important is that unless is your pool is with in a certain pH range, your chlorine can't chemically interact with the bacteria and algae it's supposed to kill.

Most pool owners don't realize how important the pH level is . The proper range is 7.4 - 7.6

SWIMMING POOL TREATMENT

2011-08-04T10:22:00.001+05:30

The important points to remember about the swimming pool is the water analysis parameters. We have to keep the some water parameters for the safety and cleanses of the water. we can achieve this target by keeping
Free chlorine- 1 to 1.5ppm
pH - 7.4 to 7.6
Total Alkalinity - 120 to 160 ppm
Calcium hardness -(Tiled pools) - 200 ppm minimum
Calcium hardness - (Liner/ fiber glass pools) - 100 ppm minimum

These parameters will help you the clean and hygienic pool
Requirements For tiled pools
1) Stabilizes chlorine
2)Sodium bisulphate
3)Alkalinity Builder
4)Calcium Builder
5)Poly quat algaecide
6)Aluminium sulphate
7)Water Test Kit
Requirement for Liner/fiber glass pool
1) Stabilized chlorine
2)Sodium bisulphate
3)Alkalinity Builder
4)Poly quat algecide
5)Aluminium Sulphate
6)Water test kit
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Rainwater Harvesting With Silpaulin Sheet

2011-07-27T17:16:00.002+05:30

We can collect the rain water in Silpaulin sheet. The technology is very simple. This water we can use for our home, agriculture,Fish farm, Aquarium, Farm etc. This method is very useful for and proved.Quantity of water can be collected from the each place is based on the available rain in that area. Some organisations can make the artificial rain. First we have to make a pit by digging the land and covering the pit with a HDPE sheet.

Calculations
Assume that you are getting 300 mm of rain per year

That means you will get 3000 liters of water from one square meter area per year

Design for Water: Rainwater Harvesting, Stormwater Catchment, and Alternate Water Reuse

Rainwater Harvesting Minimum Requirements and Technology

2011-07-27T11:19:00.001+05:30

For Installing a rainwater system, Minimum requirement is 10 square meters of Roof area and 10 square meters of ground area.
Calculating the size of the Storage tank
The size of the tank is calculating based on the following assumption.

Per day one person required 5litters of water for Drinking and cooking . If you are the 5 member family you required 25 litters of water per day. If your summer is 100 days per year, you required 2500 litters of water per year.
Requirements for 5000 litters of Ferro-Cement tank and system
1) Chicken Mesh-12.12 mm 20 gauge - 1 role
2)12.12 mm GI wire mesh 16 gauge-5 nos
3) Cement- 9 bag ( 25 kgs)
4) Sand - As per requirements
5) Bricks-350 nos.
6)Gravel 6mm -2 bag
7)6 mm MS road- 10 kg
8) GI tag wire- 5 kg
9) Water proof-1 kg
10) 125 mm PVC Pipe- 5 meters
11)12:152 mm GI Nipple 1 nos
12 ) 12 mm Brass Hose Strap- 1 nos
13) 12 mm Hose color -1 nos
14)12 mm GI T - 1 nos
15) 12 mm White hose - 1 nos
16) 25 mm Garden hose- 3 meters
17) 50 mm PVC T - 1 nos
18) 50 mm PVC Elbow-1 nos
19)50 mm PVC Bend-1 nos
20)12 mm PVC Bend-1 nos
21) 50 mm PVC end cap -1 nos
22)50 mm PVC pipe-4 meters
23)12 mm PVC Pipe -1.5 meters
24)25 mm PVC pipe-15 meters
25) Wood reaper -1.5 meter
26) 12 mm GI Clip- 5 nos
27) Filter box- 1 nos
28) Filter box fixing ring mold -1 nos
29) Gutter fixing clamp-5 nos
30) Solvent, m-seal - As per requirement

Design for Water: Rainwater Harvesting, Stormwater Catchment, and Alternate Water Reuse

Reverse Osmosis Definition

2011-07-26T13:02:00.000+05:30

Whenever two solutions are separated by a cell wall (Membrane), a natural transport mechanism take place called osmosis. During osmosis, The solution of lower concentration tends to migrate through the membrane wall which allow the solution to pass, while rejecting the total dissolved solids into the solution of the higher concentration until the two solutions are in the equilibrium. In reverse osmosis, artificial pressure is applied on the concentrated solution side of the membrane, thus forcing water to migrate through the membrane wall into the less concentrated solution.

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Water Purifiers

2011-07-25T20:05:00.000+05:30

Different type of water purifiers are available in the market. We must purchase the product based on our requirement. Our requirement means quantity of water required for our family and quality of the water. Quality means its chemical parameters. If we are using well water sample, we must do a water analysis of the water. The testing must be done in a approved laboratory. Based on that we can ask the Water purifier companies to submit their techno commercial offer.Consider only established product. Cheap product are made from low quality plastic and filter membrane. So it will not give quality drinking water.

Read

Rain water Harvesting

2011-07-25T15:24:00.001+05:30

Rain water harvesting is the one of the best example of saving energy and water. People are worried about the quality of water. You can remove all the impurities in the water by activated carbon filters. Activated carbon is available in the market. You can make your own filter with wire mesh and a bucket or If you are using pumping facility from the storage area, You can buy one Multi-port valve and FRV vessel for filters, along with the activated carbon. It is very easy to assemble and operate. You can use this water for your all needs in your house. If you have any doubt on the quality you can doze chlorine dioxide for disinfecting the water. Dosage is based on the chlorine demand and residual chlorine
Rainwater Harvesting for Drylands (Vol. 1): Guiding Principles to Welcome Rain into Your Life And Landscape

Iron removal unit

2011-07-24T22:27:00.001+05:30

Iron is the one of the metal found in the ground water. It will be in the water in suspended and dissolved form, we must remove it from the water before it used for drinking or washing clothes. The maximum limit for iron in drinking water is 0.3ppm. we are designing the iron removal unit based on the different factors. Amount of iron present in the water and amount of water is to be treated. Iron removal by using chlorine dioxide is always good. Because this method is safe and practical. using manganese dioxide and green-sand have some limitations. This process is pH sensitive. We cannot use this method if iron content is more than 2ppm.
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save water and save energy

2011-07-23T20:46:00.006+05:30

All of us come in contact with water in all aspects of our lives, at homes, offices outdoors and at leisure. We all have that opportunity to save water at all those occasions.I t is up to us to take that opportunity. We are not only saving water but also we are saving energy for the future. We must think about the new technology like water-less urinals and less water toilets.
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