recycle@source solutions

7/28/2019 Recycle@Source Solutions

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Recycle@Source:

A new tool for greenchemistry

Recycle@Source:


Magazine

www.specchemonline.com

NOVEMBER 2012Volume 32 No. 11

Nitesh Mehta and Dr Komal Maheshwari of Newreka GreenSynth Technologiesintroduce a means to recycle process water indefinitely

Recycle@Source:


Newreka_p33-34_36_scm11_Newreka 2/14/13 11:43 AM Page 1


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The global chemicals industry is

worth $4 trillion/year and is

growing continuously. Certain

sectors, like pharmaceuticals,

speciality chemicals and fine

chemicals, have been and will

continue to grow at a higher rate.

This brings certain challenges with

regard to environmental impact. To

sustain its current growth rates, the

industry will have to address the

challenge of the high E-factor (kgswaste generated/kg of product)

associated with its manufacturing

processes.

The current reality

On average, in the pharmaceuticals,


chemicals industries, three to nine

steps are used to make a specific

product, each using two or three

raw materials, a reaction medium

and an extraction medium to

extract and isolate the product

(Figure 1). At the end, there is a

finished product and an effluentstream containing reaction and

extraction media, some by-products

and some organic and inorganic

impurities.

The manufacturing of these

complex molecules involves

chemistry-intensive processes and

yields are low, due to low

conversion, low selectivity and low

separation efficiency. In addition, a

lot of purification and washing of

intermediates and finished product

is needed to achieve the stringent

quality specifications that

characterise the pharmaceuticals,


chemicals industries. All these

factors lead to a high E-factor.

The effluent stream generated

from each process step has its own

characteristics. These vary from one

effluent stream to another in terms

of physical properties (colour, pH,

temperature, etc.), chemical

composition (concentration andtype of organic and inorganic

impurities), volume generated, other

characteristics (chemical oxygen

demand (COD), biological oxygen

demand, total dissolved salts (TDS),

ammonical nitrogen content, etc.),

toxicity and hazard factor.

A typical manufacturing site of a

pharmaceuticals, speciality

chemicals or fine chemicals

company usually has multiple

production blocks, some dedicated

to regular products and some for

campaign-based products. Each

product would involve multipleprocess steps with different

chemistries and the effluent

generated after the end of each

process step has at least three to

four different chemicals.

Current practice

Current industrial practice is to

collect and mix all these effluents

together so that the acidic streams

partially neutralise the alkaline

stream and the neutralisation cost

during primary treatment can be

reduced. This mixing creates a

cocktail of 40-50 different

chemicals. It is impossible to

separate or reycle them or to

recover any solvent or product; the

only option is to take the effluent

for some end-of-pipe treatments

like aerobic or anaerobic treatment,

biological or biochemical treatment,

incineration, etc.The key issue here is that this just

converts one form of waste into

another. Most of the time, we have

very little or no idea about the

ecological impact of these

molecules. Hence, this is potentially

a huge threat to human health, our

water and other living creatures. It

is also a cost-centric approach to

dealing with waste and hence adds

up to the cost of production. Finally,

it is a tremendous waste of

resources.

Green chemistry &

engineering

Here is where green chemistry and

engineering can play a vital role

now and in future. They address the

environmental challenges at the

source level, rather than on treating

waste after it is generated. Green

chemistry and engineering is

nothing but an approach or a place

to come from while we are

designing or manufacturing a

product or a process.

The 12 Principles of Green

Chemistry and the 12 Principles ofGreen Engineering provide a

framework to chemists and

chemical engineers inside which, if

any product or process is

developed, it will be greener than

the conventional alternatives. They

are a set of guidelines to think

from while designing or developing

or commercialising a product or

process - not so much a description

of a distinct industrial segment thana way of carrying out industrial

activities from design to

manufacturing.

