The role and effect of zeolite in wastewater treatment

Zeolite is a water-bearing porous alkali metal or alkaline earth metal aluminosilicate mineral with a skeletal structure. It is widely available, has large reserves, and can be reused through recycling. Zeolite's unique structure, resource distribution and recyclability make it one of the most commonly used water treatment agents in wastewater treatment processes and is widely used for wastewater pollutants such as nitrogen, phosphorus, heavy metals and organic matter.

First, it removes nitrogen and phosphorus from wastewater. Nitrogen and phosphorus can cause malignant growth of certain algae and lead to eutrophication of water bodies, thus affecting human production and life. There are many materials and methods to remove nitrogen and phosphorus. Among them, the use of ion exchange and zeolite adsorption properties to remove nitrogen and phosphorus is a hot research topic at home and abroad. 

The mechanism of zeolite removal of ammonia and nitrogen is the adsorption of non-ionic ammonia and ion exchange of ionic ammonia. The reason is that ammonia is a polar molecule and the surface of zeolite is negatively charged, so it has a strong adsorption effect on ammonia. Ionic ammonia nitrogen can pass through the pores and holes of zeolite to reach the surface of zeolite and exchange with cations in the lattice of zeolite such as Ca2, Mg2, etc., thus reducing ionic ammonia nitrogen in water.

Secondly, removal of heavy metals and arsenic from wastewater. Zeolites have high adsorption capacity for heavy metals. Dao-Cheng Luo applied natural porous zeolite particles for the adsorption and removal of heavy metal ions Pb2, Cu2 and Zn2 in mines. He found that the removal of all three metal ions was greater than 98% after adsorption by porous zeolite particles. limani et al. found that sodium modified plagioclase could significantly increase the exchange capacity of heavy metal ions (e.g. Cu2, Pb2 and Cd2), while microwave modified plagioclase could significantly increase the adsorption capacity of AS(III) in water.

Third, removal of organic matter from wastewater. The study by Xia Lihua et al. found that modified zeolites mainly removed organic matter with larger molecular weight, while the removal of organic matter with smaller molecular weight was poor. Sun Tongxi et al. applied activated zeolite on a biological aeration filter for biological pretreatment of micro-polluted source water, which can effectively reduce small molecule organic matter. studies by Altare and others showed that surfactant-modified zeolite can be used to remove various organic matter from oil and gas field wastewater.