CN111635098A - Concrete batching plant wastewater zero discharge process - Google Patents

Abstract

The invention provides a zero-discharge treatment process for waste water in a concrete mixing station, which belongs to the field of physical treatment of industrial waste water. It mainly solves the problems of discharge of wastewater containing concrete particles in the station area, flying dust in the station, large mud coating on the ground, and decentralized treatment of wastewater from pump washing vehicles. It collects the dispersed mud, mortar and rain sewage in the station with a vacuum collection system. After being concentrated, it is lifted by a slurry pump. First, the disc screen is used to separate the coarse sand and gravel, and the aggregate is recovered, and then centrifugal separation is performed to separate the medium and fine sand and mud. Finally, After rigid membrane filtration, clean water can be obtained immediately, which can be recycled and used; the concentrated mud after centrifugal separation is press-filtered nearby, and the mud cake is output. The invention solves the problem of rapid transportation and collection of high-concentration and large-particle suspended matter, avoids the deposition, crusting and blockage of trenches and pipelines, eliminates the phenomenon of mud exposure, directly outputs solid mud cake, and can greatly improve the resource circulation of the mixing station Utilization and ecological civilization level. The invention is used for waste water treatment of concrete mixing station.

Description

Concrete batching plant wastewater zero discharge process

technical field

The invention relates to the field of waste water and dust treatment in the concrete industry and material intermediate treatment sites, in particular to a process for zero discharge of waste water.

Background technique

Raw material processing plants represented by concrete batching plants, on the one hand, accompanied by a large number of logistics and material flow in and out, there are vehicle unloading, stockpiling, material processing, special vehicles such as pump truck residual material cleaning, vehicle entry and exit, site muddy, dust flying , the problem of rain and sewage excreting a large amount of suspended solids. The discharge of high-concentration suspended solids wastewater leads to serious siltation in ditches and waterways, which is the central environmental protection problem of material processing plants represented by concrete batching plants. Secondly, the landscape in the concrete mixing plant is poor, the mud coating area is large, and the spanning period is long. The aggregate contained in the wastewater needs to be recycled, which is also the inherent development demand of the mixing plant.

Usually, a vibrating screen or a drum screen is installed in the concrete mixing station to treat the waste water of the concrete pump truck, and part of the aggregate is recovered. Before the mud is transported to the plate and frame for pressure filtration, the coarse particles in the sedimentation tank will naturally settle and harden, and it is often necessary to excavate with a forklift to allow the mud to drain and dry.

The site of the batching plant is generally flat, and the slope of the drainage ditch is not enough to avoid a large amount of sedimentation. Due to the characteristics of concrete, siltation of conveying ditches and blockage of pipelines occur frequently.

With the deepening of environmental protection and ecological concepts, the discharge of high-concentration suspended solids wastewater from concrete batching plants to outside the plant has gradually been included in the scope of sewage treatment supervision, and recycling has increasingly become a major trend.

From the perspective of recycling, the homogenization and stabilization of wastewater is the key to technology. At present, the concentration and total amount of mud derived from wastewater fluctuate greatly, which affects the reduction of concrete strength and makes the fluidity out of control.

SUMMARY OF THE INVENTION

The purpose of the present invention is to systematically solve the problem of zero discharge of high-concentration suspended solids waste water in concrete batching plants, to solve the problems of poor site landscape, poor working environment quality, and waste water recycling.

In order to achieve the above purpose, the present invention provides a zero-discharge treatment process for waste water from a concrete mixing station, which is used for the treatment of waste water in a concrete mixing station. , and/or tire washing wastewater, and/or concrete inspection wastewater treatment, and/or domestic sewage treatment six parts. Except for domestic sewage treatment, the wastewater treatment of other branches adopts the overall process of scattered collection of wastewater and then centralized treatment.

The method for dispersing and collecting wastewater is vacuum collection and/or slurry pump delivery. The centralized treatment sequentially includes a disc sieve coarse separation, a vertical centrifuge fine separation, and/or a rigid membrane filtration separation, and a filter press filter cake process.

The vacuum collection method is:

The first step is to arrange multiple vacuum collection wells in the plant area. The sewage is used to collect rainwater sewage, site cleaning wastewater, or concrete inspection wastewater. Insert a collection pipe into the well, connect an automatic valve, and use local control. The box controls the valve opening and closing according to the slag slurry level.