All of this might seem

significantly challenging and

frustrating as we go though the

laboratory and scale-up. However,

the rewards are enormous, as the

process chemistries become simple

to execute. Approaching a product

from the standpoint of green

chemistry offers not only quality

product but also lowest cost

product. It minimises raw material

use, energy use and waste

treatment costs.

The use of green chemistry will

continue to grow rapidly in the

coming decade, offering significant

direct cost savings and indirect

savings in the form of avoiding

liability for environmental and social

impacts. The total amount saved is

estimated to reach $65.5 billion by

2020. Just by bringing inefficient

companies up to the baseline

standard of the industry as a whole,

it is possible to capture more than

$40 billion in cost savings andavoided liabilities.

Nitesh Mehta and Dr Komal Maheshwari ofNewreka GreenSynth Technologies introduces a means to recycleprocess water indefinitely*

Green chemistry

Reprinted from Speciality Chemicals Magazine November 2012 www.specchemonline.com

Recycle@Source: A new tool forgreen chemistry

Step 1

Step 1

Step 2 Step 3 Step 4

2-3 raw materials

Reaction medium

Extraction medium

Intermediate/product

Effluents

Reaction & extraction medium


By-products

Organic impurities

Inorganic impurities

Step 1

Step 1

Step 2 Step 3 Step 4

2-3 raw materials

Reaction medium

Extraction medium


Effluents

Reaction & extraction

Medium

By-products

Organic impurities

Inorganic impuritiesRecycle@Source

Figure 1 - Current industrial practice

Figure 2 - Recycle@Source concept



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Overall, green chemistry

represents a market opportunity

that will grow from $2.8 billion in

2011 to $98.5 billion by 2020,

according to a recent report by Pike

Research. The evolution of green

chemistry-based practices is being

driven by a combination oftechnical, regulatory, consumer

preference and economic factors.

Aqueous effluent streams

To get a sense of the volumes of

aqueous liquid effluent streams we

are dealing with, let us engage in

some order of magnitude

calculations for one of the industry

sectors, pharmaceuticals. Around

750,000 to 1 million tonnes/year of

drugs are produced worldwide.

According to Professor Roger

Sheldon, the average E-factor is 50-

100, i.e. 50-100 kgs waste/kg ofdrug. Of this, about 20% is

aqueous. This means that

pharmaceuticals industry generates

15 billion litres/year of aqueous

liquid effluent, enough to fill 1.5

million tankers. This effluent is very

toxic and has a COD of 50,000-

200,000 mg/litre. One litre of such

a high COD aqueous stream could

potentially contaminate over 1,000-

10,000 litres of fresh water.

When we consider the whole of

the fine and speciality chemicals

sectors too, the numbers are hard

even to imagine. These effluent

streams may contain complex

organic molecules (mostly non-

biodegradable, many carcinogenic),

inorganic products, acids, alkali,

traces of solvents and various heavy

metals (such as nickel, palladium,

platinum, etc), about which littleecotoxicity data is generally

available.

The current industrial practice of

taking such aqueous liquid effluent

streams for primary and secondary

treatments is not effective because

such treatment techniques are not

capable of breaking down complex

organic molecules and because it is

based on the fundamental premise

that the same treatment would

work for all the different kind of

molecules present in an effluent

stream, which is not possible. All

this presents a huge health andenvironment problem.

Moreover, since less than

0.007% of all the water on our

planet is potable and since by 2050

we will have additional 3 billion

people on planet needing drinking

water every day, it is clearly critical

for the chemicals industry to reduce

the consumption of fresh water in

its processes and ensure that no

aqueous liquid effluent stream -

especially those containing various

toxic chemicals - is disposed of to

the environment.

Recycle@Source

As discussed above, any process

step in a multi-step synthesis will

include two or three raw materials,

a reaction medium and an

extraction medium. At the end, we

get an intermediate or finished

product and an effluent streamcontaining reaction and extraction

media, some by-products and some

organic and inorganic impurities.

