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Treatment Of High Concentration Cotton Dyeing Wastewater By H / O Process

2011/4/7 12:53:00 63

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printing and dyeing

Wastewater treatment started earlier in our country.

In the early 1970s, the relevant units carried out research work on printing and dyeing wastewater treatment.

After the mid 80s, governance technology entered a new period of development and research, and achieved many new scientific research achievements, such as biological contact oxidation biochemical treatment process, anaerobic (hydrolysis) aerobic treatment process and so on.

And cotton

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And printing and dyeing wastewater, because of its high concentration desizing wastewater, makes it different from other textile printing and dyeing wastewater.

The author introduces 1800 T / D cotton spinning and dyeing wastewater treatment project of a printing and dyeing plant in Pujiang County of Zhejiang province.

1 Engineering Design

1.1 project overview

A printing and dyeing factory in Pujiang County of Zhejiang province mainly deals in the desizing and dyeing and finishing business of cotton cloth.

The plant produces a daily amount of 1800 T / D.

The production process and source of sewage are as follows: embryo cloth - boiling, desizing - bleaching - washing - coloring - fixing - finishing - finished cloth.

Source of sewage: (1) cooking and desizing sewage.

Its water quality is pH11 ~ 13, CODcr5 000 ~ 12000 mg / L; sewage mainly contains PVA, starch and other NaOH and other auxiliaries.

(2) bleach water washing sewage.

Its water quality is pH8-10, CODcr100 ~ 300ms / L, and sewage contains mainly Bleaching Auxiliaries such as H202.

(3) dyeing wastewater.

Its water quality is pH7.8 ~ 9, CODcr600-1 000mg / L, chroma is 800~1600 times, sewage mainly contains dyes, accelerant and so on.

(4) finishing sewage.

Its water quality is pH6 ~ 9, CODcr200 ~ 400mg / L, sewage mainly contains softeners, detergents and other auxiliaries.

Mixed wastewater quality: CODcr 2000 mg / L, SS 500 mg / L, chroma 800 times, pH 9~13.

After treatment, the quality of the wastewater reaches the first level discharge standard of GB 4287-1992 of the textile dyeing and finishing industry pollutant discharge standard.

Specific indicators: CODcr100mg / L, SS70mg / L, chroma 40 times, pH6-9.

One point two

Technology

Technological process

The sewage treatment process is shown in Figure 1.

After the sewage is separated from the larger waste by the grille, the sewage flows from the middle to the regulating pool.

The outlet of the regulating tank is lifted by the lifting pump and enters the hydrolysis acidification tank from the bottom.

In hydrolytic acidification pond, hydrolytic acidification is difficult to degrade macromolecule dye and PVA and so on, so as to improve the biodegradability of wastewater.

After that, the wastewater enters the biological contact oxidation pond. Further biochemical treatment is carried out, and the biological contact oxidation tank is aerated by a blower variable microporous aerator.

The H / O pool removes most CODcr and BOD5, so that the effluent basically meets discharge requirements.

The sewage finally entered the sedimentation tank. After adding the chemical treatment, the effluent reached the discharge standard and discharged into the nearby river course.

In the management of sewage treatment works.

In order to ensure microbial nutrition, it is required to add appropriate amount of phosphate fertilizer to m (BOD5):m (P) =200:1 during operation, or to provide domestic sewage.

The sewage sludge thickener of the sedimentation tank was initially concentrated and then pumped to the plate and frame filter press after filtration.

Dry mud is incinerated or burying, and the filter water is returned to the regulating pool.

1.3 main structures and units

1.3.1 neutralization tank

Function Description: workshop wastewater is neutralized and water quality and quantity are adjusted.

Gage parameters: HRT HRT 12 h; size: 25 m x 10.0113 x 4 m: equipment configuration: 1 sets of coarse and thin grille, 1 sets of sulphuric acid dosing system, 2 sets of industrial digital display acidity meter, 1 sets of perforation aeration system, 3.QW80-40-7 of.QW80-40-7 submersible sewage pump (2 for 1), and construction: underground steel concrete structure.

