New Water Treatment Index System toward Zero Liquid Discharge for Sustainable Coal Chemical Processes

Abstract

The shortage of water resources is the major bottleneck for coal chemical industry development. It is imperative to approach zero liquid discharge for coal chemical processes. Varieties of wastewater treatment processes have been developed, but none of them have yet achieved zero discharge in practice. The water quality of reuse does not meet the requirements, resulting in inactivation of microorganisms in the biochemical system and accelerated corrosion and fouling of heat exchangers. These problems can even threaten production and operation. Current water treatment units are pieced simply together leading to unsatisfactory water quality for reuse. Therefore, a new water treatment index system is proposed for ensuring water quality for reuse and zero liquid discharge. In order to establish the water treatment index system, this paper focuses on the study of the whole water treatment process. For better illustration, a water treatment process for zero liquid discharge is established. A mass balance is calculated depending on several practical industrial cases. Analysis shows that the content of polyphenols, PAHs, long-chain alkanes, and ammonia nitrogen is the key for water reuse quality. Therefore, concentration limits for these components in the indexes are carefully studied and determined. The indexes at each joint point between units are determined based on data from current existing treatment processes and technical demands of specific treatment units. Depending on the index system, appropriate treating technologies are selected and optimized. We finally give suggestions on improvement and optimization of water treatment processes for zero liquid discharge.

Zero Liquid Discharge of Ultrahigh-Salinity Brines with Temperature Swing Solvent Extraction

“…16 Where water recovery is applied, a nontraditional supply is generated for fit-for-purpose and even potable use. 18,19 Increasingly stricter disposal regulations and financial incentives are motivating the development of ZLD technologies for waste brines. 20,21 For example, all newly constructed coalto-chemical facilities in China must comply with ZLD rules for waste streams, to conserve local water resources and ecosystems.…”

Measurement and Correlation of Liquid–Liquid Equilibrium Data for Cyclohexanone–Water–Phenol Ternary System

“…In the past few decades, the coal chemical industry in China has developed rapidly, and coal gasification is the basis of coal chemical industry and even part of energy chemical industry. At present, the treatment and recovery of coal gasification wastewater had become a key factor restricting its development. , In response to the new situation of environmental protection, China issued its special plan for the demonstration project of coal deep processing upgrade for the first time in 2017, the first national special plan in modern coal chemical industry, which pointed out that the advanced treatment and reuse of wastewater is the key content of coal chemical industry upgrading demonstration, which is of great significance to promote clean and efficient utilization of coal. , However, due to the limitation of water resources and the lack of receiving water, the “zero discharge” of coal chemical wastewater has become an inevitable choice for the development of the industry. There are large amounts of phenols, ammonia, tar, and other substances in the coal gasification wastewater, , especially the concentration of phenol can reach 5500 mg/L, which is even higher in some production processes.…”

Making Waves: Zero Liquid Discharge for Sustainable Industrial Effluent Management

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