I’ve just taken on a new project; I’d appreciate everyone’s advice
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The day before yesterday, I went to a meat processing plant; they showed us the production facilities there. The main issue there is wastewater resulting from thawing process, which contains blood, oil, meat residues, and a large amount of suspended solids. At present, they only have oil separation measures in place. Samples were taken from the water exiting their oil separation tanks, and laboratory analysis revealed a pH value of 5.45, a COD level of 14,510 mg/L, and an ammonia nitrogen level of 214 mg/L; other parameters were not measured. The process I initially selected is air flotation + UASB + A2O, as the COD level is high; therefore, UASB is used. Considering phosphorus and nitrogen removal, A2O is added later. It is required to meet the third-level emission standards, with COD below 500. Ammonia nitrogen is less than 40. Everyone, please help me check if this process is feasible Or if you think there is a better manufacturing process, please give me some advice. I’m extremely grateful.
It depends on the pH level in the water; at a pH of 8, a concentration of around 1000 mg/l results in an unpleasant odor, while at 300 mg/l, no such odor is noticeable. The pungent gas is ammonia that volatilizes; ammonia tends to volatilize in its free state only at high pH levels.
If it’s about design, you currently have limited data available, and it still needs to be verified whether that data is representative. It is recommended to take samples in accordance with the requirements for water sample collection, to ensure that the raw water is representative ； Conduct a comprehensive analysis of the raw water, and select the process route based on the data ； The laboratory conducts pilot tests to select and verify the feasibility of the process scheme.
Preparatory work for design is essential; acting blindly based on experience can lead to significant risks.
Oil stains, meat residues, and suspended solids – if air flotation is used, the loading on the air flotation system is high, more chemicals are required, and there is also more sludge. It is recommended to consider the pretreatment process: fine screen—oil separation—air flotation—hydrolysis acidification—UASB.
This post was last edited by man00man on 2016-6-13 at 13:40. Mechanical grids are necessary for air flotation; oil removal and slag separation serve as pre-treatment steps. However, USAB remains somewhat dangerous, so it’s best to conduct pilot and scale-up tests first
The test parameters provided by the poster are a bit limited; if detailed design of the process parameters is desired, it would be best to determine the organic nitrogen level, which facilitates the analysis of the residence time in the nitrification stage. Additionally, it is necessary to determine how much oil remains in the water after oil separation, and whether it is required to add demulsifiers or coagulants – this also requires a detailed analysis. Also, if the goal is to keep the COD below 500 when the water is discharged, it will be difficult to meet the requirements regarding ammonia nitrogen; on the other hand, if the ammonia nitrogen levels are within the acceptable range, the COD concentration will be lower.