Frequently Asked Questions

Most Frequently Asked Questions About Water Treatment Systems

Drinking Water Standards

Approximately 40 parameters mentioned in WHO drinking water standards are used in the classification of water. As a result of analyzing these parameters, the suitability of the water for the purpose of use can be evaluated. If only one of these parameters exceeds the standard values, it prevents the water from being used as drinking water.
TDS Total Dissolved Solids

Total Dissolved Solids (TDS) is one of the important parameters showing the mineral and ionic content of water. Because, water in nature differ in terms of TDS concentrations according to their sources. TDS concentration of 1500 mg/l is the upper limit for "Freshwater" sources. Water with 5000 mg/l TDS are generally referred to as "Brackish Water", while water containing more TDS are defined as "Salt Water". The presence of high TDS (> 2000 mg/l) in water is a condition that requires deionization in water for almost every purpose. This type of water can not be used for industrial or social water supply other than limited purposes, and it cannot be used for irrigation water purposes.
Well Water vs. Surface Water Sources Comparison

Fresh water is supplied from surface water (lake, river, pond) sources and underground (well) aquifers. Surface water sources are generally turbid and media filtration is absolutely necessary. Well water, on the other hand, is rich in TDS (total dissolved solids) concentration. However, the well water is of higher quality than surface water resources. During percolation between underground layers, large amounts of solid matter mix into well water in dissolved form. This is the reason why well water is rich in TDS. The TDS value generally found in well water is 500 - 2500 mg/l TDS.
How to filter turbid and sediment water sources?

In general, water sources that have a turbid appearance and leave a precipitate at the bottom are considered to be sedimentary. Whatever the purpose of use of the water is, sediment is a parameter that is not likely to be tolerated. The residue should not be confused with the color parameters. Color generally indicates the presence of dissolved organic matter or heavy metals in water.

It is possible to remove the residue in various ways. Media sand filters, ultrafiltration, automatic disc filters and cartridge filters are some of the systems that serve this purpose. Cartridge filters, which is small in size and inexpensive in terms of cost, only serve as filtering and attention should be paid to the frequent cleaning and periodic maintenance of these devices.

In media filters, filtration takes place not only by the filtering effect but also by the adsorption effect. With the right design, they work very effectively and reliably. However, in the system design, the filtration rate in the tank should be around 5 - 20 mt/hour. In cases high filtration velocity used, the adsorption effect of the filtration system will be lost and the pressure loss will increase.
What is activated carbon filter and where to use it?

The common application area of activated carbon filtration is the removal of organic matter, color, odor, taste and chlorine present in water. Activated carbon systems are systems that make physico-chemical treatment and the adsorption mechanism operates during the treatment of water. Activated carbon is a coal-like material, but with a very large surface area (~1000 m2/gr). It is widely used in organic polluted waters and for free chlorine removal.

One thing to be aware of about activated carbon is that it can create a suitable environment for bacterial growth. Because activated carbon holds organic matter and if there are bacteria in the water, the bacteria can reproduce by using this organic material as food. In such cases, bacteria leakage is possible. For this reason, it is important to disinfect the water before and after the activated carbon.

In the design of activated carbon systems, the filtration velocity in the unit tank should not exceed 20 m/hour for chlorine removal and 6 mt/hour for organic matter removal. In cases higher filtration velocity used, the activated carbon filters will not work efficiently.
How to disinfect water?

Water must be disinfected in order to control the microorganisms in the water. It is possible to carry out the disinfection process in many ways. However, chlorination and ultraviolet disinfection systems are most commonly used methods.

Chlorine has long been the most widely used disinfectant. In addition to being a cheap disinfection system, chlorine has a permanent effect in its widespread use. When chlorine is mixed with water, it reacts with some organic substances and heavy metals in the water. After all reactions have occurred, leaving 0.5 mg/lt of free residual chlorine in the water will prevent microorganism activity up to the point of end use. However, at any point after chlorination, removing the free residual chlorine from the water through the activated carbon system will make the water vulnerable to microorganism contamination after dechlorination process. Even if chlorinated water is passed through the activated carbon system, it is recommended to bypass 0.1 mg/lt of residual chlorine.

However, chlorine is known to cause the formation of carcinogenic chemical compounds (trihalomethane, chloroform, etc.) harmful to human health by combining with some organic substances in water. If the use of chlorine is done uncontrolled, the formation of this type of chemicals is possible. For this reason, the use of different chemicals for water disinfection is increasing day by day. However, today, chlorine is still the most commonly used disinfectant.

