Use of sewage sludge in agriculture

Sludge treatment:

In order to ensure that we all have clean domestic water, basically, every city has a sewage treatment plant. However, the domestic sludge produced by the sewage treatment plant has always been a headache for the environmental protection department, because the sludge is rich in a large amount of organic matter and pathogenic bacteria, insect eggs, weed species, and heavy metal ions, which is easy to produce foul smell and breed mosquitoes and flies. , polluted environment. Currently, three treatment methods are mainly used: landfill, sea reclamation, and incineration. The treatment methods of the prior art are prone to cause secondary environmental pollution and waste a large number of organic fertilizer resources.

Sludge treatment into organic fertilizer:

Domestic sludge is generated after treatment of domestic sewage, and domestic sewage is produced by residents’ toilets, kitchens, and bathrooms, etc. Therefore, domestic sludge is “rich in nutrients”. The organic matter content of the domestic sludge after fermentation by bacteria is generally as high as 50% or more, the nutrient index such as nitrogen, phosphorus, and potassium is between 5% and 7%, and the content of heavy metals is very low, which meets the basic standards of organic fertilizer, and can be used as a fertilizer. use.

Sludge treatment is applied to agriculture as organic fertilizer:

The domestic sludge can be turned into bio-organic fertilizer after microbial fermentation treatment. It is suitable for agriculture, forests, flowers, lawns, and as a substrate for forest tree container seedlings. It can obtain good growth effects. The physical, chemical, and biological properties of the soil are all it has been improved. Thus, the resource utilization of domestic sludge is completely realized.

The sludge treatment process for organic fertilizer:

1. Adjust the water content of raw materials: The sludge obtained in the sewage treatment plant has a relatively high water content, about 75%-80%. It has generally been subjected to anaerobic fermentation and the content of harmful bacteria is not high. It should be transported back to the fermentation plant. Place the raw materials with low water content under the fermentation tank, and then place the water-absorbing auxiliary materials on the top, such as household garbage and crushed crop straws and branches, so that the liquid organic fertilizer can be fully utilized, which can increase the various nutrients in the raw materials. , The water content of the material in the fermentation is 50%-55%.
2. Adding sludge starter (special starter for sludge reduction): adding special starter for sludge reduction to sludge is usually added before fermentation, and the composting machine is used to turn and stir to make the fermentation bacteria evenly mixed with the sludge. When mixed together, the addition amount of starter is generally about 0.1%-0.3%. As long as the sludge starter is applied to the sludge.
3. Pile fermentation: After high-temperature fermentation, it can effectively kill pathogenic microorganisms and roundworm eggs in the sludge, fix heavy metals in the microorganisms, or turn them into insoluble carbonates, and prevent heavy metals from entering the food chain. For the Compost fermentation method, you can click the above link to view the details.
4. Material crushing: Because the fermented materials contain small agglomerates, it is not conducive to the subsequent granulation of the finished product. At this time, the materials can be crushed, and the Fertilizer crusher can be used.
5. Material mixing: The crushed materials are transported to the batching bin, and then sent to the main conveyor by automatic batching, and then sent to the mixer for mixing.
6. Material granulation: Small and medium-sized organic fertilizer plants generally use Disc pelletizer for granulation, which can save investment costs, and the pelletization rate is also higher, which can reach more than 93%. There are three types of particles: large, medium, and small. The angle of the pelletizer must be adjusted to a certain position, and the angle is determined according to the size of the particles. The larger the angle, the smaller the particles, and the smaller the angle, the larger the particles.
7. Drying and cooling of organic fertilizer: The granulated organic fertilizer particles are sent to the dryer through the conveyor for drying, and the dried organic fertilizer particles are sent to the screening machine through the conveyor, and the large, medium, and Small particles and larger particles are sent to the pulverizer through the return belt to be crushed for re-granulation. The intermediate and finished materials are sent to the cooler through the conveyor for cooling. Because the particles have a certain temperature, the particles are sent in after cooling, twice Sieving to sift out the fine powder.
8. Finished product packaging: Send the sieved organic fertilizer granules to the fertilizer packing machine through a conveyor, and the finished bio-organic fertilizer can be obtained by measuring and packaging.