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Process Analytics Archives - Parshvi Technology (I) Pvt. Ltd.

pH Measurement During Drinking Water Treatment

Aeration of raw water

■ Background
The water which is introduced into our drinking water system must meet the most versatile requirements concerning hygiene but also certain corrosion requirements to protect the water pipes. To produce drinking water of the required quality, there are many different treatment processes depending on the origin of the water.

■ Procedure
A broadly used procedure is the open aeration of the raw water. The raw water can contain disturbing, corrosive carbon dioxide, which is driven off by aeration. Depending on the origin of the water, also iron and manganese compounds are oxidized and then filtered. In that process the raw water is sprayed through pumps and distributed over large surface packages in so-called trickling towers. To increase the efficiency, the aeration space can be blown with air from below in a counterflow process….

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pH Measurements during Sludge Recycling in Biological Wastewater Treatment Plants

■ Background
Besides the clarified water, modern biological wastewater treatment plants produce sludge which mainly consists of the feces-consuming microorganisms.

In a wastewater treatment plant with a size of 500,000 pe that can be 1,000,000 m3 sludge per year, which even after its dewatering still weighs approx. 10,000 t.

However, the sewage sludge also contains undesired toxic components, such as heavy metals, halogenated hydrocarbons, and pathogens. This makes composting impossible and also the agricultural use as fertilizer is controversial
and will be made more difficult by planned legislative projects.

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pH Measurement During Dye Synthesis

Azo Dyes

■ Background:
Azo dyes make up the largest group of synthetic dyes by number. They are used as food dyes, artists’ colors, basic colors for four-color printing (yellow and magenta), as well as textile dyes on a large scale. Over 350.000 t of azo dyes  are used worldwide only for the dyeing of natural fibers.

Azo dyes are characterized by the diazo group, which couples two molecular parts:

or more general

The diazo bridge connects the two components aryl, designated as diazo component, and R, designated as coupling component.

Modern diazo components are, for example:

4B acid and


Coupling components are:


Chromotropic acid and Schaeffer’s acid


To increase solubility and adhesion to fibers such as wool, the sulfo group is introduced. The great variety of azo dyes results from the more or less free variation of substituents in the diazo components as well as in the coupling components:

Example for a modern azo dye:

Start reaction is the diazotation in the presence of hydrochloric acid and sodium nitrite.

The reaction is exothermic and is therefore cooled with ice and it depends on the pH value….

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pH Measurements in Flue Gas Cleaning Plants (Gas Scrubbers)

Flue gas desulfurization (FGD) of fossil fuel power plants and waste incineration plants

■ Background
The combustion of organic material such as gas, heavy oil, and coal in power plants, of domestic and industrial waste in waste incineration plants, but also various process control procedures in the chemical industry result in polluted exhaust gases which must not be released into the environment without secondary treatment.

■ Legal basis
The emission limits for the corrosive gases SO2, SO3, NOX, (HCl, HF) are governed by standard rules which apply throughout the EU. In the USA the Clean Air Act applies. Almost all newbuilt plants, particularly in China and South-East Asia, use this state-of-theart technology so that there are almost no new plants without modern flue gas cleaning.

■ Procedure
From impurities in the source materials to be combusted mainly sulfur dioxide results. There are several procedures to
extract it. In the most cases the most efficiently working so-called “wet procedure” is applied. The sulfur dioxide, which is acidic in solutions, is bound by an alkaline suspension in an absorbtion tower. Mostly a limestone suspension or hydrated lime (milk of lime) are used:

Calcium sulfite accumulates in the lower part of the tower, the so-called sludge. By injecting air (forced oxidation) it is converted into gypsum.

The resulting gypsum is dewatered and can then be used as  building material. Gypsum from waste incineration plants may be more contaminated and must possibly be disposed of. In that way the SO2 emissions have been reduced from 1.6 mio t to 120.000 t within 20 years….

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pH Measurements during Carbonatation for Sugar Production

Today, sugar is one of the most important staple foods of mankind. It is also of enormous economic importance:
Sugar is produced in 127 countries. Sugar cane and sugar beets are cultivated on an area of approx. 25 mio hectares worldwide with a sugar production of approx. 120 mio tons. Cane sugar accounts for the major part (2/3) of the sugar produced compared to beet sugar.

