Method for recovering and purifying struvite from livestock and poultry manure

Abstract

The invention discloses a method for recovering and purifying struvite from livestock and poultry manure, and the method comprises the following steps: putting the livestock and poultry manure into acontinuous flow reactor, and carrying out anaerobic fermentation to obtain manure digestive juice; introducing the manure digestive juice into an electrolytic reaction stirring tan, selecting magnesium as an anode of an electrode and selecting magnesium or metal of which the activity is lower than that of magnesium as a cathode, and electrolyzing under the stirring condition of a stirrer by usinga direct-current voltage; introducing the solution after the electrolytic reaction into a sedimentation tank for static sedimentation; introducing lower turbid liquid obtained after precipitation intoa heater; filtering the heated hot solution by using a filter film; and injecting clear liquid obtained after filtration of the filter film into a condensation recovery pool, and recovering the struvite solids. The method disclosed by the invention is low in cost, short in flow, simple to control, high in production efficiency, capable of separating the struvite from impurities, and suitable forindustrial popularization.

Description

technical field [0001] The invention belongs to the field of wastewater treatment and resource recovery, in particular to a method for recovering and purifying struvite from livestock and poultry manure. Background technique [0002] Excessive nitrogen (N) and phosphorus (P) in the water body will cause eutrophication of the water body, leading to the proliferation of algae and causing pollution. Currently, ammonia nitrogen (NH 4 - N) has become the primary water pollutant in my country. Compared with other forms of nitrogen, the harm caused by ammoniacal nitrogen is more extensive, complex and long-lasting. How to remove nitrogen and phosphorus in water has always been a research hotspot. At the same time, phosphorus (P) is an indispensable element for all organisms. It is usually extracted from phosphate rock, which is a rare resource. Some studies predict that phosphate rock will reach its peak use in 2030. and run out within the next 100 years. Therefore, the develop...

AI Technical Summary

Problems solved by technology

However, in the research of recovering struvite, the way of adding magnesium salt is often adopted, and acid and alkali are also needed to adjust the pH value of the solution (8-10.5), the recovery speed is slow, and the required hydraulic retention time is long. Moreover, the technology for separating struvite is immature, which affects the economic feasibility and restricts the popularization and application of this technology.

[0005] The magnesium salts used in current research are MgCl 2 , MgSO 4 , MgO, Mg(OH) 2 , MgCO 3 etc. Most of them require a long dissolution time, and the solubility is different at the same time. However, Mg:P must always be greater than 1 to ensure the effective precipitation of struvite. Guarantees a high removal rate

However, the introduced impurity ions easily lead to side reactions, which adds difficulty to obtaining pure struvite

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