The historic principles of tanning hides are being challenged by a revolutionary process that uses wastewater. BIOSK Chemicals, located in Shangqiu, a city in eastern Henan province, central China, has developed technology capable of constantly using all discharged waters from the beamhouse through the retanning processes. With an impressive legacy and dynamic leadership, the company is embarking on a global strategy to assist tanners with a solution that is not only timely but appropriate for today’s industrial climate. Imagine being able to reduce water usage by over 70%, minimise effluent discharge by up to 70% and lower chemical usage by 30%. This is now a reality and no longer an aspiration.

Established 30 years ago, BIOSK has grown into the largest company specialising in the research and development of tanning processes and the supply of chemicals to the Chinese tanning industry, as well as managing many production and distribution centres around China. Their core products encompass soaking and liming agents, degreasing chemicals, bactericide and fungicides. This is in addition to its recent breakthrough development of wastewater recycling technology.

Eureka moment

The genesis of addressing the challenge to recycle wastewater was based on BIOSK chairman Zhuangdou Zhang’s experience with pollution, together with the need to change the public’s negative perception of tanning. In 2005, with a defined goal, he began his journey. He closed his tannery, and established a research and development test centre, and by using the equipment together with new investments in laboratory materials, he began trials, and became obsessed with developing a solution. To support his efforts, he hired technicians, engineers and scientists. He then expanded his thought process to include medical science, and after four years, in December 2009, after making some radical changes, results improved. He repeated the tests until a eureka moment.

The most interesting aspect of his discovery was that his wastewater recycling technology is a combination of two things: chemistry and process. It is not as simple as adding a secret ingredient, but a change in the concept of managing wastewater and therefore providing tanners with the ability to reuse the effluent stream to create good, consistent leather.

New parts of the process

The traditional tanning process follows the historic principle of using fresh, original ingredients with each new batch of hides processed. This formula requires a continuous flow of clean water, fresh chemicals and associated utilities. Tanning is a batch process operation, but creates a constant flow of effluent and spent liquors all of which must be managed through a complex water treatment system prior to being released to the local municipality. This becomes a reactionary process and managing the waste streams becomes challenging. There are a multitude of initiatives around the globe to address polluting industries and the demands set upon businesses are becoming increasingly strict each year.

Looking at the concept of tanning from a different perspective, BIOSK has taken a proactive approach by applying a waste management methodology to the processing of hides. Instead of dealing with the resulting problem of effluent, it has addressed the symptoms causing the discharge by approaching the issue of reusing the constituents. Imagine only having to charge the float once, and retain the spent tanning liquors for reuse on the subsequent batch. The concept of recycling all tanning waters is a major paradigm change and it appears that BIOSK has developed the key to unlock this untapped resource.

The BIOSK technology works by adjusting and re-engineering the process together with adding certain pharmaceutical agents. This has the effect of turning hindering materials into beneficial agents, essentially turning the multitude of compounds, micro-organisms and enzymes into productive agents that assist in reusing spent liquors. This new technology is also able to enhance the wet-blue product as finished leather quality and yields all improve.

Today, this technology is being used by several large-scale tanneries in China, having been adopted successfully for over three years. BIOSK’s technology has gained several patents in China and it is in the process of applying for patents in several other countries, including the US.

Key benefits of BIOSK’s new technology 

  • Wet-blue yield increases by 3–10%
  • Shrinkage temperature increases by 3–10°C
  • Tear strength increase by 15%
  • Yield of split leather increase by 15–20%
  • Loose surface decreases by more than 20%
  • Chrome and other chemicals penetrate more evenly
  • Water use is reduced by more than 85%
  • Energy use is reduced by more than 25%
  • Solid waste (sludge for example) discharge is reduced by more than 70%
  • A reduction in the use of other resources such as land, equipment, chemicals and labour by more than 80%.