What Are The Dangers of High COD Levels in Wastewater?
High COD (Chemical Oxygen Demand) levels in wastewater can cause various harmful effects, primarily impacting the ecological environment, human health, and industrial production. The following is a detailed summary of these hazards:
1. Harm to the Ecological Environment
Consumption of Dissolved Oxygen: Excessive COD indicates the presence of too much organic matter in the water. During decomposition, this organic matter consumes a large amount of dissolved oxygen. The reduction of dissolved oxygen can lead to hypoxia in aquatic organisms, affecting their normal growth and survival, and may even cause mass mortality, thereby disrupting the balance of the aquatic ecosystem.
Accelerated Water Quality Deterioration: As dissolved oxygen decreases, organic matter in the water accelerates decomposition, producing more toxic and harmful substances, such as ammonia nitrogen, further deteriorating water quality and causing greater harm to aquatic life.
Eutrophication: Nutrients like nitrogen and phosphorus in organic matter can promote excessive algal growth under suitable conditions, leading to algal blooms or red tides. This not only consumes large amounts of dissolved oxygen but may also produce toxic substances like hydrogen sulfide and methane, further threatening aquatic life. Additionally, the excessive growth of algae can cover the water surface, blocking sunlight and hindering photosynthesis in other aquatic plants, thus disrupting the balance of the entire aquatic ecosystem.
2. Harm to Human Health
Drinking Water Safety Threat: Human drinking water mainly comes from natural water bodies such as rivers and lakes. When the COD in these water bodies exceeds the standard, it indicates the possible presence of harmful organic substances like heavy metals, pesticides, and chlorinated hydrocarbons. These substances are difficult to completely remove during drinking water treatment, and long-term consumption may cause damage to the gastrointestinal system, liver, nervous system, and even lead to serious diseases such as cancer.
Skin and Gastrointestinal Diseases: Prolonged exposure to wastewater with high concentrations of organic matter can also lead to skin diseases and gastrointestinal health problems.
3. Harm to Industrial and Agricultural Production
Impact on Industrial Production: Many industrial processes require high-quality water resources, and water bodies with excessive COD obviously cannot meet these demands. This may lead to water quality issues in industrial production, affecting product quality and production efficiency.
Impact on Agricultural Production: Irrigation with water that has excessive COD may lead to soil pollution, affecting crop growth and yield. At the same time, these harmful substances may enter the human body through the food chain, posing a potential threat to human health.
4. Increased Water Treatment Burden and Costs
Excessive COD also increases the burden on water treatment facilities, raising the difficulty and cost of treatment. To meet discharge standards, more financial investment and technical resources are required for wastewater treatment, which may put pressure on the economic operation of wastewater treatment plants.
