Different Methods for Treating Phosphorus Containing Wastewater in Science Popularization

The treatment of phosphorus containing wastewater mainly comes from industrial raw materials, various detergents, pesticides, fertilizers, and human domestic sewage. At present, the commonly used methods for treating phosphorus containing wastewater at home and abroad can be generally divided into chemical methods, biological methods, adsorption methods, crystallization methods, etc.

1. Chemical method

The principle of chemical phosphorus removal is to add chemical agents to phosphorus containing wastewater, and the reagents react chemically with phosphate ions in the wastewater to generate insoluble phosphate precipitates. Through filtration, the phosphate precipitates are removed to achieve the purpose of phosphorus removal. Chemical reagents are mainly divalent or trivalent metal ions.

At present, the world widely emphasizes the need for large-scale control of phosphorus content in water environments. So far, chemical precipitation is still a practical and effective method for phosphorus removal from wastewater. The chemical method has simple operation, stable phosphorus removal effect, and a treatment efficiency of over 80%. When the concentration of phosphorus in the wastewater is high or fluctuates to some extent, it can still maintain a good phosphorus removal effect. However, the amount of medication used is large, resulting in high treatment costs for phosphorus containing wastewater and the production of a large amount of difficult to treat high phosphorus sludge.

2 Biological methods

Biological phosphorus removal is mainly accomplished by a group of microorganisms collectively known as polyphosphate accumulating bacteria. Due to their ability to assimilate fermentation products in an anaerobic state, polyphosphate accumulating bacteria have a competitive advantage in biological phosphorus removal systems. In anaerobic conditions (without the presence of dissolved oxygen and nitrate nitrogen), facultative bacteria convert dissolved organic matter into volatile fatty acids; Polyphosphate accumulating bacteria hydrolyze intracellular phosphorus into orthophosphate and obtain energy from it, absorbing easily degradable COD in wastewater and assimilating it into intracellular carbon energy storage substances such as poly - β - hydroxybutyric acid or β - hydroxyvaleric acid. Under aerobic or anaerobic conditions, polyphosphate accumulating bacteria use molecular oxygen or combined oxygen as electron acceptors to oxidize and metabolize stored substances such as PHB or PHV, and generate energy. They excessively take up phosphate from wastewater, which is stored in the form of high-energy substance ATP. Some of the energy is converted into polyphosphate and stored inside the cell as energy, achieving efficient biological phosphorus removal through the discharge of residual sludge. However, microorganisms have strict requirements for the surrounding living environment and are sensitive to changes in water quality.

3 adsorption method

The principle of phosphorus removal by adsorption method is that certain porous or high specific surface area solid substances have adsorption affinity for phosphate ions in water, and remove phosphorus from wastewater through adsorption affinity. The selection of phosphorus adsorbents requires meeting the following conditions: (1) high adsorption capacity; (2) High selectivity; (3) Fast adsorption speed; (4) Strong resistance to interference from other ions; (5) No harmful substances dissolved out; (6) Easy regeneration and stable performance of adsorbents; (7) The raw materials are easy to obtain and the cost is low.

Adsorption method for phosphorus removal does not require the addition of chemical reagents, is simple and flexible to operate, does not produce secondary pollution, and has a good effect on solute separation in dilute solutions. It is suitable for treating low concentration phosphorus containing wastewater. There are already some experimental results of highly efficient adsorbents with excellent adsorption capacity. From the trend, the research on highly efficient synthetic adsorbents will be an important development direction for wastewater phosphorus removal adsorbents.

4 Crystallization method

The principle of phosphorus removal by crystallization method is that after adding reagents to phosphorus containing wastewater, the metastable state of ions in the solution is affected, and phosphate ions precipitate on the surface of crystal seeds in the form of phosphate. The purpose of phosphorus removal is achieved through solid-liquid separation technology.

Haipu customized phosphorus containing wastewater treatment process

Jiangsu Haipu Functional Materials Co., Ltd. is committed to the research and industrialization of high-performance adsorbents and catalysts. In 2018, it was approved as the Suzhou Adsorption and Catalytic Functional Nanomaterials Engineering Technology Research Center. Through years of independent research and development, it has achieved international leading levels in ion exchange technology and adsorption technology, nano inorganic material hybridization technology, etc., realizing the serialization of adsorption and catalytic products and successfully applying them in the fields of environmental protection and resource recycling. With a series of independently developed high-performance adsorbents and catalysts as the core, combined with self-developed process technology, Haipu has become a professional supplier of green and environmental protection solutions.

The special adsorption material researched by Haipu Company can selectively adsorb phosphorus in wastewater, achieving efficient adsorption and thorough desorption of phosphorus. The phosphorus content in the desorbed wastewater is greatly reduced, and it can generally be directly sent to the biochemical system to meet the discharge standards after biochemical treatment. When using Haipu's adsorption process to treat phosphorus containing wastewater, the wastewater is pre filtered to remove suspended and particulate matter, and then enters the adsorption tower for adsorption. The special adsorption material filled in the adsorption tower can adsorb the phosphorus in the wastewater on the surface of the material. After adsorption saturation, a specific desorption agent is used to desorb the adsorption material, so that the adsorption material can be regenerated, and this process is continuously repeated. The process flow of wastewater adsorption treatment is shown in the above figure.

Case Introduction

This newly built phosphorus containing wastewater adsorption treatment facility has a total designed wastewater treatment capacity of 100m 3/d. The high phosphorus content in the wastewater affects the stable production of the enterprise. Haipu has customized the process design for the wastewater, and the wastewater design indicators are shown in the table below.

Case 1 Adsorption of inlet and outlet water data

Haipu's customized adsorption process can deeply adsorb and remove phosphorus content from wastewater, with a stable phosphorus removal rate of over 99%. The adsorbed water phosphorus content meets customer requirements (<10mg/L), while not producing secondary pollution, ensuring the normal operation of the enterprise.

This newly built phosphorus containing wastewater adsorption treatment facility has a total designed wastewater treatment capacity of 200m3/d. The wastewater has a high phosphorus content, which cannot meet the production needs of the enterprise. Haipu's customized adsorption process can deeply adsorb and remove phosphorus content from wastewater, with a stable phosphorus removal rate of over 95%, and the adsorbed water phosphorus content meets customer requirements (<1mg/L).

Case 2 Adsorption of inlet and outlet water data

Advantages of adsorption method

1. Efficiently remove phosphorus from wastewater with high removal efficiency, which can be used for pre-treatment of wastewater before biochemical treatment or end control after biochemical treatment;

2. Low investment, low operating costs, and small footprint;

3. High degree of automation and simple operation;

4. Mature and leading technology, with no secondary pollution.