The Present And Future Of Hydrogen Production From Wastewater

The Present And Future Of Hydrogen Production From Wastewater

Hydrogen energy is an important part of the future national energy system and a key development direction for strategic emerging industries, and the development of green and environmentally friendly hydrogen production technology is an important support for building the future national hydrogen energy system and realizing the goal of “dual-carbon”. However, the current mainstream renewable energy technology of hydrogen production from electrolyzed water has very high requirements on water quality, consumes a large amount of clean water, and has the problem of “resource-energy” imbalance. The preparation of green hydrogen from wastewater can simultaneously solve the two major problems of wastewater treatment and freshwater consumption for hydrogen production, which is an ideal strategy to achieve carbon neutrality in wastewater treatment. 

Sewage Hydrogen Production Technology

Common sources of sewage include steel smelting, papermaking, mining, petrochemicals, brewing, food processing, leather and dairy products, etc. The sewage from different industries has different properties. These industries require a lot of treatment to meet the discharge standards before the sewage is safely discharged into the environment. Traditional sewage treatment systems focus on separating or removing pollutants, but these methods usually consume additional energy and fresh water resources. About 380 billion m3 of sewage is generated each year due to sewage treatment worldwide, and it is expected to increase by another 51% by 2050. In addition, sewage usually contains organic matter, rare minerals, acids, alkalis and salts with high added value potential, and current processes lack effective reuse and recycling measures.

Therefore, combining hydrogen production technology with the sewage treatment industry can promote the development of the water industry in a more sustainable and environmentally friendly direction, which can not only improve the benefits of the hydrogen energy industry, but also achieve near-zero consumption of sewage treatment and near-zero landfill of waste. Different hydrogen production processes are required according to the different properties of wastewater. For example, the wastewater from mining, steel industry and leather industry mainly comes from metal processing, so it usually contains heavy metal ions such as zinc, copper, mercury, cadmium, has high conductivity, and contains chemicals such as cyanide that can migrate heavy metals. This makes water electrolysis technology the best choice for treating such wastewater.

For the papermaking, brewing, food processing and dairy industries, their wastewater is rich in organic matter, such as dissolved solids (TDS), so biodegradation hydrogen production technology is more applicable. Through microbial fermentation, these organic substances can be effectively converted into hydrogen. The wastewater of the petrochemical industry usually contains pollutants such as oil, grease, lead and hydrocarbons. The short-chain alkane organic matter makes photocatalytic reaction technology more suitable for hydrogen production. In addition, wastewater from the pharmaceutical, dye and textile industries usually has a high chemical oxygen demand (COD) and a high COD/biological oxygen demand (BOD) ratio. Antibiotics and complex organic chemical components in the wastewater also increase the difficulty of treatment. For these complex wastewaters, more advanced hydrogen production processes, such as the use of piezoelectric materials, may need to be developed to cope with their complex chemical environment.

Therefore, the complexity and diversity of treating different types of wastewater requires a comprehensive treatment approach and complex plant design to ensure the effective removal of various pollutants and achieve water reuse.