Wastewater treatment process and worm reactor (1)

Choosing worms suitable for sludge reduction does not mean to obtain a high sludge reduction rate.
It is very important to maintain the stable presence and growth of worms in the wastewater treatment system
.
Therefore, it is very important to choose an appropriate treatment process and provide a suitable habitat for the growth of oligochaete worms

(1) At the beginning of the wastewater treatment process, people directly added worms to the activated sludge system in an attempt to enhance their growth to achieve sludge reduction, but found that they could not be controlled in practice.
For example, attached worms like earthworms are easy to sink.
At the bottom of the tank, it cannot be evenly distributed in the aeration tank, and it may also be lost with the discharged sludge, which will affect the stability of the worm reduction sludge
.
Therefore, a separate worm reactor is used to inoculate worms, and the wastewater treatment system is nothing more than an activated sludge process, especially the traditional activated sludge process (CAS), and the remaining activated sludge is discharged into the worm reactor for reduction.

(2) New type of worm reactor.
Domestic scholars have developed a composite biological sludge reduction reactor in which free and attached worms grow in different areas of the reactor to treat the remaining sludge and return sludge discharged from the sewage biological treatment system.
, Where the attachment worm growth area is not only added with filamentary plastic carrier fillers for the attachment of earthworms, but also through sludge circulation to avoid the loss of free worms and ensure the stability of their growth environment, as shown in Figure 9-3
.
Studies have shown that inoculating earthworms to reduce the quality of sludge, the reduction rate reaches about 48%

Figure 9-3 Schematic diagram of the composite biological sludge reduction reactor process

In order to expand the contact area between earthworms and sludge and make full use of the reactor volume, some domestic researchers have placed 33 small containers (length 0.
28m, length 0.
28m, (0.
03m wide and 0.
03m high) Place trembling earthworms, establish an integrated wastewater treatment system and run it continuously for 235 days
.
When the sludge is returned to the activated sludge treatment system or discharged in two operation modes, the remaining sludge reduction ratio and the average sludge yield are 46.

Figure 9-4 Vertical circulation integrated hydrogenation ditch (IODVC)-schematic diagram of worm reactor system

Dutch scholar T, LGHendrickx proposed an important design parameter—the digestibility of worms to sludge per unit area of ​​the worm reactor [gTSS/(m ² ·d)].
Under the condition of ensuring a stable density of L.

In order to strengthen the fixation of the worms on the carrier, the new worm reactor designed by the Dutch researcher Hellen JHElissen uses meshes with a diameter smaller than the diameter of the worm and a sponge-like carrier (a diameter of 300um), as shown in Figure 9-5
.
The upper part of the reactor is an inverted beaker.