Wastewater from glass factories mainly originates from multiple stages of the production process. According to authoritative publicly available information, it can be summarized into the following categories:
1. Main Wastewater Sources
1.1 Raw Material Preparation Stage: Wastewater from washing, screening, and rinsing raw materials such as quartz sand, soda ash, and feldspar.
1.2 Melting and Forming Stage: Cooling wastewater from glass melting furnaces and molds, usually in large volumes but with low pollutant concentrations. Fluorine-containing wastewater generated from the dissolution of some fluorine-containing raw materials (such as fluorite).
1.3 Post-Processing Steps:
a. Cutting and Edge Grinding: Wastewater generated from the use of water and cooling fluids (containing silica sand, abrasives, lubricants, etc.), with high suspended solids (up to 1800 mg/L) and COD up to 2500 mg/L.
b. Cleaning: Removing oil, dust, silica powder, etc., from the glass surface, generating wastewater containing organic matter and suspended solids.
c. Printing and Coating: Wastewater containing organic matter, heavy metals, or fluorides generated from the use of solvents, inks, coatings, and cleaning nozzles.
1.4 Environmental Protection and Auxiliary Facilities: Wet dust removal systems (such as exhaust gas scrubbing towers) discharge high-concentration pollutants containing viscous substances. This includes equipment and plant area floor washing water, domestic sewage, etc.
2. Typical Characteristics of Wastewater
2.1 High Suspended Solids (SS): Mainly from particles such as quartz sand and glass micron powder.
2.2 High pH Value: Due to contact with alkaline substances such as soda ash, the pH often reaches 9–13.
2.3 Fluoride Content: If fluoride-containing raw materials are used, fluoride ions may exceed the standard (national standard limit 10 mg/L).
2.4 Contains Heavy Metals or Organic Matter: Special glass (such as high borosilicate glass) may introduce lead, arsenic, etc.; deep-processing wastewater contains oil, silane coupling agents, etc.
