Reuse of alcohol wastewater from dry potato in distillery

Technological process

Firstly, the alcohol waste liquid enters into the regulating tank to homogenize the water quality and quantity, and then it is added into the new water purification agent zbjh-1 developed by ourselves, and then it is lifted to the centrifugal separator by the submerged pump. The separated distiller's grains are sold as feedstuff. The filtrate flows into the settling tank, where lime is added for neutralization and a bactericide is added for sedimentation separation. The supernatant is pumped back to the production workshop for mixing, and the precipitate enters the inclined plate settling tank for further sedimentation and then pumped into the UASB anaerobic tank together with the returned sludge for anaerobic fermentation. The biogas produced by UASB anaerobic tank enters the boiler for combustion supporting through water seal, and the effluent enters the vertical flow sedimentation tank for sedimentation. After sedimentation, the sludge flows back, the supernatant enters the pre aeration tank, diluted with waste cooling water and flows into the biological contact oxidation tank for aerobic biological treatment, so that some organic pollutants can be decomposed and removed here, and then enter the perforated swirl inclined plate sedimentation tank for flocculation and sedimentation treatment. The water from the inclined plate sedimentation tank flows into the fly ash slag filter for filtration and adsorption, and then it can be discharged up to the standard.

Reuse

① selection of separation equipment

The alcohol waste liquid has high temperature (> 95 ℃), high acidity and more sand, which will cause certain corrosion and wear to the equipment. The key of recycling technology is how to improve the separation efficiency and separate the solid in the waste liquid as much as possible to meet the requirements of the solid content in the recycled water. After comparing the equipment performance and treatment effect, dfil-600 solid-liquid separator and 400 mesh screen were selected.

Main technical parameters of dfil-600 solid-liquid separator:

The treatment capacity is 8-10m3 / h; the rotating speed is 1700r / min; the temperature of the separated liquid is ≤ 100 ℃; the particle size of the solid in the treated wastewater is ≤ 400 mesh; the moisture content of the separated distiller's grains is 85% - 87%.

② development of special treatment agent

As the viscosity of distiller's grains is large after cooking, it is necessary to add a treatment agent to facilitate solid-liquid separation. Combined with the properties of distiller's grains waste liquid, a new treatment agent zbjh-1 was developed, which was suitable for distiller's grains waste liquid separation. It improved the solid-liquid separation effect of centrifuge and reached the technical index of waste liquid recycling.

③ adjustment of process parameters

The cooking temperature is 120-130 ℃; saccharification and H2SO4 are added to adjust the pH value to 4-4.5. When the fermentation tank is full of 1 / 3, add 1 μ g / ml of penicillin in the mash, and add alkali to the reuse solution for neutralization until the pH value is 1.0-2.0.

For finished mash:

① the pH value is basically maintained at 4.5-6.5.

② the residual reducing sugar was (0.11-0.49) × 10-2 g / ml, which fluctuated greatly.

③ the concentration of total sugar fluctuated (0.42% - 0.56%) due to the sugar content in reused water, but it was not accumulated basically.

Alcohol products:

① methanol and volatile acid were stable below 0.06 × 10-2 and 0.3 × 10-2 g / ml respectively, and recycling had no effect on them.

② only 4 times of oxidation time less than 15 min occurred in 16 batches of recycling, indicating that the impurities produced in the fermentation process are less through saccharification and acid regulation.

Distiller's grains waste liquid:

The viscosity, density, TS, SS, COD, total acid and volatile acid of distiller's grains waste liquid and filtrate fluctuate basically in the stable range.

1.5 advanced treatment

Most of the waste liquid can be reused for production after physicochemical treatment, but about 10% - 15% of the waste liquid still needs to be treated in depth. Therefore, anaerobic aerobic treatment process is adopted to make this part of waste water finally meet the discharge standard. Its main facilities and equipment process parameters are:

① UASB anaerobic reaction tank: made of steel, with three-phase separator inside. The designed cod volume load is 3.5 kgcod / (M3 · d), the effective volume is 500 m3, the hydraulic retention time is 10 days, and the COD removal rate is 85%.

② pre aeration tank: reinforced concrete structure, with perforated aeration pipe in the tank, with an effective volume of 50m3, where it is diluted by 4 times of waste cooling water.

③ contact oxidation tank: reinforced concrete structure, divided into two grids, with microporous aerator and semi soft composite filler, designed cod volume load is 1.5 kgcod / (M3 · d), effective volume is 200m3.

④ inclined plate sedimentation tank: made of steel, equipped with inclined plate filler with an aperture of 50 mm, with a surface load of 1 m3 / (M2 · h).

⑤ dosing device: the agent used is polyaluminium chloride, with 1 dosing box and 1 dosing pump respectively.

⑥ pump room: the plane size is 12 m × 6 m, which is also used as the blower room. There are two roots fans in it, one for use and one for standby.

⑦ sludge dewatering machine room: the plane size is 12 m × 6 m, which is equipped with box type plate and frame filter press (1 set), polyacrylamide dosing box (1 set) and dosing pump (1 set).