Aquatech's Wastewater Recycle and Zero Liquid Discharge Plant Provides Innovative Solution for China Shenhua's New Materials Project in China
| Challenge: | China Shenhua's 680 KTA coal-to-chemicals plant in Urumqi City encountered difficulties with conventional membrane technology, struggling to process the feed water effectively, and requiring a large ZLD system. |
| Solution: | Aquatech provided a fully integrated Zero Liquid Discharge (ZLD) plant utilizing state-of-the-art AquaEZ™ technology, ensuring compliance with regulations and minimizing water footprint effectively. |
| Customer Benefit: | Aquatech's Zero Liquid Discharge (ZLD) solution showcased effective water management for CTX plants, ensured regulatory compliance, and enabled water recycling and reuse with high-quality water. |
This case study details how China Shenhua Coal to Liquid and Chemical Company utilized Aquatech's water recycling and Zero Liquid Discharge (ZLD) technology to meet strict regional regulations and reduce the water footprint for its coal-to-chemicals plant in Uygur Autonomous Region, China.
Aquatech implemented a HEVAP™ evaporator for brine concentration and a crystallizer to achieve ZLD.
Challenge
Coal-to-chemicals wastewater is complex, with high levels of organics, silica, ammonia, and hardness. This leads to high scaling and fouling potential for membrane systems. Conventional membrane technology would struggle with this feed water, resulting in high rejection volumes and requiring a large ZLD system.
Shenhua selected Aquatech to design, engineer, supply, and supervise the installation and commissioning of this project's wastewater recycling and ZLD system.
Solution
Aquatech, with extensive experience and expertise in commercially proven ZLD solutions worldwide, eliminated the discharge of water from plant operations into the environment by converting it to disposable dry solids and high-quality water for reuse.
Aquatech supplied a fully integrated and automated system with AquaEZ™, a state-of-the-art technology consisting of High-Efficiency Reverse Osmosis (HERO™), high-efficiency evaporation (HEVAP™), and a crystallizer to eliminate liquid discharge from the plant. The AquaEZ plant consists of three systems: water recycling, zero liquid discharge, and recycle water post-treatment.
Water Recycle
The CTX wastewater stream has a high potential for scaling and fouling due to the presence of hardness, organic species, ammonia, silica, and other contaminants. Initially, the HERO system treats this wastewater stream through processes like lime softening, filtration, ion exchange, ultrafiltration, and reverse osmosis membranes, achieving high recovery of low TDS permeate for reuse by the facility.
HERO is a patented process, ideal for applications with feed water high in both organic and inorganic foulants. It operates in a way that eliminates scaling and fouling caused by biological growth, organic species, oil, and grease. As a result, an AquaEZ system experiences significantly less downtime for cleaning.
Zero Liquid Discharge
The concentrated brine from the water recycle system undergoes further concentration in the ZLD system, which recycles the remaining water as distillate. The ZLD system includes a HEVAP evaporator for brine concentration and a crystallizer to achieve ZLD.
The concentrated HERO reject brine from the water recycle system is non-scaling. The HEVAP evaporator is designed with a very low-temperature difference (ΔT) between the heating medium and the boiling brine, along with a high recirculation rate. This design ensures scale-free evaporator operation and lower power consumption.
The crystallizer serves as the final step in brine concentration, further concentrating the brine from the evaporator. During this process, salts are precipitated, grown into crystals, and harvested by a centrifuge. The resulting dry salt is then taken for suitable disposal.
Recycle Water Post-Treatment
The permeate from the water recycle system and the distillate from the ZLD system are treated to reduce NH3 and TOC to specified limits. A stripping tower is used to treat the distillate, and the combined distillate and permeate are further treated using activated carbon and SAC ion exchange columns.
Customer Benefit
Aquatech delivered a reliable ZLD solution for China’s Shenhua Coal to Liquid and Chemical Company plant. Shenhua’s wastewater solution is an important example of a CTX plant’s ability to manage water effectively. This solution is key to the plant’s regulatory compliance and provides high-quality water for recycling and reuse.