Sludge treatment method

Abstract

The invention discloses a sludge treatment method, which comprises the following steps: (1) preheating and diluting raw material sludge, and carrying out hydrothermal treatment; (2) carrying out heatexchange on the mud-water mixture subjected to hydrothermal treatment; (3) carrying out solid-liquid separation on the sludge-water mixture subjected to heat exchange to obtain sewage and thickened sludge, and carrying out low-temperature drying on the thickened sludge to obtain dried sludge and condensate; (4) carrying out anaerobic digestion on the sewage, filtering, and carrying out first quality conditioning; (5) evaporating and concentrating the sewage to obtain a sewage concentrated solution and ammonia nitrogen water obtained by condensation; and (6) performing second quality conditioning on the obtained ammonia nitrogen water by adopting phosphate and a magnesium salt, and performing solid-liquid separation to obtain a magnesium ammonium phosphate solid and filtrate. The method islow in comprehensive energy consumption, low in cost, easy in process implementation, short in treatment time, good in harmless effect, high in resource recovery rate, high in stability and high in energy utilization rate.

Description

technical field [0001] The invention relates to the technical field of environmental protection, in particular to a sludge treatment method. Background technique [0002] For the treatment of municipal sludge, anaerobic digestion, as an important treatment process, can remove organic matter in sludge and convert it into biogas for utilization, which can effectively realize the "four modernizations" of sludge. It has been widely used in European and American countries, and is also Promoted by our country. However, when the anaerobic digestion process is used for treatment, wastewater with a C / N ratio close to the same daily treatment scale will inevitably be produced simultaneously. The high ammonia concentration in this type of wastewater significantly increases the difficulty of subsequent treatment technology and production costs. At the same time, the use of conventional technology will inevitably lead to the treatment of RO concentrated water at the end of the process. ...

AI Technical Summary

Problems solved by technology

However, when the anaerobic digestion process is used for treatment, wastewater with a C / N ratio close to the same daily treatment scale will inevitably be produced simultaneously. The high ammonia concentration in this type of wastewater will significantly increase the difficulty of subsequent treatment technology and production costs.

At the same time, the use of conventional technology will inevitably lead to the treatment of RO concentrated water at the end of the process. Although some existing processes treat this part of the concentrated water, there are defects such as insufficient treatment and high costs, resulting in the inability to achieve near-zero discharge of the process. Target

[0003] At present, in the anaerobic treatment process of municipal sludge, the utilization rate of heat energy often becomes the key indicator that limits the normal and stable operation of the process. How to achieve the balance between self-produced energy and self-consumption energy is a technology that has not been properly resolved in the current process. question

In order to ensure a high removal rate and a short sludge residence time in most sludge anaerobic processes, a thermal hydrolysis device is often installed at the front end of the anaerobic process for wall-breaking treatment of sludge, but the process The energy consumption is large, and most of the heat energy cannot be effectively recycled for secondary use, resulting in a waste of energy. At present, there are also external heating media used to exchange heat for sludge. Some methods have low heat utilization rate and poor heating effect. It is not conducive to the breakdown of sludge and the release of internal pollutants, and the existing heat recovery has the disadvantage of insufficient energy recovery and utilization, which cannot achieve a good balance between self-produced energy and self-consumption energy

[0004] In the existing municipal sludge treatment process, the whole sludge is usually anaerobically treated directly. This method has the following problems: because most of the organic matter is located inside the sludge cells, the effect of breaking the wall during the digestion process is poor, and the anaerobic The removal efficiency of the overall organic matter in digestion is low, and the solid content required in the anaerobic process is low (3% to 6%), resulting in a large capacity of the anaerobic digestion tank and high infrastructure costs. In addition, the sludge in the anaerobic tank is not avoided Precipitation, high requirements for the mixing system in the anaerobic tank, and large investment in equipment

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