How to eliminate the influence of chloride ions?
1. Domestication of activated sludge
By gradually increasing the chloride ion content in the biochemical influent, the microorganisms will balance the osmotic pressure in the cell or protect the protoplasm in the cell through its own osmotic pressure regulation mechanism. These regulation mechanisms include the aggregation of low molecular weight substances to form a new extracellular protective layer, It modulates its own metabolic pathways, alters its genetic makeup, etc.
Therefore, normal activated sludge can treat high chloride ion wastewater by domestication within a certain chloride ion concentration range for a certain period of time. Although activated sludge can improve the chloride ion tolerance range of the system and improve the treatment efficiency of the system through domestication, the domestication of activated sludge Microbes in mud have a limited tolerance to chloride ions and are sensitive to changes in the environment. When the chloride ion environment changes suddenly, the adaptability of microorganisms will disappear immediately. Domestication is only a temporary physiological adjustment of microorganisms to adapt to the environment, and has no genetic characteristics. This adaptive sensitivity is very detrimental to sewage treatment. The domestication time of activated sludge is generally 7-10d. Domestication can improve the tolerance of sludge microorganisms to salt concentration. The reduction of activated sludge concentration in the initial stage of domestication is due to the increase of salt solution. The performance is negative growth, and the microorganisms that have adapted to the environment begin to multiply in the later period of domestication, so the concentration of activated sludge increases. Taking the removal of COD by activated sludge in 1.5% and 2.5% sodium chloride solution as an example, the COD removal rates in the early and late stages of domestication were 60%, 80% and 40%, 60%, respectively.
2. Dilute wastewater with high chloride ion concentration
In order to reduce the concentration of chloride ions in the biochemical system, the influent water can be diluted so that the chloride ions are lower than the toxic threshold, and the biological treatment will not be inhibited. Its advantages are simple method, easy operation and management; disadvantages are increased processing scale, capital investment and operating costs. For sewage plants, due to the large amount of water inflow and continuous operation, even if the chloride ion concentration is high at a certain time measured by online instruments, the operability of targeted dilution is poor. Therefore, this method is more suitable for factories and enterprises that produce wastewater with high chloride ion concentration.
3. Select a reasonable process flow
Different treatment processes are selected for different concentrations of chloride ion content, and the anaerobic process flow is appropriately selected to reduce the tolerance range of chloride ion concentration in the subsequent aerobic section.
4. Improve biochemical system DO
Properly increase the dissolved oxygen in the biochemical system to ensure the activity of activated sludge.
5. Discharge excess sludge
Increase the discharge of excess activated sludge to ensure that the sludge grows in the logarithmic growth phase to improve the removal efficiency of pollutants.
6. Add nutrient source
While increasing dissolved oxygen, the metabolism of sludge is accelerated. In order to ensure the metabolism of the sludge, it is necessary to ensure the adequacy of nutrients. If necessary, a certain nutrient source can be appropriately added to ensure the activity of the sludge.