The largest sugar-producing countries are:
India (> 12 Mio t), former USSR, Cuba, Brasil, USA, China, France, Australia, Thailand, Mexico, Germany (4 Mio t),
Turkey, Italy, and Poland (2 Mio t).
In Germany the per-capita consumptionis approx. 35 kg per year.

■ Procedure
Sugar cane and sugar beet contain up to 20 % sugar (chemical: saccharose). Whether sugar cane or sugar beet
serve as source material is only distinguished by different production processes in the beginning, during delivery
and cutting, and by different washing procedures.

The hackled pieces are leached with 70 °C hot water in the so-called diffusion tower. The raw juice produced that way contains almost 99% of the original sugar, however also various organic and inorganic constituents, the so-called non-sugar particles.

The juice is purified using lime and carbonic acid. For that purpose, the sugar plants operate lime kilns where lime stone (calcium carbonate) is heated to produce burnt lime (calcium oxide) and carbon dioxide.

The lime is added to the raw juice as lime milk. In the process, loose calcium hydroxide precipitates are formed which bind the non-sugar particles.

Now, the carbon dioxide is led into this mixture. The lime including the nonsugar particles stably precipitates and can be separated by filtration.

This step is called carbonatation. It is repeated in a second stage.

A clear, light-yellow thin juice with a sugar content of approx. 16% remains, which is further processed for thickening.
The filtrated carbonated lime is used as fertilizer. The sugar is cleaned by solely physical processes (crystalline transformation and centrifugation). In contrast to widespread assumptions, white sugar is not bleached. Brown sugar  only contains more syrup (always brown)….

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Chlorophyll - the “solar cell” of the future

Since 2010, TH Wildau has been operating an algae farming pilot plant south of Berlin, in which a photobioreactor, a methane gas reactor, and a combined heat and power plant have been connected in a closed cycle for the first time.

The main goal of the project – which is intended to provide data for a large-scale plant down the road – is the optimal configuration of the process technology components and reduction of the external energy input to a minimum. In order to measure the pH and oxygen levels, the TH Wildau technicians are deploying Knick Memosens sensors and Memorail analyzers.

Too valuable to burn
In the search for biofuels, science has been focusing on microalgae for a few years now. A variety of methods exist for obtaining combustible fuels from algae: Catalytic processes can be used to obtain fuel from specific types of algae, and fermentation process can be used to convert carbohydrates from algae into bioethanol. Another approach is the  production of methane through anaerobic fermentation of the algae mass. This is the method used in the pilot plant in Wildau.

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High-Precision Conductivity Measurement at Extreme Temperature Differences

Conductivity sensors used in hygienic applications have to withstand regular CIP (Cleaning in Place) and SIP (Sterilization in Place) processes as well as related strong temperature differences.

Therefore, EVER Pharma Jena uses the extremely robust conductivity sensors SE 605 H and SE 680 with Memosens technology from Knick Elektronische Messgeräte.

EVER Pharma Jena GmbH, which was founded in 1950 as VEB Jenapharm and had operated under the name Jenahexal until their acquisition by the Austrian pharmaceutical manufacturer EVER Pharma in 2011, has specialized in the production of aseptic and sterilized preparations in pharmaceutical phials, vials and pre-filled syringes. Today, the annual production capacities of the company amount to 130 million units. The product range includes neurological products, analgesics and hormones mainly for clinic supplies. The EVER Pharma Jena specializes on crystal suspensions as well as on hormone prepa-rations which are produced in strictly separate plants due to the risk of contamination.

Efficient CIP/SIP plant

Because of their wide range of products including different active substances, EVER Pharma Jena decided for a process design where the preparation tanks in the production aren’t connected with the filling via a static pipe system. Instead, the plant sections are decoupled through the use of mobile sterile filtrate tanks. “This allows us to have a significantly more flexible production at a higher product variant”, Martin Reuther, Project Manager at EVER Pharma Jena, says.

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