Why can't the sludge generated after municipal sewage treatment be directly used for land use? The sludge of the sewage treatment plant does not meet the land cultivation and utilization standards. What does sewage treatment plant sludge contain? 80% of water; 10% of organic components, pathogenic microorganisms, heavy metals, toxic compounds, toxic organic matter, grid debris, etc.

If it is used, sludge digestion treatment is required to remove pathogenic bacteria and stabilize organic components; for impurity removal, drying, crushing, moisture removal, and granulation; removal of heavy metals and refractory macromolecular organics. If this land farming and utilization standard is realized, the technical cost and promotion cost will be extremely high.

The properties of different sludges vary greatly. For example, the surplus sludge generated from the treatment of domestic sewage may not contain so much heavy metals, but the phosphorus content discharged with the sludge is much higher than that of conventional soil, and it is not suitable for direct use in agriculture. As for other types of sludge, it cannot be used directly because of various substances exceeding the standard.

Even if the nutrient content of sludge is beneficial to plant growth, the particle properties can also be used for land improvement, but these applications are limited to feed crops and non-human consumption, and the possibility of using it to support edible plants is under study. The main limiting factors for the application of sludge land are the toxicity of plant-enriched metals and the eutrophic pollution of water bodies. Sludge treatment is an important part of sewage treatment. The quality of sludge treatment directly affects the effect of sewage treatment. If the nutrient content and some pollution in the sludge flow into the water environment in agricultural irrigation, the previous water treatment is equal to white treatment. . Just as the treated sewage can be used for industrial cooling and urban landscape irrigation, but cannot be directly drunk, the agricultural sludge treatment technology that can be used for direct human consumption is not yet mature.