First, let's understand the four phenomena of anaerobic reactor acidification:

PHThe pH in the reactor dropped significantly

VFA increased significantly

COD removal efficiency is greatly reduced

Biogas production continues to decrease

Usually, these phenomena occur simultaneously. Once the above phenomenon occurs, please pay sufficient attention.

Cause Analysis

Acidification of anaerobic reactor! How to deal with it? The source of acidification in anaerobic reactor is that the methanogenic ability of methanogenic bacteria in anaerobic sludge is not enough to decompose the organic acid produced by hydrolytic acidifying bacteria. The undegraded VFA concentration rises, further inhibiting methanogens, causing the reactor to continue to acidify, forming a vicious cycle, and causing the reactor to acidify.

The main causes of acidification are as follows:

Nutrient deficiency

Unsuitable pH or temperature conditions

Due to overload operation

Wastewater is mixed with toxic substances

Treatment

Once the acidification of the anaerobic reactor occurs, for whatever reason, this trend needs to be quickly reversed, and the following two emergency measures should be taken.

1. Significantly reduce operating load

Reduce the load as much as possible, it can be reduced to 50%, and even the treatment of wastewater is suspended.

At the same time, if the anaerobic reactor is provided with an external circulation pipeline, it is circulated through a circulation pump until the VFA returns to normal.

2. Take various measures to prevent the effluent pH from falling below the normal range (6.5)

If the pH value of the anaerobic reactor outlet water drops below 6.5 or even lower, the pH value of the inlet water of the reactor must be appropriately increased to maintain a suitable pH environment in the reactor. (The magnitude of the increase in the pH of the inlet water depends on how much the pH in the reactor has decreased. In some cases, the pH of the inlet water can be adjusted to above 8.0 or even 9.0.)

When the pH value in the reactor drops below 5.0, the reactor acidification is very serious. At this time, the wastewater in the anaerobic reactor can be replaced with clean water, the VFA concentration in the reactor can be quickly reduced, and the normal pH environment in the reactor can be restored as soon as possible.

Through the above two measures, if the reason for the acidification of the reactor is only overload, as long as it is not serious enough to cause a large amount of anaerobic sludge loss, the VFA in the reactor will drop below 200mg / l within 24 hours to several days. The value will return to normal levels. Even if the degree of acidification is too severe or the reactor cannot be fully restored due to other reasons, the degree of acidification can be relieved, and time can be gained for subsequent identification of the cause and taking further countermeasures.

After the acidification of the reactor is restrained, low-load operation can be performed, and then the load is gradually increased according to the operating conditions until the operating load and efficiency of the reactor returns to the normal level before acidification