Usually the major component of

the reaction mass is the reaction

medium. On average, raw materials

and reagents contribute only 20%

of the reaction mass. The remaining

80% is the reaction medium,

which, after the isolation of the

intermediate or finished product, is

converted into liquid effluent.

In most cases, the reaction or

extraction medium we use is what

comes out as the key component ofthe effluent stream. For example, a

diazotisation-hydrolysis chemistry in

dilute sulphuric acid medium, after

intermediate and product isolation,

in most cases generates a dilute

sulphuric acid-containing effluent

stream. Similarly, nitration chemistry

would generate a nitric-sulphuric

mixture-containing effluent stream.

If the effluent stream generated is

similar in its composition to the

reaction or extraction medium, why

can we not recycle it back in the

same process step as reaction or

extraction medium? Currently, thiscannot be done because organic and

inorganic impurities would build-up

in the system and at some point will

start affecting the purity of the

intermediate and finished product.

In Recycle@Source** systems, the

effluent stream is treated with a

customised proprietary performance

additive (RCat**), which selectively

removes the organic and inorganic

impurities to the maximum possible

extent, without removing the

intermediate or finished product

(Figure 2). Thus the same stream can

be recycled back into the same

process step as reaction or extraction

medium - hence the name.

This is not the same as

conventional zero liquid discharge

systems where treated water is

reused in ways other than the

process from which it was

generated. Recycle@Source, means

recycling the entire liquid effluent

stream generated from a particular

process, back to the same process. It

is inherent, a profit centre,

systematic, preventative, simple,

integral and in-built. Recycle@Sourceenables the industry to:

Eliminate or minimise the liquid

effluent load

Increase productivity, where

effluent load handling is a

limitation to expanding capacity

Enhance yield, as intermediate or

finished product being lost in the

aqueous effluent stream isrecycled back

Ensure consistent quality (RCat

does not allow impurities to build

up)

Improve overall economics

Reduce the cost of effluent

treatment and disposal

This is illustrated in two case

studies below

Case Study 1

The conventional process in the

prodcution of an intermediate for

an anti-retroviral drug used Raney

nickel as a reduction catalyst, with asolvent as the reaction medium and

another for product extraction.

Green chemistry was implemented:

the solvent was replaced with water

as a reaction medium, Raney nickel

was replaced with a proprietary,

non-pyrophoric and safe to handle

reducing agent and high pressure

was replaced with atmospheric

pressure, a temperature below

100C and a pH of 5-7.

In the conventional process,

solvent is distilled out, mass cooled

and chilled to isolate amine. In the

green chemistry process, by contrast,product was isolated out and the

aqueous mother liquor was

completely recycled back, after

treatment with RCat, to remove the

impurities selectively more than 500

times at commercial scales. Even

after 500 recycles of aqueous stream

back into the process as a reaction

medium, the quality of amine is

consistently 99%+ on HPLC.

In the last three years, the

customer has not used fresh water

in the batches, except to make-up

for evaporation loss. Yields have

improved by 10% compared to the

conventional catalytic

hydrogenation process (Figure 3a).

This has saved over 1 million litres

of fresh water. The product amine

quality is consistently more than

99% on HPLC with 10% yield

improvement per recycle.

Case Study 2

H-acid is one of the oldest and

largest volume dye intermediates

being manufactured. India alone

produces 20,000 tonnes/year. H-acid

is known as one of the mostpolluting intermediates in this

Green chemistry

www.specchemonline.com Reprinted from Speciality Chemicals Magazine November 2012

AmineMethanol

Caustic

More than 15 recyclesE-factor = 90%Patented technologyYield = 10%

bFusion &

evaporationIsolationvessel

RCattreatment

Centrifuge

RCat

Mother liquor recycle Storagevessel

Acidic mother liquor

H-acid SpentRCat

Filter

Reduction Isolator R-cattreatment

Nitro

GreenCat (GCat)

Newreka

Green Catalyst

1,000 & 100,00 litresMotherliquor

RCat

Centrifuge

Green amine

Filter

Spent GCat

a

Figure 3 - Use of Recycle@Source in pharmaceuticals (a) & dyes (b)

industries



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industry sector, with an E-factor of

about 50, and this waste contains

carcenogenic naphthalene-based

molecules. The high E-factor is also

an indicator of process inefficiency.

