High-quality bricks have been produced from wastewater treatment waste.

In water treatment facilities across Russia, various chemical reagents and filtering materials, such as coal and sand, are utilized. During the operation of these stations, waste sludge accumulates, which is traditionally stored in landfills. The annual volume from a single city can exceed three thousand tons. Currently, the scientific community is exploring effective disposal methods, including extracting valuable components from industrial waste for commercial use. Researchers at Perm Polytechnic University have investigated the potential for repurposing water treatment waste in the construction industry, particularly in the manufacturing of ceramic bricks. The identified properties of the sludge and their processing parameters will ensure the production of a high-quality product and expand the application possibilities for these multi-ton waste materials.

2025-01-31 10:01:47https://naked-science.ru/article/column/othodov-vodoochistki-kirp

Previously, PNIUP conducted a study on the potential of producing building materials using waste from the forestry industry.

The article detailing the results has been published in the collection "Innovations in Construction. KNAUF Technologies." The research was carried out as part of the strategic academic leadership program "Priority 2030."

Currently, progressive methods of utilizing wastewater sludge are being actively researched, where components useful for chemical, metallurgy, and other industries are extracted from technogenic raw materials. However, its most widespread use has been in the construction sector for the production of binding agents, porous fillers, and ceramic materials.

Such waste can be used as a modifier in brick production. Nonetheless, the methods currently proposed for its extraction and incorporation into ceramic compositions have their drawbacks; for instance, the final product does not always meet the required strength and frost resistance. Additionally, using the raw material in its initial state is challenging due to its significant moisture content—over 45-60 percent. For quality processing into a new material, various technologies for compaction, conditioning, and mechanical dewatering need to be added.

Scientists at Perm Polytechnic University have studied the characteristics of using coal waste and sludge generated from a large water treatment plant, identifying the optimal parameters for their incorporation and firing within the ceramic mass.

The chemical treatment of water results in the formation of sludge, which consists of water-soluble aluminum sulfate, small amounts of iron sulfate, and other compounds. It represents a fine-grained mixture, and its elemental composition is similar to clay raw materials, allowing it to be considered as a modifier for clay mass in the production of ceramic products. Coal waste is a loose dry mixture resembling black sand, primarily composed of carbon and sodium sulfate.

"To assess how both types of waste from the water treatment station affect the properties of clay raw materials, we prepared compositions to determine some of the most important indicators: density, plasticity, and molding moisture. These factors subsequently influence the strength, frost resistance, and crack resistance of the final product. We also investigated their optimal content in the ceramic mass: sludge at 10, 20, and 30 percent, coal waste at 10, 15, and 20 percent, and firing temperatures of 950, 1000, and 1050°C," explains Vitaly Shamanov, Associate Professor of the "Construction Engineering and Materials Science" department and Acting Dean of the Construction Faculty at PNIUP, Candidate of Technical Sciences.

Polytechnic researchers note that compared to the additive-free composition, the ceramic mass containing 20 percent sludge shows a 71 percent increase in plasticity, indicating a greater functionality of the studied waste in industry.

"The results of the experiments showed that introducing more than 20 percent of coal waste and more than 30 percent of sludge is impractical due to a significant deterioration in molding properties. However, incorporating 14.2 and 15 percent of waste, respectively, at a firing temperature of 1050°C allows for the production of items with the required density and water absorption levels," explains Vitaly Shamanov.

The research conducted by scientists at Perm Polytechnic University demonstrated that the joint incorporation of wastewater treatment plant waste into the clay mass would comprehensively improve the physical properties of ceramic bricks. The implementation of the obtained results in the processing of sludge will enhance the prospects for their secondary use in the construction industry.