Tannery Effluent Recycling Process for Near-Zero Discharge
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Solution Overview
Problem
Current technologies for treating tannery effluents are inefficient and costly, with high energy consumption and limited effectiveness in removing pollutants, leading to ongoing pollution and resource wastage, particularly due to the complex composition and high BOD/COD values of the effluents.
Innovation Solution
A comprehensive recycling process for tannery effluents is implemented across multiple stages of the tanning process, including soaking, liming, re-liming, de-liming bating, pickling chrome tanning, re-tanning, neutralizing, and dyeing, utilizing filtering and recycling equipment to recover nearly 100% of effluents, reducing chemical material consumption and pollution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional treatment technology (activated sludge process) is used, then BOD removal rate is improved (>90%), but energy consumption increases and treatment cost increases
Solution Approach 1:
The patent segments the effluent treatment into multiple specialized stages: anaerobic digestion for organic matter breakdown, aerobic decomposition for further purification, membrane filtration for solid-liquid separation, and UV disinfection for pathogen elimination. Each stage targets specific pollutants with optimized energy input, avoiding the high energy consumption of conventional activated sludge processes while achieving superior removal rates.
Solution Approach 2:
The patent changes operational parameters by controlling temperature, pH, and oxygen levels at different treatment stages. Anaerobic digestion operates at controlled temperatures to maximize organic matter breakdown without excessive energy input, while subsequent aerobic stages use optimized aeration rates. This parameter optimization reduces overall energy consumption compared to conventional single-stage treatment.
2Reliability
If conventional treatment technology is used, then BOD removal rate is improved (>90%), but treatment cost increases
Solution Approach 1:
The patent recovers valuable resources from the effluent: biogas is captured from anaerobic digestion for energy generation, nutrients are recovered during treatment, and treated water is reused in tanning operations. This resource recovery offsets treatment costs and creates economic benefits, making the system more cost-effective than conventional treatment that simply discharges treated effluent.
Solution Approach 2:
The treatment system is designed to be partially self-sustaining through biogas generation from anaerobic digestion, which provides energy for heating and operational needs. The system also uses treated effluent from later stages as input for earlier stages, creating internal circulation that reduces fresh water requirements and associated costs.
3Loss of substance
If effluent is recycled through multiple tanning procedures, then effluent discharge is reduced (near 100% recovery), but leather quality deteriorates (weight gain, shrinkage temperature, grain side damage)
Solution Approach 1:
The patent extracts and removes harmful substances from the effluent through multiple separation mechanisms: anaerobic digestion removes organic matter, aerobic decomposition eliminates remaining pollutants, membrane filtration captures suspended solids and colloids, and UV disinfection eliminates pathogens. This comprehensive extraction of contaminants allows effluent recycling without negative impacts on leather quality, as the recycled water is effectively purified before reuse.
Solution Approach 2:
The patent introduces several intermediary treatment stages between effluent discharge and reuse. The effluent passes through anaerobic digesters, aerobic reactors, and membrane filtration systems that act as intermediaries to remove contaminants. These intermediary processes ensure that by the time effluent is recycled, harmful substances have been eliminated, preventing quality deterioration in the leather product.
4Object-generated harmful factors
If comprehensive effluent recycling is implemented across all tanning procedures, then pollution is reduced, but process complexity increases
Solution Approach 1:
The patent combines multiple treatment functions into an integrated system where anaerobic digestion, aerobic decomposition, membrane filtration, and UV disinfection operate as a unified process train. Effluent flows sequentially through these combined stages, with each stage building on the previous one. This merging of functions achieves comprehensive pollution removal while managing complexity through systematic integration rather than separate isolated processes.
Solution Approach 2:
The patent establishes continuous effluent circulation throughout the tanning process, with treated effluent from later stages being fed back to earlier stages. This continuous recycling creates a closed-loop system that maintains constant treatment action, ensuring pollutants are consistently removed while reducing overall water consumption and discharge. The continuous operation optimizes resource efficiency and simplifies process management compared to batch treatment approaches.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process achieves near-zero effluent discharge, reduces energy consumption, and enhances the quality of finished leather by improving compactness and fullness, while significantly lowering chemical material usage and solid waste production.
Implementation Method 1
utilizing filtering and recycling equipment to recover nearly 100% of effluents
Data Source
AI summary
A recycling process for achieving near-zero emissions of tannery effluent is characterized in that effluent recycling is carried out independently in soaking, liming, re-liming, de-liming bating, pickling chrome tanning, re-tanning, neutralizing, and dyeing procedures. The effluents in the above procedures can be recycled in each step. This process greatly reduces effluent discharge and helps solve the problem of tanning pollution. The process also improves the quality of the finished leather, effectively decreases loose grain rate and increases compactness and fullness of the finished product. The project can reduce chemical material consumption by 15%-55%. For example, the consumption of chromium powder can be reduced up to 65%. Consumption of other chemical materials can be reduced by more than 90%, while certain chemical materials can be essentially completely conserved.