The rinse water from five process lines at a plating shop is treated with the closed-loop water treatment systems consisting of Advanced Reverse Osmosis, Electrocoagulation and Electrodialysis. The product water is recycled back to the process lines.
Before the installation of the recycling system approximately 380,000 liter per day of wastewater were discharged from the process lines. With the operation of the closed-loop water treatment system the plant is saving 120,000 cubic meter per year of fresh water.
The company reduced costs for water usage, energy consumption, sludge disposal and chemicals in the wastewater treatment plant.
Table of Contents
1.0 Introduction
2.0 Process Description
2.1. Description of Applied Technologies
2.1.1. Critical and “Non-Critical” Rinses
2.1.2. Critical Rinses
2.1.3. “Non-Critical” Rinses
2.1.4. RO Systems (ROI and ROII)
2.1.5. Electrodialysis System (ED)
3.0 Cost, Water and Energy Savings
3.1. Estimated Water Savings
3.2. Estimated Energy Savings
3.3. Estimated Savings in Wastewater Treatment
4.0 Conclusion and Findings
Project Goals and Scope
This document presents a comprehensive study on the implementation of a plant-wide closed-loop water recycling system for an anodizing and plating facility, aiming to achieve zero liquid discharge while optimizing resource efficiency.
- Engineering and process analysis of industrial rinse water streams
- Implementation of advanced membrane and electrotechnologies
- Reduction of water consumption through circular recycling processes
- Evaluation of energy efficiency compared to conventional systems
- Cost-benefit analysis of wastewater treatment, chemical usage, and disposal
Excerpt from the book
2.1. Description of Applied Technologies
Rinses contain chemicals, which are dragged over from the previous process bath. For the recycling of rinse water, it is necessary to assess the chemistry and the chemical load of the rinses. PPI analyzed the TDS (total dissolved solids) of every rinse and established two different groups of rinses:
• critical or metal bearing rinses
• “non-critical” rinses.
Rinses containing a high concentration of TDS, zinc, chrome and aluminum, are considered critical rinses. Rinses with low TDS and without metals are considered “non-critical” rinses.
Summary of Chapters
1.0 Introduction: This chapter provides an overview of the design and installation project for a closed-loop recycling system across five distinct metal finishing process lines.
2.0 Process Description: This section details the technical configuration of the wastewater recycling system, including the utilization of Reverse Osmosis, Electrocoagulation, and Electrodialysis.
3.0 Cost, Water and Energy Savings: This chapter quantifies the financial and environmental benefits, specifically focusing on reduced water usage, energy consumption, and lower wastewater treatment costs.
4.0 Conclusion and Findings: This chapter synthesizes the project results, highlighting that the recycling system improves water quality while achieving significant annual cost reductions.
Keywords
Zero Liquid Discharge, Water Recycling, Electrocoagulation, Reverse Osmosis, Electrodialysis, Plating Industry, Anodizing, Rinse Water, TDS, Energy Savings, Wastewater Treatment, Industrial Engineering, Metal Finishing, Sustainability, Closed-loop System.
Frequently Asked Questions
What is the primary objective of this project?
The primary objective is to document the design, installation, and operation of a plant-wide closed-loop water recycling system for an anodizing and plating company to achieve zero liquid discharge.
Which metal finishing lines are covered by the system?
The system closes the loop for five lines: the Zinc hand line, Zinc crane line, Large anodizing line, 10 foot anodizing line, and the Small anodize line.
What specific technologies are utilized for water treatment?
The system utilizes Reverse Osmosis (ROI and ROII), Electrocoagulation (EC), and Electrodialysis (ED) technologies, along with ancillary equipment like filters and tanks.
How is the rinse water categorized for recycling?
Rinse water is categorized based on Total Dissolved Solids (TDS) and metal content into "critical or metal bearing rinses" and "non-critical rinses."
How does the system compare to conventional treatment methods in terms of energy?
The proposed closed-loop technology reduces energy consumption by 109,218 kWh/year compared to a conventional wastewater treatment system.
What are the main financial benefits of this implementation?
The plant achieves annual cost savings of $198,779 by reducing expenses related to water usage, energy consumption, sludge disposal, and chemicals.
How is the concentrate from the ROII system handled?
The concentrate (reject) from the ROII system is further processed using an Electrodialysis (ED) system to separate it into a low TDS diluate and a high TDS concentrate.
Why is UV light used in the T-2 tank?
A side stream of permeate in tank T-2 is recirculated through a UV light system to keep the recycled water free from algae and microorganisms.
- Citation du texte
- Dipl.Ing. Christian Tasser (Auteur), 2003, Zero liquid discharge through closed loop technologies, Munich, GRIN Verlag, https://www.grin.com/document/75021
