RU2359924C1 - Method of waste water decontamination and related plant - Google Patents

Abstract

FIELD: treatment facilities. ^ SUBSTANCE: invention relates to waste water decontamination using floating plant Eichornia crassipes (Water hyacinth). The method of waste water cleaning provide for waste water supplying into distributing channel and to operating channels where water flows in laminar mode at the same speed no more than 5 m/hour at waste water temperature 23-30C and air temperature 25-35C. At the same time, water hyacinth is planted on the water surface in operating channels. The proposed method is realised in the plant made up from a distributing channel with receiving lattice being over the said channel and a composite draining channel. The channels are connected between each other by means of a line of parallel operating channels where water hyacinth is planted. The above-mentioned operating channels are perpendicular to the distributing channel and clean water channel or inclined to them and provided with cross movable partitions. ^ EFFECT: water is evapourated through water hyacinth leaves and animal food is produced. ^ 2 cl, 4 dwg

Description

The invention relates to the field of treatment of household, industrial and other wastewater using a floating plant Eichornia crassipes (Water hyacinth) - eichornia or water hyacinth, a representative of higher aquatic plants, as a load of artificial or natural hydrobotanical plots.

Traditionally used methods are not always suitable for natural, decorative and bathing water bodies due to significant costs, insufficient approach of wastewater to natural quality and thereby incomplete reduction of the harmful effects of these waters on the environment, which leads to a deterioration of the existing microbiocenosis of the reservoir and the coast.

A known method of wastewater treatment with partial neutralization, according to which, a floating plant is placed in a nutrient solution at a positive temperature of ambient air and nutrient solution. The ambient temperature is maintained at least + 16 ° C, and the temperature of the nutrient solution in the range from + 15 ° C to + 36 ° C. As a nutrient solution, use contaminated water with a pH of 5-9 and with an initial content of the main pollutants in concentrations up to, mg / l: ammonium nitrogen 200, phosphates 18, iron 22, alkalis 17, surfactants 14, sulfides 21, oil products 25, phenols 340, suspended solids 1500 with BOD-5 not more than 1000 mg O ₂ / l and COD not more than 2000 mg O ₂ / l. Plants are additionally artificially illuminated with green-red spectrum lamps with a capacity of at least 300 W / m ^{2 for} no more than 14 hours a day, mainly from 5 a.m. to 19 p.m. In the cold period, plants are covered with a translucent film that increases the red component of the spectrum. In the space under the film, ventilation is periodically carried out in the absence of drafts. The air under the film is additionally heated, for example, by fan heaters. The temperature regime of air under the film is maintained by creating a moisturizing layer in the form of artificial irrigation or an aerosol “blanket”. Contaminated water is additionally heated or cooled. EFFECT: creation of conditions for plant adaptation, maintenance of their vital functions throughout the year, and optimization of conditions for the effective treatment of contaminated waters.

Closest to the claimed invention is a method of wastewater treatment with partial neutralization, using eichornia as a floating in the nutrient solution loading of the hydrobotanical zone. Wastewater is used as a nutrient solution in the hydrobotanical zone at an initial concentration of impurities of pollutants: ammonium nitrogen not more than 100 mg / l, phosphates not more than 50 mg / l, iron not more than 25 mg / l, surfactant not more than 15 mg / l, sulfates no more than 160 mg / l, oil no more than 60 mg / l, phenols no more than 350 mg / l, with BOD no more than 1000 mg O ₂ / l and COD no more than 2200 mg O ₂ / l, with a pH in the range of 5 -9. Vegetation of eichhornia in the hydrobotanical zone is carried out at a temperature of ambient air and water of at least 19 ° C with natural and / or artificial lighting. Biodegradation of pollutants is carried out in water volumes of the hydrobotanical zone with a depth of not more than 0.75 m, and when the maximum permissible concentration of pollutants is reached, mud sediments are stirred up within the reach of the roots of eichhoria without water discharge. The number of plants is about 60 plants per 1 square meter. The method is carried out in a turbulent mode. The turbulence of the flow causes the decomposition of bacterial zoogel clusters into tiny colonies, which leads to a rapid increase and updating of the interface and contact between microorganisms and their environment, i.e. there is better contact with contaminants and oxygen dissolved in water. As a result, the rate of supply of food and oxygen to microorganisms increases, and, consequently, cleaning. The degree of purification is: for suspended solids <4.0 mg / l; petroleum products <0.04 mg / l; BOD <5.0 mg O ₂ / L; metal ions - MPC indicators or beyond the threshold of sensitivity of devices. According to observations, already after adaptation, a decrease in permanganate oxidizability by 70-80% and pH equalization were noted. Decreases in the number of Escherichia coli and the total number of bacteria were recorded up to 97% when filtering wastewater and domestic water through the Eichornia biofilter. The total number of saprophytic bacteria in all samples is reduced.

