Common Treatment Methods of Slaughtering Wastewater
Slaughtering wastewater is generally reddish-brown with a bad smell. It contains a lot of blood, grease, wool, meat, bone, visceral impurities, undigested food, feces and other pollutants. The solid suspended matter content is high. Slaughtering wastewater has high organic matter content and good biodegradability, but high concentration organic matter is not easy to degrade and difficult to treat. The nutrients in slaughter wastewater are mainly nitrogen and phosphorus, in which nitrogen mainly exists in the form of organic matter or ammonium salt, while phosphorus mainly exists in the form of phosphate.
The coagulants commonly used in coagulation treatment are aluminium salts, ferric salts and so on. Polyferric sulfate coagulation has a better effect on Slaughter Wastewater treatment. In order to reduce the use of aluminium salts, polyaluminium chloride and polyvinylammonium ammonium chloride can be used as coagulants in the synthesis of Polyferric sulfate, adding any proportion of aluminium salts and certain proportion of silicates, and a small amount of polyacrylamide to produce a new coagulant. The composite inorganic macromolecule coagulant has a wide range of values and temperature application. It can be used as a coagulant to treat slaughter wastewater. The removal rate of chroma can reach the level of simple coagulation treatment. There is an obvious problem that the blood water produced in slaughter process is difficult to remove, and a large number of sludge and waste residue are produced at the same time (so slaughter wastewater should be treated before using coagulant). Appropriate denaturation treatment, followed by ferrous sulfate and calcium oxide composite coagulant treatment, has a better treatment effect. Coagulation process has low cost and good treatment effect at low temperature. It is mostly used to treat low concentration wastewater or pretreat high concentration wastewater in order to reduce the load of subsequent biological treatment.
(2) SBR method
SBR treatment of slaughterhouse wastewater is a more economical and effective method. However, because slaughterhouse wastewater contains a lot of grease, blood water, carbon and nitrogen ratio and carbon and phosphorus ratio are large, and nitrogen and phosphorus are relatively insufficient. At this time, oily foam is prone to cause sludge to loose and exponentially increase, which is prone to high viscosity expansion, resulting in sludge loss. In order to achieve high denitrification effect, the SBR process must be equipped with a stirring device, and the phenomenon of sludge floating is unavoidable. The removal effect of chroma is not ideal, and the post-treatment process must be supplemented. Therefore, the air flotation degreasing process becomes the necessary treatment unit for the treatment of slaughter wastewater by SBR process. After SBR treatment, the ammonia nitrogen content of wastewater is still very high, which can be removed by chemical method after this process if necessary.
(3) Sequential batch biofilm process
Sequence batch biofilm process has good denitrification and denitrification function, good hydraulic conditions, strong impact load, high biological concentration, and can be suitable for the growth of digestive bacteria for a long generation (under the same operating conditions, the treatment effect of biofilm system is better than that of activated sludge system).
(4) Aerobic biological treatment
Aerobic biological treatment of organic wastewater requires sufficient oxygen supply, but the traditional oxygen supply method can not meet the oxygen demand of high concentration organic wastewater. It has the advantages of fast reaction speed, small area, low capital construction cost, convenient operation and management, and stable effluent quality.
(5) Anaerobic biological treatment
Anaerobic biological treatment is mainly used to treat high concentration organic wastewater. Many improved anaerobic methods are used in the treatment of slaughter wastewater, aiming at the characteristics of various treatment processes of slaughter wastewater.
(6) Pressurized Biological Contact Oxidation-Coagulation-Precipitation Combined Process
This process is suitable for the treatment of medium concentration slaughter wastewater. The effluent was treated by pressurized biological contact oxidation to increase the degradation rate of dissolved oxygen and organic matter in wastewater, and then coagulated and precipitated to reach the secondary discharge of existing enterprises.
(7) Two-stage high-speed up-flow anaerobic sludge bed UASB method and dissolved air flotation-up-flow anaerobic sludge bed method
This process is an improvement of single UASB process. It is suitable for treating slaughter wastewater containing high concentration suspended solid fat particles and grease. The first stage of two-stage high-speed up-flow anaerobic sludge bed UASB process is UASB reactor using flocculant sludge, which can remove insoluble COD such as fat particles and grease. The second stage is COD using granular sludge.
(8) Hydrolysis acidification-biosorption regeneration-contact oxidation process
This process is especially suitable for the treatment of high concentration slaughter wastewater and wastewater with great changes in water quality and quantity. Using AB two-stage combination process, sludge flocs in stage A have high load, strong adsorption capacity and good sedimentation performance, strong impact load resistance, and have a great buffer effect on toxic substances, but the sludge volume is high, so appropriate sludge treatment measures should be taken. A small amount of falling biofilm in the effluent of the secondary clarifier in Section B was further removed by air flotation treatment to improve the effluent.
(9) Upflow Anaerobic Sludge Bed Filter-Sequence Batch Activated Sludge Process
The process is suitable for wastewater treatment with high protein content and fluctuating water quality. The upflow anaerobic sludge filter is a reactor which combines the upflow anaerobic sludge bed filter with the upflow anaerobic sludge bed filter, the sequencing batch activated sludge method and the anaerobic filter. The process is suitable for slaughterhouse wastewater with intermittent feed water.