I work in poultry slaughterhouse wastewater, the water used has a TDS = 20,000 and its salinity is high.
Our aeration tank consists of two series ponds that have a very low pH at the end of the first aeration. The pH is so low that the effluent also has a pH in the range of 6.5.
What is your solution to the problem?
In aeration ,some time Excess levels of DO also encourage the growth of unwanted filamentous bacteria;resulted low pH,at low temperature, The Three most important parameters in the aeration tank are pH , Temp. and Dissolved oxygen (DO), these bacteria compete with and thereby inhibit the beneficial bacteria, reducing treatment efficiency. The pH of the aeration tank should be between 6.5-8.5 to avoid stress on the microbial community and for optimal biological activity .
Proteins (meat and blood), urea, amino acid products, casein, corrosion inhibitors, process chemicals and raw materials or cleaning chemicals containing quaternary ammonium compounds. Maximum nitrification occurs at a D.O. (Dissolved Oxygen) level of 3.0 mg/l. Significant nitrification occurs at a D.O. level of 2.0 to 2.9 mg/l. Nitrification ceases at D.O. levels of
May I ask whether aeration in pond is sufficient ? It it's not adequate the pond may turn anaerobic and leads to acidification of wastewater and thus drop in pH.
Have you verified if you have Nitrification going on - this will consume Alkalinity and may lead to pH drop - Verify if NO3-N is to be found in the effluent. Is this the case you must evaluate if you are having too long SRT or to high Dissolved Oxygen level.
Another problem can be low Aeration intensity leading to accumulation of CO2. This can be verified by taking a sample out of the tank and pour the sample into a beaker with a magnetic stirrer and then measure and follow the pH the pH development during the following 1 - 2 hours. if pH increase during this time it indicates that CO2 is Stripping - In this cae you might need to increase aeration intesity to have more stripping in the process tank.
Dear Fatemeh,
I agree with Kim that nitrification is a likely cause, as it produces nitrous and nitric acids. If this is confirmed, adding alkalinity is a recommended solution. Note that each mole of nitrogen (initially in the form of organic-N or ammonium-N will produce 2 moles of acid when fully oxidized. Good luck!
- Peter