Industry cases - Industrial wastewater treatment and reuse

—— High concentration, color and difficult to degrade, challenging water resource management for sustainable development

The papermaking industry is one of the world's resource-intensive industries. It has a large amount of wastewater discharge and a high pollution load, especially in the bleaching, pulp washing, papermaking and other links. A large amount of difficult-to-treat organic pollutants and coloring substances are released. It puts significant pressure on the ecological environment and also puts higher requirements on the sustainable responsibility of enterprises.
Typical characteristics of wastewater:
Large discharge volume: 50-100 m³ of wastewater is generated per ton of paper products on average, and the daily discharge of large paper mills can reach tens of thousands of cubic meters.
High organic load: COD is usually 2,000-6,000 mg/L, BOD₅ is 800-3,000 mg/L, and the main sources are difficult-to-degrade substances such as lignin, hemicellulose, and resin acid.
High color and difficult to remove: The color can reach 500-2,000 times, and the wastewater in the bleaching section is even worse. It is still easy to show obvious color after conventional process treatment.
High suspended solids concentration: SS concentration can reach 1,000–3,000 mg/L, mainly pulp residue, filler, adhesive, etc.
Large water quality fluctuations and wide pH range: Due to different production batches and raw material types, water quality fluctuates periodically, and the system needs to have excellent adjustment capabilities and stable output performance.