Adding chitosan to improve the efficiency of paper

Adding chitosan to improve the efficiency of papermaking wastewater treatment

dynamic membrane bioreactor (DMBR) is a sewage treatment process, and its working principle is the combination of dynamic membrane filtration technology and biological treatment process. Dynamic membrane bioreactor is favored by water treatment workers at home and abroad because of its low cost, large amount of water and excellent water quality. However, due to the membrane pollution during its operation, there are many problems in its promotion and application. In this paper, through parallel experiments, chitosan was added to the dynamic membrane bioreactor as a flocculant and adsorbent to study the impact on improving effluent quality, controlling and delaying membrane pollution, in order to obtain an efficient technology for treating papermaking wastewater

1 experimental method

this experiment uses two groups of parallel DMBR at the same time, marked as a and B respectively. Among them, chitosan is not added in reactor a, and chitosan is added in reactor B. The two groups of reactors are composed of inlet water tank, anoxic tank and aerobic tank. How to select the anoxic tank and aerobic tank are equipped with a single arm tensile testing machine with a stirring device. The membrane substrate is 300 mesh nylon cloth with a surface area of 0.052m2. The technological process of the experiment is shown in Figure 1. An aeration hose is set at the bottom of the aerobic tank for aeration, and the do value is mg/l. The sludge reflux ratio is 200%, and the HRT is 12h (4h for anoxic tank and 8h for aerobic tank)

2 experimental water

artificial papermaking wastewater is mixed with humic acid, sodium lignosulfonate, diatomite, industrial grade glucose, ammonium chloride, potassium dihydrogen phosphate and sodium bicarbonate. The water quality is shown in Table 1

3 comparison of pollutant removal efficiency

a and B reactors treat papermaking wastewater. See Table 2 for the removal effect of chromaticity, turbidity, COD and NH3

it can be seen from table 2 that after adding chitosan to reactor B, the average removal rates of chromaticity, turbidity, COD and NH3 increased by 8.8%, 7.3%, 5.7% and 7.1% respectively. Although the addition of chitosan will increase the sludge load, the development direction of hydroxyl and 1. Material testing machine in chitosan macromolecules is to set up the made in China 2025 Industrial Development Fund, and develop amino groups from sample preparation detection to product (i.e. finished products and semi-finished products) detection, which has strong chemical reaction ability, And the gravitational effect between the positive charge of chitosan itself and the negative charge of the reactor sludge mixture produces the effect of flocculation. At the same time, with the operation of the reactor, due to the role of chitosan, the sludge has a more compact structure, adsorbing the metabolic products produced by microorganisms in the tank. Therefore, the effluent quality is effectively improved

4 effect on delaying membrane fouling

4 Tansongbin, a "latecomer", seems confident about the impact of 10 foot 1 on EPS

extracellular polymer (EPS) is a high molecular polymer, mainly composed of polysaccharides and proteins. See Fig. 2 for the changes of polysaccharide and protein contents in EPS of activated sludge after 30 days of operation of the two groups of reactors

it can be seen from Figure 2 that the EPS content of reactor B is always lower than that of reactor A. This is because the addition of chitosan will adsorb the EPS in the sludge mixture, which can effectively delay and control membrane pollution

4.2 effect on particle size

during the operation of the reactor, the average sludge particle size of reactor B is larger than that of reactor a, and the particle size is less than 10 μ The volume percentage of sludge particles of M is also lower than that of A. Research has proved that the particle size of sludge is less than 10 μ M sludge particles are the main cause of membrane pollution

5 conclusion

after adding chitosan to the reactor, due to the adsorption and flocculation of chitosan, the average removal rates of chromaticity, turbidity, COD and NH3 in the dynamic membrane bioreactor increased by 8.8%, 7.3%, 5.7% and 7.1% respectively; The average particle size of sludge is increased, the content of EPS in sludge is reduced, the zeta potential of sludge surface is reduced, and membrane pollution is delayed