Simultaneously improve the yield of duckweed starch and crude protein and the removal rate of nitrogen and phosphorus in sewage

Abstract

The invention provides a method for simultaneously improving the yield of starch and crude protein of duckweed and the removal rate of nitrogen and phosphorus in sewage. The method is operated by the following steps: inputting the sewage into a sewage treatment pond in a closed and transparent greenhouse; then inoculating the duckweed on the surface of the sewage; introducing CO2 into the greenhouse every day, wherein the water feeding and discharging modes of the sewage treatment pond are continuous water feeding and continuous water discharging or intermittent water feeding and intermittent water discharging; controlling the hydraulic retention time of the sewage in the sewage treatment pond to be 2 to 15 days. The sewage is treated when the duckweed grow; part of the duckweed is required to be salvaged periodically in the sewage treating and duckweed growing period. According to the method disclosed by the invention, the yield of the starch and the crude protein of the duckweed can be greatly improved, and the nitrogen and the phosphorus in the sewage are removed effectively; the large-scale application of the duckweed is promoted.

Description

technical field [0001] The invention belongs to the field of aquatic plant cultivation and sewage treatment, in particular to a method for simultaneously increasing duckweed starch and crude protein yields and sewage nitrogen and phosphorus removal rates. Background technique [0002] In recent years, with the acceleration of industrialization, human society is facing a severe crisis of water pollution and resource shortage. The massive discharge of nutrients such as nitrogen and phosphorus is one of the main causes of water pollution and eutrophication, and nitrogen and phosphorus are essential nutrients for increasing the yield of biological resources. Therefore, recovering nutrients such as nitrogen and phosphorus in sewage and converting them into valuable biomass resources through phytoremediation is an effective way to simultaneously solve water pollution and resource shortage. [0003] Duckweed (Duckweed) is a general term for plants in the Lemnaceae family. There ar...

AI Technical Summary

Problems solved by technology

Cultivating duckweed in oligotrophic water body can obtain duckweed with higher starch content, but this method has the following disadvantages: (1) it is required to cultivate duckweed in oligotrophic water body. Water body is difficult to reach this requirement, and the scope of application of this method is subjected to very big limitation; (2) cultivates in oligotrophic water body, although the starch content of duckweed has been improved, the growth and output of duckweed have been seriously affected. (3) Since the oligotrophic water body does not contain nitrogen, the crude protein content of duckweed can not be increased, but will drop rapidly when duckweed is cultivated under this condition. The growth and output of duckweed are limited, and the crude protein yield of duckweed will also decline significantly; (4) cultivated under oligotrophic conditions, duckweed hardly absorbs nitrogen and phosphorus in the water body, and cannot achieve the purpose of simultaneously treating sewage

It can be seen that adopting existing methods to cultivate duckweed cannot simultaneously increase the crude protein and high starch yields of duckweed, and simultaneously achieve the effect of sewage treatment

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