Analysis Of Efficient Biological Treatment Technology

The effluent of two stage effluent from printing and dyeing wastewater is not biodegradable and has certain difficulty in biodegradation. The emphasis of biological method is to develop a new bioreactor with enhanced biotechnology to further remove COD and chromaticity.

(1) biological aerated filter (BAF).

After printing and dyeing wastewater treated by two levels of biochemical treatment, the COD and BOD in the water were relatively low. The biofilter on the aerated biofilter packings had larger specific surface area and higher affinity for organic matters in the wastewater.

Zhou Feng [13] studied the treatment of two effluent from dyeing wastewater by BAF, and increased BAF depth after hydrolysis acidification + aerobic process.

When the influent is COD<200 mg/L, the hydraulic load is 1 ~ 2 m3/ (M2 h), and the gas water ratio is (2~3): 1, the COD COD removal rate of effluent is above 50%, reaching the first level discharge.

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The biological aerated filter has high biological concentration and high organic loading, stable treatment effect and good effluent quality.

The smaller the particle size of the filter media is, the better the effect will be. However, the smaller diameter will shorten the working period, and the filter material is not easy to clean, and the corresponding backwash water will also increase.

Therefore, the key to the function of biological aerated filter is to select the appropriate size of filter media.

(2) moving bed biofilm reactor (MBBR).

MBBR is a new type of biofilm reactor.

Microorganisms are enriched in fillers in the reactor.

Suspended in the reactor and flowing with the mixed liquid, the three gas, water and fillers can be fully contacted in the reactor. The oxygen utilization rate and the mass pfer efficiency of the organic pollutants are high, and the activity of the biofilm is higher. The aged biofilm is easy to fall off the surface of the packing.

MBBR also has the advantages of no backwash, strong impact resistance and stable effluent quality [14].

At present, there is not much research on the treatment of printing and dyeing wastewater by MBBR process.

Huo Tao Mei [15] found that MBBR had a good removal effect on COD and ammonia nitrogen two indicators when advanced treatment of printing and dyeing wastewater.

The influent COD decreased from 200 mg/L to below 50 mg/L, and ammonia nitrogen decreased from 10 mg/L to 2 mg/L, but the color removal rate was only 25%.

There are many kinds of organic pollutants in printing and dyeing wastewater, and the multi strain system on biological filler has greater degradation ability. Therefore, MBBR as a deep treatment process has great advantages for two grade biochemical treatment effluent with low organic concentration.

In the future, the research and application of MBBR in advanced treatment of printing and dyeing wastewater can be regarded as a development direction.

(3) membrane bioreactor (MBR).

Membrane bioreactor, which combines membrane separation and biodegradation, can remove most of the residual COD, chroma and all SS in the wastewater.

Then, the NF (RO) process is further processed to remove most of the salinity, and the effluent quality can generally meet the requirement of reclaimed water.

Dai Shu, et al. [16] for reuse purposes, the external MBR and COD filter combined with nanofiltration membrane were used to treat printing and dyeing wastewater. The results showed that the removal rate of COD, chroma and turbidity of the system reached 99%, and the conductivity removal rate was 97%.

P.Schoeberl et al. [17] first used MBR and NF to treat printing and dyeing wastewater. The effluent water quality all met the target of reusing water. However, considering the technical difficulty and high economic cost, UF instead of NF also achieved good results.

The advantages of MBR are that the process is short, the floor area is small and the water quality is stable. The disadvantages are similar to the membrane separation technology, mainly due to the short life, high cost and high power consumption caused by membrane fouling.