Another method used for water disinfection is Ultraviolet Disinfection. In this method, ultraviolet radiation with a wavelength of 254.7 nanometers is used. This radiation causes degradation in the DNA structure of microorganisms in the water and prevents microorganism reproduction. Ultraviolet systems are widely used for disinfection. However, the issue to be considered in these systems is to put the system as close to the end use as possible. In addition, the water coming out of the system should not enter a separate unit open to the atmosphere. Also, in case of voltage drops or power outages, it will be beneficial to have the system connected to a inline UPS system. A voltage drop of only 10 percent can reduce the efficiency of the UV system by 20%. If ultraviolet systems are used in waters with aesthetically turbid appearance, it is essential to remove the turbidity by passing the water through 5 micron cartridge filters with sensitive particle holding capability before the UV unit. Because microorganisms can come out alive from the UV unit as a result of large particles blocking the UV radiation. Periodic maintenance of UV units is also important. It is very important to perform quartz sleeve cleaning periodically, depending on the UV lamp replacement once a year and the raw water quality. Failure to do this cleaning will reduce the UV radiation effectiveness.

What is Water Hardness?

Water hardness is the most common problem in domestic, commercial and industrial uses. Minerals that give water hardness are calcium and magnesium minerals that are mostly dissolved in water. Water hardness classification can be given as follows.

Very soft	0-2 Fr
Soft	2-6 Fr
Medium hard	6-12 Fr
Hard	12-18 Fr
Very hard	>18 Fr

Problems Caused by the Use of Hard Water

The harm of hard water can be given very briefly as follows:

• With hard water, more soap and cleaning products are used for domestic use.

• Hard water causes soap deposits that are very difficult to clean whenever it touches.

• Hardness in water loses its solubility by itself or when the water is heated, and starts to stick to the surfaces it passes through. The inside of the water pipes is quickly filled with limescale, the water pressure and flow decreases.

• Increasing calcification on surfaces where the water is heated causes insulation and increases electricity consumption. Calcification in the heating system causes an increase in fuel consumption.

• Soap curd sticks to human skin after a bath or shower. It clogs the pores of the skin and coats the hair strands and hardens them. This mass that adheres to the skin creates a favorable environment for bacteria to reproduce.

• Hardness minerals give an undesirable taste in food. The ice made with hard water will look like a mist.
How Water Softeners Work?

The most practical way to soften water is to use sodium based ion exchange resins. Ion exchange softener systems generally work by exchanging sodium ions and hardness ions. During the process, water passes through the resin particles. The electrical charge on the resin particles keep the sodium ions on the resin particles. However, resin particles also have the ability to hold hardness minerals. The ability of resin particles to retain hardness minerals is higher than their ability to hold sodium ions. In this way, ion exchange takes place.

After a certain amount of hard water passes through the resin bed, the resin particles are completely covered with hardness minerals. In this case, the binding of hardness ions ends. In order to keep the hardness ions from the water again, the resin particles must be freed from the hardness minerals and the sodium particles must be bound again. This process is called 'regeneration'. During regeneration, brine is fed into the resin tank and the resin is saturated with sodium. The high concentration of sodium ions accumulated in the resin tank separates the hardness ions from the resin particles. The resin is then rinsed with clean water and excess salt and hardness minerals are removed from the tank. The resin tank is ready to remove the hardness ions again.
Can softened water be used for irrigation?

The water sources with hardness above 20 Fr should not be used for any kind of irrigation after softening. Because during ion exchange softening process as the inlet water hardness increases, the amount of sodium given into the product water increases. Sodium, on the other hand, is an unfavorable parameter in irrigation water of plants.
Agricultural Irrigation Water Quality

The concentration of dissolved ions in the irrigation water determines the quality of the irrigation water. The four basic criteria for determining the quality of irrigation water are the conductivity of the water (EC), the sodium adsorption rate (SAR), residual sodium carbonates (RSC), and ion toxicity.

Sodium excess and ion toxicity are the most important problems in agricultural irrigation water. Especially in arid regions where rainfall is less, salt accumulation will occur in the root area of ??the crop. In such cases, the change in salt content in the soil and the quality of irrigation water should be closely monitored. An excess of sodium in irrigation water will cause deterioration of the soil structure and prevent water from penetrating into the soil.

Toxicity; sodium, chloride, boron etc. refers to the critical concentration of other trace elements.

There are four basic criteria for the assessment of water quality for irrigation purposes:

1. Conductivity (EC): excess of total dissolved solids in water

2. Sodium adsorption rate (SAR): The ratio of sodium (Na +) to calcium (Ca2 +) and magnesium (Mg2 +) ions

3. Residual sodium carbonates (RSC): The concentration of bicarbonate (HCO3−) and carbonate (CO32−) anions.

4. Excess of trace elements that cause toxicity in plants

The pH of the water is not a quality criterion in irrigation water. Because the pH parameter tends to be buffered by the soil and most agricultural products can tolerate a wide pH range.

