Professor of NTU: Patented technology to overcome the difficult problem of metal salt coagulation treatment


1. Introduction

In view of the problems existing in the current metal salt coagulation treatment, including slow floc growth rate, small floc size, long sedimentation time, and high residual metal concentration, the research group of Professor Zhang Shujuan from the School of Environment of Nanjing University conducted an in-depth analysis of titanium coagulation. The hydrolysis characteristics and coagulation mechanism of the agent, using a simple sol-gel method, obtained a new type of titanium gel coagulant (TXC) with independent intellectual property rights, and has been authorized 1 US invention patent and 2 Chinese national invention patents .

TXC has the following characteristics:

1) The growth rate of flocs is 10-30 times that of iron/aluminum salt, and the size and sedimentation rate of flocs are 3-10 times that of iron/aluminum salt;

2) The applicable pH range is wide, and the coagulation performance is less affected by temperature and turbidity;

3) The hydrolysate has a high concentration of surface sites and has a good removal effect on heavy metals such as As(III) and Sb(III);

4) The storage liquid is weakly acidic, and the pH changes little after coagulation, especially suitable for the treatment of low alkalinity water;

5) Low residual metal concentration in coagulation effluent, suitable for pre-treatment of membrane;

6) The coagulated sludge can be used as resources after treatment.

2. Application description

Since 2016, through unremitting efforts, Professor Zhang Shujuan's research group has initially achieved mass production of TXC from the laboratory to practical applications, and is currently cooperating with related companies in the titanium industry. Considering the advantages of TXC, we have successively carried out application evaluation studies on low temperature and low turbidity water (Figure 1), algae-containing water (Figure 2), and printing and dyeing wastewater (Figure 3). A breakthrough has been made in processing. Currently, we are cooperating with relevant companies in the field of water treatment chemicals to conduct research on the application of TXC in water reuse.

3. Benefit analysis

Economic benefits: TXC is far superior to traditional coagulants in application scenarios such as low temperature and low turbidity water, algae-containing water, printing and dyeing wastewater, and low TXC dosage required to meet discharge standards; combined use can solve the dilemma of traditional coagulation and significantly Reduce the dosage of traditional coagulants; in addition, the application of TXC can greatly reduce the consumption of alkali; the use of TXC in the coagulation-membrane filtration combined process can extend the service life of the membrane and save maintenance costs; TXC coagulated sludge can be recycled for production Value-added TiO2 and other products. The quantification of economic benefits requires specific analysis based on specific conditions. 

Environmental benefits: TXC coagulation effluent has low residual metal concentration and has little environmental impact on the receiving water; the recycling of titanium coagulated sludge can reduce the land load and potential secondary pollution caused by sludge landfill. 

4. Ways of Cooperation

Technology transfer or cooperative development. 

5. Industry sector

Environmental functional materials, reclaimed water reuse, surface water purification, drinking water treatment, domestic sewage treatment, wastewater treatment.