CN103663890B - A method of adding NaCl to strengthen the acid production of residual sludge alkaline fermentation - Google Patents

Abstract

A method for reinforcing the acid production amount of residual sludge alkaline fermentation through adding NaCl belongs to the technology field of activated sludge decrement and anaerobic fermentation for providing an internal carbon source. The method comprises the following steps: introducing residual sludge into an SBR reactor, slowly successively pumping a NaCl-containing solution and an alkali-containing solution from two sides of the bottom of the device, and at the same time, starting a stirrer. Culture conditions comprise that the temperature is 20 to 30 DEG C, the pH is 8 to 10, and the ORP is -100 to -150 mv. The acid production amount of volatile fatty acid can be stably prolonged for a certain time. The method further improves the acid production amount under the residual sludge alkaline fermentation condition, and at the same time, solves the problem of short stable time of acid production of residual sludge fermentation.

Description

A method of adding NaCl to strengthen the acid production of residual sludge alkaline fermentation

technical field

The invention relates to a method for enhancing acid production by alkaline fermentation of excess sludge, and belongs to the technical field of activated sludge reduction and anaerobic fermentation providing internal carbon source. Through the joint action of hydrolytic acidification bacteria and sea salt bacteria, the amount of acid produced by hydrolysis and fermentation of excess sludge is increased, the stability time of acid production is prolonged, and the sludge volume is reduced at the same time.

Background technique

Activated sludge method is a common way to treat wastewater at present, but the sewage treatment plants using activated sludge treatment process generally have the problem of insufficient carbon source, which seriously restricts the operation effect of sewage treatment plants.

Generally, there are two ways to solve the problem of insufficient carbon sources in sewage treatment plants:

Method 1: Adding external carbon sources, generally methanol, ethanol, and acetic acid, this method solves the problem of insufficient carbon sources in sewage treatment plants to a certain extent, and improves the operation effect of sewage treatment plants, but long-term dosing increases running costs.

Method 2: Use surplus sludge hydrolysis acidification to provide internal carbon source. This method fundamentally solves the problem of insufficient carbon source in sewage treatment plants, and at the same time solves the problem of surplus sludge treatment.

Simple sludge hydrolysis and acidification not only has low yield of volatile fatty acids, but also is unstable. In response to this problem, experts at home and abroad have carried out certain pretreatment on excess sludge before fermentation. Experiments have proved that under alkaline conditions, the dissolution rate of organic matter in excess sludge can be greatly improved and the sludge fermentation time can be shortened. However, alkaline fermentation There is also the problem of short fermentation stability time of excess sludge and limited dissolution of volatile fatty acids. If continuous use is desired, fresh sludge must be continuously and regularly input to remove fermentation sludge.

Using the salinity method to alkaline ferment excess sludge, in the case of one-time addition of excess sludge for fermentation, it can not only increase the yield of volatile fatty acids in sludge fermentation, but also prolong the stable time of acid production; if regular input is adopted Adding fresh sludge and removing fermented sludge can also greatly increase the production of volatile fatty acids, and using the salinity method to alkaline ferment the remaining sludge can more effectively reduce sludge. This method not only solves the problem of insufficient carbon source in the activated sludge process of the sewage treatment plant, but also solves the problem of treating a large amount of excess sludge in the sewage treatment plant.

Contents of the invention

Aiming at the problem of limited acid production and short stabilization time of residual sludge fermentation under alkaline conditions, the invention proposes a method for enhancing acid production of residual sludge by adding NaCl to alkaline fermentation. This method uses a small SBR device to change the traditional simple addition of alkali to increase the fermentation rate of sludge, and at the same time add sodium chloride as an auxiliary agent to solve the problem of sludge fermentation stabilization time.

A kind of adding NaCl that the present invention proposes strengthens residual sludge alkaline fermentation acid production method, and its characteristics are as follows:

1) Take the SBR pilot sludge as the initial start-up sludge of the fermentation unit, the sludge concentration MLSS=8000-9000mg/L, pH=7-8, SCOD=30-40mg/L; the sludge index after cleaning is SCOD= 0-5mg/L, NH ₄ -N=0mg/L, NO ₃ -N=0mg/L, sludge concentration MLSS=8000-9000mg/L, then put the sludge into fermentation reactor 1 and start the agitator at the same time 2 to stir;

2) When the remaining sludge in the reactor reaches the marked scale, start the NaCl chemical pump 4.1, pump the NaCl solution, and control the NaCl concentration in the reactor to 0.2-0.5mol/L, and the NaCl feeding method is one-time dosing;

