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In the food processing industry, wastewater from slaughterhouses and meat plants is hard to treat. It often has high organic load, lots of oil and grease, and excess ammonia and nitrogen.
During peak seasons, the flow and pollution load increase, making it harder to run the system smoothly.
This article shares a practical treatment process for slaughterhouse wastewater. It also offers tips based on real project cases to help companies meet discharge standards and lower costs.
🏭 Source and Characteristics of Slaughterhouse Wastewater
Slaughterhouse wastewater comes from steps like animal slaughter, cleaning, skinning, and meat handling.
Main features:
- High COD: Usually 2,000–8,000 mg/L from blood, grease, and proteins
- High ammonia and total nitrogen: It is caused by animal metabolites, which can easily lead to excessive ammonia nitrogen;
- Lots of oil and suspended solids (SS)
- Strong seasonal variation: Wastewater changes a lot during busy times, so the system needs a strong buffer capacity
⚙ Flowchart of the Treatment Process
To meet discharge limits, the process usually includes these steps:
1. Coarse and Fine grilles → Oil Separation Tank
- Remove big solids, hair, and grease
- Lower the load on the next steps
2. Regulation Tank + DAF Pretreatment Stage
- Regulates water volume and quality while buffering water quality fluctuations. Simultaneously removes most suspended solids and partial organic matter through chemical dosing + dissolved air flotation (DAF) system. Commonly used agents include:
- Caustic soda / sodium hydroxide: Adjust pH and enhances flocculation efficiency
- PAC (Polyaluminum chloride): Inorganic coagulant
- Cationic PAM: Reinforces suspended solids sedimentation
👉 Cationic PAM works better than anionic PAM in high-organic slaughter wastewater.
3. Biological Treatment (A/O, A2O, Contact Oxidation, or MBR)
Performs advanced removal of COD, ammonia nitrogen, and total nitrogen, serving as the core of the entire system. Common processes include:
- A/O & A2O Processes: High-efficiency nitrogen and phosphorus removal
- Contact Oxidation Method: Strong resistance to shock loads with adaptability to water quality fluctuations
- MBR (MembraneBioreactor): Produces high-quality effluent with compact footprint
📌 For better results, you can add anaerobic pre-treatment (like UASB or EGSB) to remove more organic matter.
4. Secondary Sedimentation or High-Efficiency Clarifier Tank
- Precipitate activated sludge in biochemical effluent
- PAC and PAM can be added again to improve SS and turbidity removal
5. Disinfection for Final Discharge
- Use sodium hypochlorite or chlorine dioxide
- Make sure bacteria levels meet discharge standards
6. Sludge Treatment System
- Sludge from flotation and sedimentation goes to sludge thickener
- Add cationic PAM (30%–40% charge)
- Use screw press or belt filter press for dewatering
- Make low-moisture sludge cakes for easy disposal
🔍 Common Problems and Solutions
| Problem Type | Main Issue | Suggested Fixes |
| High COD | Bio-system overloaded, weak pre-treatment | Boost DAF system and use better coagulants |
| High Ammonia/N | Weak denitrification, low carbon source | Adjust the C/N ratio, add extra carbon (e.g.,Sodium acetate) |
| High Phosphorus | No phosphorus removal | Add aluminum or iron salts to remove phosphorus |
| High SS in Effluent | Poor sedimentation , sludge loss | Add coagulants, adjust sludge reflux rate |
📌 Conclusion
Slaughterhouse wastewater has high organic load and strong seasonal changes. This means chemical selection, process design, and system control are very important.
By using a combination of pre-treatment + biological system + sludge treatment, you can:
- Keep effluent stable and within limits
- Save costs
- Support green and sustainable goals
If you face problems in slaughterhouse wastewater treatment, feel free to leave a comment or contact us. We are ready to help with professional advice.