In the second step, the vacuum tank with a certain volume is sucked by a vacuum pump to form a negative pressure, and the mud is sucked into the vacuum separation tank from time to time through the pipeline connected to the vacuum collection well. The slurry discharge port of the vacuum tank is located at the lower bottom, and the vacuum pumping port is located at the upper top, so that the slurry and the gas in the vacuum tank are separated.

The centralized processing method is:

First, the slurry separated from the vacuum tank passes through the automatic valve, or the slurry transported by the dispersion slurry pump, enters the buffer hopper, and connects with the first slurry pump. The slurry is lifted to a certain height by the first slurry pump.

Secondly, the slurry falls into the disc screen with staggered rotating discs side by side. The oversize particles are sand and gravel particles larger than the first separation particle size, and the underscreen is relatively fluid slurry smaller than the first separation particle size.

In the third step, the slurry is introduced into the vertical rotor centrifugal solid-liquid separator, and the fine particles larger than the second separation particle diameter are separated by centrifugal action and then sink and concentrate around the circumference. The low-concentration slurry of suspended solids smaller than the second separation particle size is discharged from the center.

In the fourth step, the centrifugally separated mud smaller than the second separation particle size is connected to the booster pump. When the second separation particle size meets the concrete production requirements, the booster pump will transport the slurry to the production line or access the branch wastewater treatment process.

In the fifth step, the booster pump feeds the slurry smaller than the second separation particle size into the sintered metal microporous filter. The filtered clean water enters the clean water pool and is further integrated into the concrete production system or partially connected to the tire cleaning system for recycling.

In branch step 1, the concentrated mud larger than the second separation particle size obtained from the centrifuge is directly transferred to the filter press through the valve. Relying on the natural water level difference or air pressure in the filter press, water seeps out through the diaphragm to dehydrate the mud in the tank, or after repeated slurry storage, enough suspended particles are accumulated to form a solid mud cake. Finally unload the solid mud cake.

In branch step 2, the filtered fine particle concentrated mud is separated from the filter, and directly transferred to the filter press through the valve. Relying on the natural water level difference or air pressure in the filter press, water seeps out through the diaphragm, dehydrating the mud in the tank, or after repeated slurry accumulation, enough suspended particles are accumulated to form a solid mud cake. Finally unload the solid mud cake.

The waste water vacuum collection method can be completely replaced by the slurry pump self-dispersed collection well pumping method. Considering the factor of equipment wear, the vacuum collection method is preferred.

In step 1, the concrete pump truck directly dumps the cleaning wastewater formed by cleaning the tank body into the first disc screen or the second disc screen arranged adjacently. The selected sand and gravel particles larger than the first separation particle size fall directly to the ground or enter the screw conveyor to be transported to a predetermined position. The sieves smaller than the first separation particle size flow and merge into the centrifuge.

In step 2, the concrete vehicles entering and leaving the factory are cleaned by the tire cleaning machine, and the tire cleaning wastewater is transported to the fourth step by the second slurry pump to the first disc screen, or transported to the third. Step to the buffer hopper.

In step 3 of subdivision, the domestic sewage enters the integrated treatment system, and after intensified stirring anaerobic, aerobic aeration, and constant-pass membrane filtration, the obtained reclaimed water is merged into the subdivision wastewater treatment process or the clear water tank.

Description of drawings

Fig. 1 is a schematic diagram of a process flow diagram of zero-discharge treatment of waste water in a concrete mixing station according to the present invention.

Fig. 2 is a simplified schematic diagram of the process flow of zero-discharge treatment of waste water in a concrete batching plant according to the present invention.

Description of reference numerals

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary, and are intended to explain the present invention, but should not be construed as a limitation of the present invention.

Example 1:

The following describes a zero-discharge treatment process for wastewater from a concrete batching plant according to an embodiment of the present invention with reference to the accompanying drawings. Figure 1.

The vacuum collection system is adopted, and the scattered and discontinuous site cleaning sewage, rainwater, and production wastewater are pumped into the vacuum separation tank through the collection wells arranged at multiple points, and then the sludge is lifted to the first plate through the slurry pump. Plate sieve, the grit larger than the first separation particle size is transported by the disc, drained to one side, and falls into the screw conveyor, and the under-sieve mud smaller than the first separation particle size falls into the vertical rotor centrifuge slurry. The particles larger than the second separation particle size settle and concentrate at the periphery of the centrifugal field, and the particles smaller than the second separation particle size overflow from the center of the centrifugal field, pass through the booster pump, and enter the rigid membrane filter at a certain pressure to output clean water. The sludge settled and concentrated from the centrifuge falls into the filter press through the valve, and the valve is closed to filter the mud. The sludge separated from the centrifuge sedimentation also falls into the filter press through the valve to filter and output the mud cake.

