What is the treatment method of aquaculture aquaculture sewage and tail water?

The total available nitrogen content in aquaculture water increased with the increase of aquaculture quantity. 5-10% of the feed fed in pond aquaculture was not eaten by fish, and 25-30% of the feed fed by fish was discharged as feces. In terms of nitrogen input, feed accounts for 90-98%, in terms of nitrogen output, fish accounts for 20-27%, deposited nitrogen accounts for 54-77%, in phosphorus input feed accounts for 97-98%, while deposited phosphorus accounts for 72-89% of output, and fish output accounts for only 8-24%. That is, in addition to a small part of the nitrogen and phosphorus content in the feed for the growth of cultured fish, most of the content is deposited in the pond, causing waste and pollution. Excessive feeding of artificial feed, organic fertilizer and biological excrement make the pond contain a lot of organic matter. Dissolved organic matter is the nutrient of bacteria, providing conditions for the reproduction and growth of pathogenic bacteria, increasing the possibility of disease of farmed organisms. Excessive decomposition of organic matter needs to consume a lot of oxygen, which makes the pond prone to hypoxia and the water quality easy to deteriorate, which directly affects the growth of aquaculture organisms.

1. Physical treatment technology of aquaculture tail water. Aquaculture tail water physical treatment technology includes the use of a variety of filter materials with different pore sizes to block or adsorb impurities in the water, in order to keep the water clean, mechanical filtration and foam separation treatment technology is the most obvious effect, in the industrial scale aquaculture tail water treatment has been widely used.

2, chemical treatment technology of aquaculture tail water. Ozone can effectively oxidize the accumulated ammonia nitrogen and nitrite in aquaculture tail water, reduce the organic carbon content and chemical oxygen demand concentration, remove a variety of reducing pollutants in the tail water, and play a role in purifying water quality and optimizing the aquaculture environment. Ozone has the characteristics of high efficiency and no secondary pollution. In addition, the use of chemical agents such as calcium hypochlorite and quicklime in aquaculture as water quality amendments can improve the quality of aquaculture tail water discharge after treatment of tail water, but long-term continuous use is easy to make strains resistant and cause secondary pollution to the aquaculture environment.

If you really want to do tailwater treatment, then the question is, how far are you going to treat tailwater? If according to the environmental requirements of Germany, the water body entering the farm is like, and the discharge is like, this can be achieved, but the cost of realization is high. Aquaculture tail water treatment is nothing more than a mechanical filtration and a biological filtration. Mechanical filtration, simply put, first a coarse filter (300 mesh screen) filter more than 50μm of large particulate matter, such as fish manure, bait, dead fish, fish scales, etc., and then filter more than 20μm of floating matter with a fine filter (4/500 mesh), and finally filter 20μm below with a protein separator; Of course, if you want to cheat, you can just get a sand tank. If you want to really filter the tail water, three mechanical filters are needed. It is not good to use sand tanks because they clog quickly and require constant backwashing. There is also a so-called non-electric filtration device that uses the siphon principle. 

But this kind of coarse filtration can, and actually wastes more water, and is suitable for coastal or riverside areas where water resources are abundant. The above mechanical filtration can remove 99% of the particulate solid, so the remaining is the ammonia nitrogen and other chemical waste in the water, this time you need to use biological filtration. Of course, it is simple that you can make a large pool, which uses silt and water grass, so that ammonia nitrogen and other microorganisms in the silt will react, and then absorb it with water grass and other plants. Since ammonia-nitrogen microbes are light-averse, the water needs to have a certain depth. The first thing to understand is that the so-called ammonia nitrogen is absorbed by plants such as aquatic grasses, similar to human manure fertilization, which needs to be "fermented". I have seen some aquatic test bases, is to excavate a moat around the farm, let the shot tail water around the river after purification and then discharge, so there are coarse stone, fine sand, silt, plants and so on. Above all these, ultimately depends on how big your venue is and how much your capital budget is. If your site is large enough, you can also consider discharging in this way, which is not suitable for large-scale high-density farming, because you will need a larger site to deal with.

 If the site is not large, biological filtration needs to build its own biochemical pool, increase the gas release tower and aeration pool. The gas release tower is similar to the principle of an artificial waterfall, spraying the tail water to the multi-sided object to increase the air contact surface, and the aeration pool is to do the bottom aeration, and put granular bacteria larger than the surface area. If the field is large, it will be artificial swamp, and if the field is small, it can only be biochemical tower.