Wastes Generation in Tanneries


//curated information.

By Salman Zafar, BioEnergy Consult

Wastes originate from all stages of leather making, such as fine leather particles, residues from various chemical discharges and reagents from different waste liquors comprising of large pieces of leather cuttings, trimmings and gross shavings, fleshing residues, solid hair debris and remnants of paper bags.

Tanning refers to the process by which collagen fibers in a hide react with a chemical agent (tannin, alum or other chemicals). However, the term leather tanning also commonly refers to the entire leather-making process. Hides and skins have the ability to absorb tannic acid and other chemical substances that prevent them from decaying, make them resistant to wetting, and keep them supple and durable. The flesh side of the hide or skin is much thicker and softer. The three types of hides and skins most often used in leather manufacture are from cattle, sheep, and pigs.

Out of 1000 kg of raw hide, nearly 850 kg is generated as solid wastes in leather processing. Only 150 Kg of the raw material is converted in to leather. A typical tannery generate huge amount of waste:

Fleshing: 56-60%
Chrome shaving, chrome splits and buffing dust: 35-40%
Skin trimming: 5-7%
Hair: 2-5%

Over 80 per cent of the organic pollution load in BOD terms emanates from the beamhouse (pre-tanning); much of this comes from degraded hide/skin and hair matter. During the tanning process at least 300 kg of chemicals (lime, salt etc.) are added per ton of hides. Excess of non-used salts will appear in the wastewater.

Because of the changing pH, these compounds can precipitate and contribute to the amount of solid waste or suspended solids. Every tanning process step, with the exception of finishing operations, produces wastewater. An average of 35 m3 is produced per ton of raw hide. The wastewater is made up of high concentration of salts, chromium, ammonia, dye and solvent chemicals etc.

A large amount of waste generated by tanneries is discharged in natural water bodies directly or indirectly through two open drains without any treatment. The water in the low lying areas in developing countries, like India and Bangladesh, is polluted in such a degree that it has become unsuitable for public uses. In summer when the rate of decomposition of the waste is higher, serious air pollution is caused in residential areas by producing intolerable obnoxious odours.

Tannery wastewater and solid wastes often find their way into surface water, where toxins are carried downstream and contaminate water used for bathing, cooking, swimming, and irrigation. Chromium waste can also seep into the soil and contaminate groundwater systems that provide drinking water for nearby communities. In addition, contamination in water can build up in aquatic animals, which are a common source of food.

————————————

🕶Biogas Power AdPlugIT

Plan to make use of your MSW or agro-industrial organic waste to generate power or have W2E projects?

We do local turnkey biogas power plant projects. We offer expertise and experience of one of the top ten biogas engineering and construction company in the world- a Germany based corporation with over 400 installed biogas power plants worldwide. 

We are looking forward to serve you in converting your waste into resources.

Biogas Frequently Asked Questions

https://jcgregsolutions.wordpress.com/2016/12/18/biogas-faq/

Waste to Energy. What is holding you back?

https://jcgregsolutions.wordpress.com/2016/10/23/waste-to-energy-what-is-holding-you/

History of Anaerobic Digestion

https://jcgregsolutions.wordpress.com/2016/10/17/a-short-history-of-anaerobic-digestion/

Jess C.Gregorio

InSpecIT Inc.

Unit 719/722 City & Land Mega Plaza Bldg.

ADB Ave. cor. Garnet Road, Ortigas Center

San Antonio, Pasig City, Philippines 1605

Email: gregoriojess@yahoo.com

We do SCADA, BMS, FDAS, FMS, HMI, and Control System Integration.

https://jcgregsolutions.wordpress.com/2016/07/31/over-and-above-scada-bms-fdas-hmi/

Browse JcGreg Flipboard Magazine

https://flipboard.com/@JessGregorio?tab=magazines

Follow JcGreg WordPress Blogs

https://jcgregsolutions.wordpress.com/

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s