The waste water from the concrete pump truck is directly dumped on the second disc screen, the material under the screen is fed into the centrifuge, and the sand and gravel above the screen is fed into the screw conveyor.

Vehicles entering and leaving the mixing station are cleaned by tires, so that the road dust inside and outside the site can be controlled, and the cleaning mud is transported to the first disc screen by the second slurry pump.

Domestic sewage is filtered through enhanced anaerobic, aerobic, and rigid membranes, and then flows into the clean water pipeline.

The technical principle of the present invention has the following points:

1) Advantages of vacuum collection

Vacuum collection is a kind of rapid conveying of solid-liquid-gas three-phase mixed system, which operates intermittently. Each time suction is accompanied by the airflow to clean the pipeline, and the wear on the pipeline is significant, so the siltation, crusting and blockage of the pipeline and ditches are eliminated.

Vacuum collection is suitable for intermittent material flow, and it can also pump and transport stones with the same diameter as the pipe. Strong adaptability to materials.

The vacuum collection can withstand the undulations of 2-4m in the pipeline, and there are almost no special requirements for the site, and the flat pipes and up and down bends are not affected, which eliminates the need for drainage ditch grading.

2) Advantages of disc screen for separating grit

The disc screen is formed by the gaps formed by the staggered discs to form the separation particle size. The screen surface is dynamic and has a strong ability to eat pulp. The grit can be quickly separated, transferred, and drained of free water.

3) Short process is feasible

Concrete mixing station wastewater is high-concentration suspended solids wastewater, and the vertical rotor centrifuge uses the rotor to create a centrifugal separation field. The output low-concentration slurry smaller than the second separation particle size has uniformity, and can be directly entered into the concrete mixing system or into the tire washing cycle. If the circulation of clean water is required, it is further conveyed to the filter by the booster pump to separate the clean water.

4) Rigid filtering

The pore size of the sintered metal microporous filter element has been as small as 0.5 microns, and it can be used to filter the clear liquid settled by centrifugation to obtain clear water with a turbidity of less than 1. The filter pores are stable and inelastic, and the filtered mud film is deposited on the surface of the filter element, which is easy to fall off into pieces when backwashed, and the pores are easy to regenerate.

Embodiment 2:

The following describes a simplified zero-discharge treatment process for wastewater from a concrete mixing plant according to an embodiment of the present invention with reference to the accompanying drawings. Figure 2.

The difference from the first embodiment is that there is no tire washing wastewater treatment and domestic sewage treatment, and no clean water recycling is required, only qualified mud circulation is considered.

beneficial effect

Compared with the prior art, the present invention has the following beneficial effects:

1) The whole process is carried out in a closed manner, without the exposed sedimentation tank, there will no longer be opportunities for forklifts to salvage silt and mud, and the appearance of the station has been significantly upgraded;

2) All waste water in the station area is no longer discharged, and zero discharge is practically achieved;

3) The sand and gravel materials are fully recycled;

4) Produce solidified mud cake, which is convenient for storage and transportation;

5) The arrangement of the collection system is concealed;

6) The facilities are centralized and integrated, and the floor area is small;

7) The tail liquid is stable and uniform, which is convenient for the recycling of the mixing station;

8) Tire cleaning realizes clean water or low turbidity water cleaning, improves car washing efficiency, and greatly reduces nozzle wear.

Claims (7)

1. A zero discharge treatment process of waste water of a concrete mixing plant is used for treating the waste water of the plant area of the concrete mixing plant and is characterized by comprising six parts, namely rainwater waste water treatment, site cleaning waste water treatment, concrete pump truck washing waste water treatment, and/or tire cleaning waste water, and/or concrete inspection waste water treatment, and/or domestic waste water treatment; except for domestic sewage treatment, all other parts of wastewater treatment adopt an overall process of collecting wastewater dispersedly and then carrying out centralized treatment;

the dispersed wastewater collection mode is vacuum collection and/or slurry pump conveying; the centralized treatment sequentially comprises the processes of disk screen coarse separation, vertical centrifuge fine separation, and/or rigid membrane filtration separation, and filter pressing and mud cake pressing by a filter press.

