Two-Membrane Process Reclaimed Water Reuse Solution for Coal Chemical Whole Plant (UF + RO Deep Reuse)

1. Project Overview

Wastewater Sources: Biochemical tail water of gasification process, circulating cooling blowdown water and concentrated drainage from desalination station, characterized by high COD, high salinity, high hardness and poor biodegradability.

Treatment Capacity: 150 m³/h deep treatment of reclaimed water; product water reused for circulating cooling water and boiler pretreatment make-up water.

Inlet Water Quality: COD ≤ 80 mg/L, TDS ≈ 1800 mg/L, turbidity ≤ 10 NTU; Reclaimed Water Control Indicators: COD ＜ 20 mg/L, TDS ＜ 300 mg/L, turbidity ＜ 0.5 NTU.

Core Process: Biochemical Effluent Pretreatment→Ultrafiltration (UF) System→Reverse Osmosis (RO) Desalination System→Graded Reuse.

2. Complete Treatment Flow

Biochemical Effluent Regulation Tank→Pipeline Mixer→High-efficiency Softening Sedimentation Tank→Multi-media Filter→Activated Carbon Filter→Self-cleaning Filter→Ultrafiltration System→UF Product Water Tank→5 μm Cartridge Filter→Reverse Osmosis System→Reclaimed Water Tank

RO Concentrated Water→High-pressure Concentrated RO→Concentrated Brine Storage Tank (Supporting MVR Evaporation and Crystallization for Zero Liquid Discharge in Post-stage)

3. Core Unit Description of UF + Two-Membrane Process

3.1.Ultrafiltration System (Core of Reclaimed Water Deep Pretreatment)

Special high anti-fouling PVDF hollow fiber membranes for coal chemical industry with pore size of 0.03 μm accurately intercept residual colloids, zoogloea and suspended impurities in biochemical tail water. Equipped with air-water combined backwashing and online chemical cleaning procedures, it features strong resistance to organic fouling. The outlet water SDI remains stable below 3, ensuring long-term stable operation of the reverse osmosis system and extending the offline cleaning cycle of membrane elements to more than 90 days.

3.2.Reverse Osmosis System (Core of Reclaimed Water Desalination & Reuse)

Equipped with high anti-fouling brackish water dedicated membrane elements with designed recovery rate of 75%, which can remove 98% of dissolved salts and more than 75% of organic COD in water. The product water quality fully meets the requirements of circulating cooling water and miscellaneous plant use. Concentrated water enters high-pressure concentrated RO for further concentration, drastically reducing the treated water volume of subsequent evaporation and crystallization, and lowering the investment and operation energy consumption of zero liquid discharge systems.