Research Of The COD Degradation Efficiency Of Navicula In Papermaking Wastewater And Its Influencing Factors

In China, papermaking wastewater is a major source of surface water pollution, which accounts for the discharge of industrial wastewater COD emission of 35.3%, ranking first in the country. So far, a variety of methods are used in COD treatment of papermaking wastewater, including physical, chemical and biological methods. But there have some problems such as the high cost, complicated operations, imperfect post-processing and leading to secondary pollution and other issues, the algae treatment to papermaking wastewater method is simple and low cost. Based on this, in this study, Navicula is selected as the treatment of COD in papermaking wastewater. The results show that in four different concentrations of papermaking wastewater, the growth curve of Navicula has no significant difference, and 3 days later, the biomass difference of Navicula in different wastewater concentration gradient is small. With the prior relevant study, we infer that the lignin in papermaking wastewater may inhibit the algal growth. The addition of Si element takes a certain extent effect on the growth of Navicula and the COD removal efficiency of papermaking wastewater, and the best-fit amount of Si element added to the wastewater is 100 times of original concentration.We use sodium lignosulphonate to make domestication on Navicula to produce a certain tolerance and then to process the papermaking wastewater to improve the degradation of COD in papermaking wastewater. Domestication results show that the most suitable concentration of Navicula is 0.06g sodium lignosulphonate/100mL DIM. Before and after the domestication, the degradations of COD in papermaking wastewater using Navicula are 55.10% and 61.93%, the disparity is 6.83%. This shows that the capacity for the degradation of COD in papermaking wastewater of Navicula after domestication is better than before.D1 Medium composition has certain impact on the growth of not been domesticated Navicula but not the domesticated Navicula in the papermaking wastewater. Moreover, different nutrients of D1 Medium are working together to stimulate the growth of algae, rather than one particular class of substances. But according to the growth curve of Navicula, there will be better growth of Navicula if the more comprehensive nutrients. In addition, the degradation results of COD show that the addition of nutrients can help Navicula degradation of COD in papermaking wastewater. When using the domesticated Navicula handling high concentrations of COD in papermaking wastewater, the capacity is lower than handling low concentrations of COD, but still has a certain effect.