2. The zero discharge treatment process of waste water of the concrete mixing plant according to claim 1,

the vacuum collection mode is as follows:

firstly, arranging vacuum collecting wells at multiple points in a factory area in a dispersed manner, wherein sewage is used for collecting rainwater sewage, field cleaning wastewater or concrete inspection wastewater in the factory area, inserting a collecting pipe into the wells, connecting an automatic valve, and controlling the valve to be opened and closed by using an on-site control box according to the slurry level;

secondly, pumping a vacuum tank with a certain volume by using a vacuum pump to form negative pressure, and pumping the slurry into a vacuum separation tank at random through a pipeline communicated with a vacuum collection well; the vacuum tank slurry discharge port is positioned at the lower bottom, and the vacuum pumping port is positioned at the upper top, so that the slurry and the gas in the vacuum tank are separated.

3. The zero discharge treatment process of waste water of the concrete mixing plant according to claim 1,

the centralized processing mode is as follows:

firstly, the slurry separated from the vacuum tank enters a buffer hopper through an automatic valve or the slurry conveyed by a dispersed slurry pump and is butted with a first slurry pump; lifting the slurry to a certain height by a first slurry pump;

secondly, the slag slurry falls into a disc screen of parallel and staggered rotating discs, the oversize is sand and gravel particles with the particle size larger than the first separation particle size, and the undersize is slurry with stronger fluidity and smaller than the first separation particle size;

thirdly, guiding the slurry into a vertical rotor centrifugal solid-liquid separator, and carrying out circumferential sinking concentration on fine particles with the particle size larger than the second separation particle size after the fine particles are separated by centrifugal action; the suspended matter low-concentration slurry with the particle size smaller than the second separation particle size is discharged from the center;

fourthly, the centrifugally separated slurry with the particle size smaller than the second separation particle size is connected into a booster pump; when the second separation particle size meets the production requirement of concrete, the booster pump conveys the slurry to a production line or is connected to a sub-part wastewater treatment process;

branching the step 1, directly transferring the concentrated slurry with the particle size larger than the second separation particle size obtained by the separation of the centrifuge into a pressure filter through a valve; water seeps out through a diaphragm in the filter press under the action of natural water head difference or air pressure, so that slurry in the tank is dehydrated, or sufficient suspended particles are accumulated through repeated slurry receiving for many times, and a solid mud cake is formed; finally discharging the solid mud cake.

4. The zero discharge treatment process of waste water of the concrete mixing plant according to claim 2,

the booster pump inputs the slurry with the particle size smaller than the second separation particle size into the sintered metal microporous filter; the filtered clean water enters a clean water tank and is further either blended into a concrete production system or partially connected into a tire cleaning system for recycling;

separating the filtered fine particle concentrated slurry from the filter, and directly transferring the slurry to a filter press through a valve; water seeps out through a diaphragm in the filter press under the action of natural water head difference or air pressure, so that slurry in the tank is dehydrated, or sufficient suspended particles are accumulated through repeated slurry collection for many times, and a solid mud cake is formed; finally discharging the solid mud cake.

5. The zero discharge treatment process of waste water of the concrete mixing plant according to claim 2,

the concrete pump truck directly pours the cleaning wastewater formed by the cleaning tank body into the first disc screen or the second disc screen which is adjacently arranged; the selected sand and gravel particles with the particle size larger than the first separation particle size directly fall to the ground or are gathered into the spiral conveyer to be conveyed to a preset position; undersize smaller than the first separation particle size flow and join and are merged into the centrifuge.

6. The zero discharge treatment process of waste water of the concrete mixing plant according to claim 2,

and (3) cleaning the concrete vehicles entering and leaving the plant area by a tire cleaning machine, and conveying the tire cleaning wastewater to the first disc screen by using a second slurry pump or conveying the tire cleaning wastewater to the buffer hopper.

7. The concrete mixing plant wastewater zero emission treatment process according to one of the claims 3 and 4,

domestic sewage enters an integrated treatment system, and through reinforced stirring anaerobic treatment, aerobic aeration and constant-flux membrane filtration, the obtained reclaimed water is converged into the branch wastewater treatment process or the clean water tank.

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