A pretreatment method for improving the hydrogen production efficiency of anaerobic fermentation of excess activated sludge

Abstract

The invention discloses a pretreatment method for improving the hydrogen production efficiency of excess activated sludge by anaerobic fermentation. The specific methods include: using the sludge from the secondary sedimentation tank of the urban sewage treatment plant as the fermentation substrate; adding ammonium chloride to the fermentation substrate; adjusting the pH of the fermentation system, and making it reach a certain concentration of free ammonia (FA) at a constant temperature for fermentation. Pretreatment for 12 hours, followed by anaerobic fermentation for hydrogen production. The invention is based on the principle that the free ammonia pretreatment not only promotes the dissolution of organic matter in the sludge, but also fully inhibits the activity of hydrogen-consuming microorganisms such as homoacetogenic bacteria and methanogenic bacteria, thereby greatly improving the hydrogen production efficiency. In the present invention, the hydrogen production rate of free ammonia pretreatment can reach 14.65mL H 2 / g VSS, 14.22 times that of the blank group, and 2.41 times that of the alkaline pretreatment (pH=9.0±0.1). The method provided by the invention is simple in operation, highly efficient in hydrogen production, does not need additional special strains as hydrogen-producing bacteria, is cheap, and can realize sludge reduction, resource utilization and stabilization at the same time, and has important environmental protection and ecological significance.

Description

Technical field [0001] The present invention relates to solid waste and environmental resources and technology, and in particular relates to a method for using activated sludge residual free ammonia pretreatment to improve the efficiency of anaerobic fermentation hydrogen. [0002] technical background [0003] Currently, as more and more sewage treatment plant in use, as its main byproduct sludge generated in a large number, e.g., 2015, the yield of activated sludge up to 34 million tons (about 20% solid content ). And the cost of treatment and disposal of sludge is expensive, it may occupy 60% of the cost of the sewage treatment plant. Sludge containing 50 to 70% of organic material (such as a polysaccharide protein, lipid species), available resources are ideal substance. However, in general these dehydrated sludge only, on the use of landfill or incineration process, in which organic waste has not been effectively utilized. In addition, the whole process is costly, but also oc...

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Problems solved by technology

[0005] In the existing sludge hydrogen production technology, the current research mainly focuses on the inoculation of bacteria and pretreatment (such as ultrasonic, ozone, heat treatment and acid-base treatment) to improve hydrogen production, such as pure hydrogen production by adding and cultivating bacteria (Clostridium bifermentans) or enrichment of hydrogen-producing bacteria to increase hydrogen production; reports (International Journal of Hydrogen Energy, 2013, 38:7246-7252) after photocatalytic pretreatment of excess sludge, at 55 ° C high temperature, initial pH Hydrogen production by anaerobic fermentation under the condition of 7.6 can increase the hydrogen production of excess activated sludge by anaerobic fermentation; the patent No. ZL200310116142.6 discloses "A method for hydrogen production by anaerobic fermentation of excess sludge from sewage plants and device", which adjusts the pH to 12-13, uses strong alkali to pretreat sludge, inhibits methane bacteria and produces hydrogen; patent No. 200510066428.7 discloses a "heat treatment for producing hydrogen from waste sludge from sewage treatment plants - Fermentative hydrogen production method", the fermentation conditions are 121°C, 1.5kPa, 0.5h pretreatment; however, there are inevitable disadvantages in the above method, such as inoculation of special hydrogen-producing bacteria, long period of culturing hydrogen-producing bacteria, special bacteria The addition of species will increase the cost of the hydrogen production process. At the same time, the separation process of special strains is complicated, and it needs to be purified and identified. Improper treatment will affect the hydrogen production effect and reduce the hydrogen production rate; The production of hydrogen microorganisms such as methanogens and homoacetogens is vigorous, which is not conducive to the accumulation of hydrogen; the over-strong alkaline environment is very unfavorable to the subsequent biological treatment of sludge, and the landfill of excess sludge is more harmful to the soil than the original sludge. Large; high temperature and high pressure or photocatalytic treatment has a long delay time (from the start of fermentation to hydrogen production), the purity of hydrogen is low, and the power consumption is large, which requires high equipment manufacturing and increases production costs

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