Process Sequence of Biological ETP

Emdadul Haq 

Lecturer, Department of Textile Engineering, Primeasia University; Bangladesh 

Effluent Treatment Plant or ETP is one type of waste water treatment method which is particularly designed to purify industrial waste water for its reuse and it’s aim is to release safe water to environment from the harmful effect caused by the effluent. Industrial effluents contain various materials, depending on the industry. Some effluents contain oils and grease, and some contain toxic materials (e.g., cyanide). Effluents from food and beverage factories contain degradable organic pollutants. Since industrial waste water contains a diversity of impurities and therefore specific treatment technology called ETP is required. The ETP Plant works at various levels and involves various physical, chemical, biological and membrane processes to treat waste water from different industrial sectors like chemicals, drugs, pharmaceutical, refineries, dairy, ready mix plants & textile etc.

Important Dyeing Terms & Definitions

👉Adsorption 

Dye molecules when come to the contact of the textile fibre. Dyes do not penetrate into fibres rather stay on the surfaces of textile materials.

Affinity | Substantivity | Colour Yield | Liquor-to-goods ratio

Affinity: is the attraction of dye to the fibre at normal condition of dye bath. It defines the quality of the dye. Affinity of a dye does not depend on any external factors such temperature, M:L, type of fibre or concentration of electrolyte etc. Initial absorption of dyes due to affinity is called the color strike.

Substantivity: is the attraction of dyes to fibre at changed condition or precise condition. Substantivity of a dye depends on various external factors such temperature, M:L, type of fibre or concentration of electrolyte etc. It is the tendency of a dye to move from a solution into fibres during dyeing condition.

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Solution to effluents treatment । Sustainable Wastewater Treatment

Bangladesh is one of the most promising textile producing countries in the World. With the blooming contribution to the national economy, it, unfortunately, is suffering from some environmental sustainable critical issues. Bangladesh is a riverine country having plenty of water resources. But regret to mention that most of the rivers and canals are becoming increasingly polluted from industrial wastewater dumped by factories especially the textile industry. The chemicals and wastewaters discharged from the industry like dyeing, printing, washing industry are harshly dangerous to the environment, and as a result, water bodies, aquatic sediments, soils become polluted and eventually, aquatic animals and agricultural products are being damaged.

Textile Testing Lab

Testing 

To evaluate how something works under certain established methods or test standards. Textile testing is to check its properties under certain conditions in a standard environment prescribed as per Test standards. 

Types of Testing?

Destructive testing: The testing which breaks the test specimen and goes as waste after testing is called destructive testing. For example, tensile test, compression test, bending test etc. 

Nondestructive testing: The testing in which test materials do not go as waste after testing is called non-destructive testing method. For example, thermal and electrical conductivity testing.

Why testing?

- To check the quality and suitability of raw material;

- To monitor the production (process control);

- To assess the quality of final product;

- To investigate the faulty materials;

- To set standards or benchmarks;

- For R&D (research and development) purpose;

- For new product development.

Testing laboratories play an indispensable role in the execution of a garment order. Various types of standardized testing are required by the customers in every stage of product development like the yarn stage, fabric stage, garment stage, etc. In addition, quality executives carry out various tests at each level to ensure the quality of the material. These labs are divided into the following three categories from the point of functionality.

1. In-house Lab

2. Buying house Lab

3. 3rd Party Testing Lab

In-house Lab: 

Every manufacturing plant has the testing laboratory facilities along with the production unit. The main function of this type of lab is to ensure the right quality of the items like yarn, fabric, garments etc. Yarn count, composition, hairiness, twist factor etc. are tested and maintained to a standard limit for the yarn manufacturing plant. Fabric structure, dimensional stability, weight, spirality, standard shade and colourfastness properties, etc. are tested for the fabric manufacturing plant and the testing lab at garments check the quality of stitches, seams, and different measurements, etc.

Buying house Lab: 

This is actually the customer nominated lab up to their standards. Fabric technologist working at the buying house execute various types of test sought by the ultimate buyers. The vendors send the items to the buying house for approval and of course, they send after doing the in-house tests. Despite that buying house lab test is to ensure everything is as per the standards as mentioned in the PO or other technical package. After testing, checking and evaluating, buying-house gives approval to the vendors to proceed. Sometimes, items should be sent to the original buyers for approval for special issues. 

3rd Party Lab: 

Sometimes, customers do not have the testing setup and they then nominate some well-recognized and standard laboratory to work on behalf of the customers. These labs are termed as the 3rd Party Lab. This type of lab is designed only to test and providing certificates. While issuing an order, customers seek some standard tests done at every stage along with the products from vendors. Yarn count, fabric structure, weight, spirality, colourfastness, presence of hazardous materials, embellishment durability test, overall appearance test of the garments are the most common tests done in the 3rd party testing lab. Another very important function is doing an inspection after the production and they issue gate pass to ship the items to the customers. SGS, Intertek, TUVSUD, Bureau Veritas are some of the most renowned and reliable 3rd party testing labs.
Reference: A Practical Guide to Textile Testing by K. Amutha (Woodhead Publishing)

Lab Dip & Yarn Dip

Vendors get colour standards for all the colours mentioned in the purchase order (PO). Getting colour standards from customers' end may be in two forms as (1) physical colour swatch or (2) phantom number. Next, merchandisers have to make the colours developed by the dyeing unit and send it to the customer for shade approval to proceed on the subsequent processes. The colour development can be either in yarn form or in fabric form. 

Yarn form/Yarn dip: If yarn dyeing is required for the order, not fabric solid dyeing, in that case, colours should be developed in yarn form and it is called yarn dip. Yarn dip with more than 3 options is sent to the customer for approval. 

Fabric form/Lab dip: IF the order requires fabric solid dyeing, then colours should be developed in fabric form and it is termed as Lab dip. Likewise, the yarn dip, more than 3 options are sent to the customer for shade approval. Next, with the approved shade recipe, bulk dyeing will be accomplished. 

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