Salinity in irrigation water

High salinity in irrigation water increases the osmotic pressure of moisture in the soil and the access of plant roots to water becomes difficult. That is, although the soil in the field irrigated with salt water appears to be moist, the plants will wilt. This is because plant roots cannot absorb water from the soil due to high osmotic potential. Thus, water lost from the plant through perspiration cannot be reinforced from the soil and fading occurs.

CONDUCTIVITY DAMAGE LEVEL

CONDUCTIVITY	HAZARD
<750 µs/cm	Water suitable for use as irrigation water and where harmful effects will not be noticed.
750 - 1500 µs/cm	Water that can have detrimental effects on sensitive crops.
1500 - 3000 µs/cm	Water that can have adverse effects on many products and therefore requires controlled application.
3000 - 7500 µs/cm	Water that can only be used for salt-resistant plants in permeable soils with controlled application.

Sodium in irrigation water

The criterion for sodium in irrigation water is expressed as the "sodium adsorption rate (SAR)". Although sodium directly contributes to total salinity and can be toxic to delicate crops such as fruit trees, the main problem with high sodium concentration is its effect on the physical properties of the soil. In other words, high sodium water causes deterioration of the soil structure. Therefore, if soil quality deterioration is not desired in the medium and long term, it is recommended not to irrigate the soil with waters with a SAR value> 10 (mmol/l)^-0.5

Continuous use of water with high SAR values causes deterioration in the physical structure of the soil. This deterioration in the physical structure of the soil causes the soil clay to disperse and the soil hardens and compacts when it dries.

Conductivity Classification in Irrigation Water

CONDUCTIVITY	SALINITY CLASS
100 - 250 µs/cm	Low Salt Water (Salinity Class: C1) It can be used for irrigating most crops in the soil.
250 - 750 µs/cm	Medium Salt Water (Salinity Class C2) It can be used for irrigation of plants with moderate salt tolerance.
750 - 2250 µs/cm	High Salt Water (Salinity Class C3) Controlled use may be necessary for salinity control and can be used for irrigation of plants with good salt tolerance.
> 2250 µs/cm	Very High Salt Water (Salinity Class C4) It is not suitable for irrigation under normal conditions, but can be used occasionally in very special situations. It can only be used in a controlled way for irrigating very salt tolerant plants.

Sodium SAR classification in irrigation water

SAR	SODIUM CLASS
< 10	Low Sodium Water (Sodium Grade S1) It can be used for irrigation in almost all soils with little danger of developing harmful modifiable sodium levels of the soil. However, sodium-sensitive products such as stone fruit trees and avocados can accumulate harmful sodium concentrations.
10 - 18	Medium Sodium Water (Sodium Class S2) In fine textured soils with clayey and high cation exchange capacity, it may pose a palpable sodium hazard. It can be used in coarse textured or organic soils with good permeability.
18 - 26	High Sodium Water (Sodium Grade S3) It can create harmful levels of sodium in most soil types. Its use will require special soil management, good drainage, high permeability and high organic matter conditions. However, gypsiferous soils may not generate harmful sodium levels from such waters. It may not be possible to use it in waters with very high salinity.
> 26	Very High Sodium Water (Sodium Grade S4) It is generally insufficient for irrigation purposes, except for low and medium salinity. Specifically, it can make it suitable for controlled irrigation water use when the soil is rich in calcium or if amendment agents such as gypsum are applied.

High quality irrigation water supply with reverse osmosis technology

It is important that the water to be used in agricultural irrigation or landscape irrigation conforms to the irrigation water criteria, both in terms of obtaining yield from the soil to be irrigated for many years and in terms of growing the crop to be irrigated in a healthy way. The water source to be used in irrigation should be examined in detail in terms of conductivity, sodium, SAR, chloride, residual sodium carbonates and boron parameters at the first stage. If parameters that do not comply with the irrigation water criteria are determined among these parameters, it may be necessary to demineralize the water by reverse osmosis method.

Since the irrigation water will not need to be completely pure, partial demineralization with reverse osmosis technology will be sufficient. Partial blending of reverse osmosis product water and raw water may be required to achieve the desired irrigation water quality. The ratio of raw water to pure RO product water to be blended depends on the salinity of the raw water, the water quality required by the crop to be irrigated, and the soil analysis. After ing the irrigation water class according to the condition of the soil and the condition of the crop to be grown, the raw water blending rate can be determined.