Pre-treatment method used for increasing residual activated sludge anaerobic fermentation hydrogen production efficiency

Abstract

The invention discloses a pre-treatment method used for increasing residual activated sludge anaerobic fermentation hydrogen production efficiency. The pre-treatment method comprises following specific steps: municipal sewage plant secondary sedimentation tank sludge is taken as a fermentation base material, ammonium chloride is added into the fermentation base material, fermentation system pH value is adjusted, at a constant temperature, a certain free ammonia (FA) concentration is achieved for 12h of pre-treatment, and anaerobic fermentation is carried out for hydrogen production. The free ammonia based pre-treatment is capable of promoting dissolving out of organic matters in sludge, fully inhibiting the activity of hydrogen-consuming microorganisms such as acetogenic bacteria and methanogens of the same type, and increasing hydrogen production efficiency greatly. The free ammonia pretreatment hydrogen production rate is as high as 14.65ml H2 / g VSS, and is 14.22 times of that of a blank group, and is 2.41 times of that of an alkalescence pretreatment group (pH is 9.0+ / -0.1). The pre-treatment method is simple in operation and high in hydrogen production efficiency; adding of additional special bacterial strains as hydrogenogens is not necessary; cost is low; sludge quantitative reduction, resource recycling, and stabilization can be realized at the same time; and important environmental protection ecological meaning is achieved.

Description

technical field [0001] The invention mainly relates to the technical fields of environmental protection and solid waste recycling, and in particular relates to a method for using free ammonia to pretreat excess activated sludge to improve its anaerobic fermentation hydrogen production efficiency. technical background [0002] At present, as more and more sewage treatment plants are put into use, a large amount of excess sludge is produced as its main by-product. For example, in 2015, the output of excess activated sludge in my country can reach 34 million tons (with a solid content of about 20% ). However, the treatment and disposal of sludge is expensive, which can account for 60% of the treatment cost of sewage treatment plants. The remaining sludge contains 50-70% organic substances (such as polysaccharides, proteins, and lipids), which are ideal recyclable substances. However, these residual sludges are generally only dehydrated and then disposed of by landfill or incin...

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Problems solved by technology

[0004] 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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