1, 3.2 hydrolytic acidification tank

Function Description: wastewater is treated by hydrolysis and acidification to improve its biodegradability.

Design parameters: HRT HRT 6 h, CODcr volumetric load of 4.2 kg / (m 3 D); size: 8.5 m * 10 m * 5.5 m; equipment configuration: D150 mm x 60 m (wire length 35 35) combination packings 300, plug flow subsurface aerator 2; perforated water system 1 sets; structure: semi underground steel concrete structure.

1.3, 3 biological contact oxidation pond

Function Description: wastewater is treated in this biochemical process to remove organic pollutants: design parameters: HRT HRT 18 h, CODcr volumetric load of 1.20kg / (M3 d); size: 60.0m * 5.0mx50m, divided into 10 grids of baffled flow; equipment configuration: D150 / ll / ll * x group filler, variable microporous aerator 750 sets, Three Leaves Roots blower 2 (IV) (1 for 1); structure: semi underground steel concrete structure.

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1 and 3.4 two sedimentation tanks

Two sedimentation tank function: to achieve solid-liquid separation of effluent from aerobic pond; design parameters: inclined plate sedimentation tank, surface load 1.50m3 / (M2.H); size: 5 m x 5 m x 5 m, a total of 2; equipment configuration: D 80 mm oblique plate 2 * 50 m3.

WQ15-7-1 sludge lifting pump 2 sets (1 for 1 uses): Construction: semi underground steel concrete structure.

1.3.5 sludge thickening tank

Function of sludge thickening pond: storage and thickening sludge; design parameters: effective volume 280M3: size: 6.0m * 5.0m * 5.0m; equipment configuration: sludge mixer; structure: semi underground steel concrete structure:

1.3.6 integrated housing

Comprehensive housing function: including sludge dewatering machine room, blower room, distribution control room laboratory, duty room: size: 30.0mx3.5mx3.5m: equipment configuration: 60m2 sludge dehydrator 2 sets, Three Leaves Roots blower 2, distribution system, laboratory equipment, etc.: Structure: ground type brick concrete structure.

2 commissioning and operation

The project started construction in 2002, l0.2003, and completed the installation of civil engineering and equipment in May.

In the commissioning phase of the culture, 8 T of digested sludge and feces containing 75% of the printing and dyeing plant were cultured.

The influent flow increased gradually from small to large, and black biofilm was formed on the packing of hydrolysis tank. A yellow brown biofilm was formed on the packing of aerobic tank, and the whole system entered normal operation state.

During the commissioning process, two sludge from the sedimentation tank was refluxing to the hydrolysis tank.

The project completed its culture and commissioning in December 2003.

The monitoring results of the local environmental protection department (average daily data) are shown in Table 1.

The project has been running up to date and has been repeatedly sampled and measured.

There were basically no microorganism in biofilm on hydrolytic acidification stage fillers. The growth rate and membrane regeneration of bacteria were slower, and the shedding flocs were not easy to precipitate.

In aerobic biofilm, bacteria grow faster, filamentous bacteria are more, and the activity of membrane is better than that of hydrolytic acidification.

3 main technical and economic indicators

The main technical and economic indicators of the project are shown in Table 2.

4 Summary

(1) the H / O biochemical process is the main technology. Compared with the flocculation and sedimentation as pretreatment process, the technology has less dosage, lower sludge output and lower running cost.

(2) the hydrolytic acidification tank uses uniform water distribution at the bottom, and the mixing machine is used to prevent sludge from settling.

(3) engineering practice proves that the technology can be used to mix the desizing wastewater and other waste water with high concentration and avoid the trouble of separating the waste water.

(4) perforation and aeration in the regulating tank can remove toxic substances from subsequent biochemical treatment and solve the problem of preventing suspended sediment from being smelly.

(5) when the red reactive dye is used extensively in the workshop, the total outlet wastewater presents a certain degree of red. It is suggested that further treatment units should be added in the future design, such as ozone oxidation and decolorization.

The wastewater can be recovered by proper depth treatment, which is of great significance in the current situation of industrial water shortage in developed areas.