3) Configure 1-2mol/L NaOH solution in the alkali chemical tank 3, and after the NaCl solution is pumped into the reactor and stirred for 30-50min, start the pump 3.1 to pump NaOH into the fermentation reactor;

4) Keep the temperature of the fermentation reactor at 20-30°C, the pH of the mixed solution=8-10, MLSS=8000-9000mg/L, ORP=-100～-150mv;

5) Fermentation reactor 1 detects TVFA, SCOD, NH ₄ -N, PO ₄ ^3- indicators during operation; after fermentation reactor 1 operates for 5-6 days, TVFA=1700-2200mgSCOD/L, SCOD=3500-4000mg/L L, NH ₄ -N=200-250mg/L, PO ₄ ^3- =50-60mg/L, and it can be stable for more than 6 days depending on the fermentation success.

First add NaCl and stir for 30-50 minutes before adding NaOH. On the one hand, the osmotic pressure of the microbial cells in the reactor will increase, some microorganisms will lyse, and a large amount of cell components will be released, while the other part of the microbial activity will be inhibited. The dehydrogenase activity decreases, the new metabolism slows down, and the microorganisms will not die quickly after adding NaOH, and the surviving microorganisms provide strains for subsequent domestication; stage;

Description of drawings

Fig. 1 is a schematic diagram of the application device of the present invention.

Detailed ways

The schematic diagram of the application device of the present invention is shown in Figure 1, wherein fermentation reactor 1, stirring paddle 2, NaOH chemical tank 3, NaOH chemical pump 3, NaCl chemical tank 4, salt chemical pump 4.1, pH measuring instrument 5, ORP measuring instrument 6 , sampling port 7.

Take the pilot sludge, its properties are as follows: sludge concentration MLSS=8000-9000mg/L, pH=7-8, SCOD=30-40mg/L. The properties of the sludge after cleaning are as follows: SCOD=0-5mg/L, NH ₄ -N=0mg/L, NO ₃ -N=0mg/L, sludge concentration MLSS=8000-9000mg/L, put the sludge into the fermentation reaction In the device-1, start the agitator at the same time to stir, so that the activated sludge and the agent are fully mixed. Configure 2mol/L NaOH solution, first put NaCl into the device, control the NaCl concentration in the device to 0.5mol/L, pump NaOH into the device after 30 minutes, and control the pH at 9-10.

After 5-6 days of sludge fermentation, TVFA=1700-2200mgSCOD/L, SCOD=3500-4000mg/L, NH ₄ -N=200-250mg/L, PO ₄ ^3- =50-60mg/L, and can be stable6 The fermentation success is regarded as more than one day. Simply add NaOH solution, after 7-8 days of fermentation, TVFA=1000-1500mgSCOD/L, SCOD=3000-3500mg/L, NH ₄ -N=200-250mg/L, PO ₄ ^3- =50-60mg/L. It can be seen that adding NaCl can increase the acid production of sludge alkaline fermentation.

Claims (1)

1. add NaCl strengthening excess sludge alkaline fermentation and produce a sour metering method, its feature is as follows:

1) getting SBR pilot scale mud is fermentation unit primary starting mud, its sludge concentration MLSS=8000-9000mg/L, pH=7-8, SCOD=30-40mg/L; After cleaning, mud index is SCOD=0-5mg/L, NH ₄-N=0mg/L, NO ₃-N=0mg/L, sludge concentration MLSS=8000-9000mg/L, then drop into mud in fermentation reactor (1), starts agitator (2) simultaneously and stir;

2) NaCl compound pump (4.1) is started when excess sludge reaches mark scale in fermentation reactor (1), NaCl solution is pumped into, controlling NaCl concentration in fermentation reactor is that 0.2-0.5mol/L, NaCl enter prescription formula for once to add;

3) configure the NaOH solution of 1-2mol/L in alkali chemical tank (3), after NaCl solution pumps into fermentation reactor and stirs 30-50min, NaOH squeezes in fermentation reactor by ejector priming (3.1);

4) keep fermentation reactor (1) temperature at 20-30 DEG C, pH of mixed=8-10, MLSS=8000-9000mg/L, ORP=-100 ~-150mv;

5) fermentation reactor (1) is in operation and detects TVFA, SCOD, NH ₄-N, PO ₄ ^3-index; Fermentation reactor (1) operation 5-6 days after, TVFA=1700-2200mgSCOD/L, SCOD=3500-4000mg/L, NH ₄-N=200-250mg/L, PO ₄ ^3-=50-60mg/L, and Absorbable organic halogens is looked and is fermented successfully for more than 6 days.