Method for recycling phosphorus from urban sludge anaerobic digestive fluid by utilizing dolomite

Abstract

The invention discloses a method for recycling phosphorus from an urban sludge anaerobic digestive fluid by utilizing dolomite. The method comprises the following steps of: mixing dolomite particles with the filtered anaerobic digestive fluid to obtain a digestive fluid rich in calcium and magnesium ions under the condition that the pH value is 4.0-4.5, filtering the digestive fluid and then reacting and carrying out primary phosphorus recycling under the condition that the pH value is 8.0-10.0 to obtain a recycling product which mainly comprises calcium orthophosphate and a supernatant; and adding the supernatant serving as a calcium magnesium source after the primary phosphorus recycling into the pretreated anserobic digestive fluid with the pH value of 4.0-4.5 in mol ratio of (0.10-0.70):1, and reacting to obtain a secondary recycling product containing calcium orthophosphate and magnesium ammonium phosphate under the condition that the pH value is 8.5-10.0. In the invention, the dolomite is taken as the calcium magnesium source, and phosphorus in the urban sludge anserobic digestive fluid is recycled through two steps; and meanwhile, partial nitrogen is recycled, the phosphorus recovery rate is high, the phosphorus content of the product is high, the chemical cost is low, and an economic and effective method is provided for sustainable utilization of phosphorus resources.

Description

technical field [0001] The invention belongs to the technical field of municipal sludge resource utilization, and relates to a method for recovering phosphorus in urban sludge anaerobic digestion solution, in particular to a method for recovering phosphorus from urban sludge anaerobic digestion solution by using dolomite to provide calcium and magnesium sources by precipitation resource method. Background technique [0002] Phosphorus is an indispensable nutrient element for life forms. From the perspective of its natural cycle process, phosphorus is a non-renewable and irreplaceable resource. In my country, phosphate-rich rock can only be used for 10-15 years, and the Ministry of Land and Resources has listed phosphate rock as one of the 20 types of minerals that cannot meet the needs of national economic development after 2010. At the same time, phosphorus is one of the main factors causing water eutrophication. With the improvement of people's living standards, the nutr...

AI Technical Summary

Problems solved by technology

[0006] In summary, the above phosphorus recovery methods mainly have the following problems: (1) Adding calcium salt or magnesium salt and calcium and magnesium oxide or hydroxide to recover phosphorus-rich clear liquid in the form of ammonium magnesium phosphate or calcium phosphate salt Phosphorus in the anaerobic digestion solution, the cost of the agent is higher; use industrial waste such as fly ash leachate to provide a calcium source to recover phosphorus in the anaerobic digestion solution, and nitrogen in the anaerobic digestion solution has not been recovered; (2) use seawater as a magnesium source to recover phosphorus at the same time and nitrogen, if no chemical agents are added, the phosphorus recovery rate of the phosphorus-rich clear liquid is not high; if ammonium chloride is added, the cost of phosphorus recovery agents is increased; (3) the induced crystallization method recovers the phosphorus in the rich phosphorus clear liquid Phosphorus, the recovery rate of phosphorus is low, and the phosphorus content of the recovered product is low

Images