Only 53% of theoretical yield is

achieved.

While working on any molecule,it is important to study the E-factor

of all process steps involved in its

manufacturing, identify the most

polluting steps and give priority to

the one which generates maximum

waste. If a green chemistry- and

green engineering-based

technology or solution is created for

the environmental challenges

associated with such a process step,

it can make a significant difference.

For example, H-acid is a five-step

process but 50% of the total waste

is generated from the final isolation

process. Hence, Newreka focussedon creating a solution for the

aqueous effluent stream generated

from this step because this had the

potential to address 50% of the

environmental challenge (Figure 3b).

In the conventional technology,

the thick and highly alkaline

reaction mass after fusion reaction

is diluted with water and then

taken for final product (H-acid)

isolation, which is done by

adjusting the pH to around 1.5-2,

using dilute sulphuric acid. The

mass is then cooled and isolated

product is filtered.

A highly acidic mother liquor gets

generated which is deep red in

colour, with a COD of 150,000 andTDS of 15-25%. Currently, this

effluent is taken for some end-of-

pipe treatment but none of the

conventional primary or secondary

treatments can break down the

naphthalene-based organic

molecules in the mother liquor.

Each kilo of H-acid generates 25

kgs of hazardous aqueous effluent

stream.

Using Recycle@Source, it has been

possible to recycle this mother liquor

back into the process to dilute the

reaction mass obtained after fusion

more than 15 times, which reducedthe effluent load by 90%. The

mother liquor obtained after

isolation is taken for treatment with

RCat selectively to remove undesired

impurities, then recycled back into

the process instead of water. This

solution gives an overall 10% rise in

yield. Even after 15 recycles, the

quality of H-acid is consistently as

per the standards.

Conclusion

The speciality and fine chemicals

industries are dealing with major

economic and environmental

challenges and cannot sustain their

current growth rates without

addressing these. Current end-of-

pipe treatment is not a sustanableoption as most of the time it just

converts one form of waste to

another. It is also a cost-centric

approach and increases the overall

cost of production.

Green chemistry- and

engineering-based innovations

offer tools to the industry to

address both economic and

environmental competitiveness

simultaneously. Implementing

these technologies enables the

industry to deal with its

environmental challenges and

enhance its profitability. It is criticalto add such new technologies and

solutions so that different kinds of

waste streams, for which the

industry does not have a solution

yet, can be addressed.

Recycle@Source is one such new

tool, which gives a short term,

workable strategy to reduce the

effluent load through a profit-

centric approach. The recycle of

the reaction and/or extraction

medium back into the same

process offers enhanced yields,

saving in raw materials, increased

productivity and lower effluent

treatment cost. Most importantly,

it saves water.

The example of a pharmaceuticalintermediate where Recycle@Source

has been commercialised

successfully and in the last three

years the same water has been

being recycled back into the process

over 600 times proves that it is

possible to achieve inherent infinite

recycle with consistent quality of

product without and buil-up of

impurity.

* - Also contributing to this article were

R. Moholkar, R. Angreji, M. Anvekar, M.

Shah and K. Shukla, all of Newreka

** - Recycle@Source and RCat are trademarks of Newreka Green Synth

Green chemistry

Reprinted from Speciality Chemicals Magazine November 2012 www.specchemonline.com

Nitesh Mehta

Newreka Green SynthTechnologies

Tel: +91 22 2879 1835

E-mail: nitesh.mehta@

newreka.co.in

Website: www.newreka.co.in

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