Device and method for recycling nitrogen and phosphorus in excess sludge through electrochemical sedimentation

Abstract

The invention discloses a device and a method for recycling nitrogen and phosphorus in excess sludge through electrochemical sedimentation. The device comprises an excess sludge tank, an excess sludgeanaerobic fermentation tank, a fermentation liquid sedimentation tank, an electrochemical reaction tank and a water storage tank, wherein an anode magnesium rod and a cathode carbon rod are arrangedin the electrochemical reaction tank; recycling of nitrogen and phosphorus in excess sludge is realized by forming struvite. The method for recycling nitrogen and phosphorus in excess sludge comprisesthe following steps: introducing the anaerobic fermentation liquid of the excess sludge into the electrochemical reaction tank to provide ammonia nitrogen and phosphorus, wherein electron transfer occurs to the anode magnesium rod and the cathode carbon rod under the effect of a direct current electric field and provides Mg<2+> and OH<-> respectively; recycling the struvite crystals freely settling in a conical sedimentation area; overflowing the supernate without nitrogen and phosphorus and discharging into the water storage tank. The device can realize synchronous recycling of nitrogen andphosphorus in the excess sludge without needing addition of magnesium ions, and the recycled product has noticeable economical efficiency.

Description

technical field [0001] The invention belongs to the technical field of recovery of nitrogen and phosphorus in excess sludge, and in particular relates to a device and method for electrochemical precipitation recovery of nitrogen and phosphorus in excess sludge. Background technique [0002] At present, urban sewage plants mostly use biological nitrogen and phosphorus removal technology to remove nitrogen and phosphorus. Phosphorus is an indispensable element for life activities and the leading factor causing eutrophication of water bodies. It is also a non-renewable resource, and its recycling is imperative. Biological phosphorus removal uses the action of phosphorus accumulating bacteria to transfer various forms of phosphorus in sewage to the remaining sludge, and finally realizes the reduction of effluent phosphorus concentration through sludge discharge. Essentially, it's just a shift of phosphorous, from the water phase to the mud phase. The real removal of phosphorus...

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Problems solved by technology

In this process, it is necessary to control the reaction process by monitoring the concentration of ammonia nitrogen and phosphate in the digestive liquid, and optimize the formation conditions of struvite, so as to improve the utilization rate and precipitation effect of magnesium salts. The process is cumbersome.

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