How to treat pulp-making wastewater
Thread Content
A paper mill is a place where pulp is produced, and the low-concentration water used for pulping needs to be concentrated to increase its density. However, during the evaporation and concentration process, condensed wastewater is generated; tests on this wastewater show that its COD level is 26.5 mg/l and its ammonia nitrogen level is 2.52 mg/l. However, when this water enters the biochemical system, it causes a large number of microorganisms to die. I would like to ask everyone how to pre-treat this water? Thank you!
The COD is 26.5 mg/l, and the ammonia nitrogen is 2.52 mg/l, values that are close to those of tap water. The presence of high concentrations of heavy metals may have an impact on biochemical processes; what heavy metals are present in the production process?
http://bbs.hcbbs.com/thread-1418813-1-1.html Refer to the Technical Specifications for the Treatment of Pulp and Paper Manufacturing Wastewater to see if the issue lies in too high AOX levels or water temperature.
The values you’ve provided for this condensate water – COD at 26.5 mg/L and ammonia nitrogen at 2.52 mg/L – meet the standards for Class V surface water, so it can be discharged directly. As condensate water, it should also be very clear and transparent; to understand why it can harm microorganisms, a comprehensive analysis of water quality parameters is necessary. Or other factors may cause the death of microorganisms, coinciding with the time when condensate water enters the biochemical system; related issues can be discussed on the Environmental Protection forum.
Due to the high concentration of organic matter in the intermediate water used in papermaking, physicochemical methods can be employed first to treat the wastewater and improve its quality to a certain extent, followed by biochemical methods to remove the organic substances from the wastewater. Biological treatment is an effective method for removing organic matter from papermaking wastewater, and its removal efficiency of organic pollutants depends on factors such as the pulping process, the biological treatment process chosen, and the load rate. Based on a comparative analysis of several biological methods for treating papermaking wastewater, such as biological filters and activated sludge, it was concluded that the activated sludge method yields the best results in treating papermaking wastewater. Through a comprehensive analysis of factors such as the toxicity and biodegradability of wastewater quality, as well as a comparison of various biological treatment methods, it was decided to adopt a wastewater treatment process based primarily on biological methods. Specifically, a process flow that involves prior treatment and subsequent solidification is adopted to reduce the amount of chemical agents used and thereby minimize secondary pollution. For aerobic treatment, the SBR process is used; a flocculant dosing pipe is installed at the inlet of the primary sedimentation tank. When the COD level of the incoming water is 1500 mg/L, a reaction and sedimentation process takes place, which helps to reduce the concentration in the biochemical treatment facilities and ensures their proper operation. After biochemical treatment, a small amount of flocculant is added to remove some biodegradable pollutants such as lignin, in order to ensure the quality of the effluent water
Just go and take a look at the paper mill. You could just go to South China University of Technology and ask Teacher Wan Jinquan