The decrease in TBC (total microbial number) for samples is up to 98%, and the number of OKB (total coliform bacteria) in the process of hydrobotanical cleaning is reduced by 60%, and in some samples by 80%, due to the presence of eichhornia (RF patent No. 2288894 class. C02F 3/32 op. October 21, 2006).

The disadvantage of this method is the incomplete extraction of wastewater from wastewater, which preserves, to one degree or another, the harmful effects of treated wastewater on the environment when they are discharged, and the use of a turbulent mode of movement of the wastewater stream, which leads to sticking and twisting of the roots of eichhoria and, consequently, to a significant reduction in the area of contact of the root system of each bush with sewage, which, accordingly, significantly reduces the amount absorbed by each bush per unit time is harmful x substances. The turbulent flow, due to its considerable speed, in addition, leads to a decrease in the contact time of the root system of each eichornia bush with each volume of moving wastewater. These shortcomings lead either to an increase in water area, including the total length of the canals, which must be sown with eichhoria to achieve the specified quality of treatment, or, while maintaining the area of the canals, to a deterioration in the quality of wastewater treatment, which, in turn, significantly increases the negative impact on the environment from discharge into water bodies or on the relief of insufficiently treated wastewater when implementing the method specified in the known technical solution.

The technical result of the proposed method is the creation of an ecologically closed method of water purification, with the latter being converted into clean water evaporated by the leaves of eichhornium, eliminating the harmful effects of wastewater on the environment after they are neutralized by completely transferring them, with all polluting components, to ecologically clean commercial products, organic fertilizers obtained after composting by known methods of root systems of excess eichornia bushes and organic components Commodity and feed products for animals and birds: the green mass of Eichornia in fresh or dried form.

The specified technical result is achieved in the method of disposal of wastewater. Wastewater is fed through the intake grill to the distribution channel, from where it is distributed along the working channels with eichhornium and maintain their constant level in them. For all operating modes of the canals, the flow rate of wastewater in them does not exceed 5 m / h and the flow is carried out in laminar mode. The process is carried out at an average daily temperature of wastewater 23-30 ° C, an average daily air temperature of 25-35 ° C and at the same time ensure that each bush passes eichhornia, during its growing season (from the moment of its inception to the moment it is removed from the working channel), all water zones the volume of the working channel having different concentrations of pollutants.

Moreover, on the surface of the water in the working channels, the number of eichornia bushes per 1 m ^{2 is} maintained in an amount determined by the formula:

N = K ₁ · (T _sv.v. + T _in. ) ² / T _in. ,

where T _sv - the average daily temperature of wastewater, ° C,

T _century - the average daily temperature, ° C,

K ₁ = 0.96-1.05 - empirical coefficient.

The average daily temperature of air or water is an arithmetic average of the daily fluctuation of air or water temperature.

In addition, the method of wastewater treatment is carried out in the installation for wastewater treatment, which is made of a distribution channel with a receiving grate located above it, and a collection channel of clean water, interconnected by a number of parallel oval-shaped working channels made perpendicular to the distribution channel and the collection to the drainage channel of water and / or placed at an angle to them, provided with transverse movable partitions, with eichornia on the surface of the water, with a width of distribution channel ala, determined by the formula:

A = 1 + K ₂ · n · T _century. / T _sv [m]

where K ₂ = 0.16-0.25 is an empirical coefficient,

n is the number of working channels,

T _century - the average daily temperature, ° C,

T _sv - the average daily temperature of wastewater, ° C,

with the total water surface area of the working channels, determined by the formula:

F = C _s.v. / V _uc. , m ² ,

Where

From _sv - the amount of wastewater received for disposal, m ³ / day,

V _art. - the amount of moisture evaporating from the surface of the leaves of eichornia on 1 m ^{2 the} water surface of the working channels, m ³ / m ² · day, is determined by the formula:

V _art. = K ₃ · [Σ ^0.4 + (T _s.v. + T _c. ) · T _c. / φ] · 10 ^-3 , m ³ / m ² · day,

where K ₃ = 0.98-1.21 is an empirical coefficient,

∑ - the total amount of pollutants in wastewater, mg / DM ³ ,

T _century - the average daily temperature, ° C,

T _sv - the average daily temperature of wastewater, ° C,

φ is the relative humidity of the air,%.

The cross section of the channels has the shape of an inverted trapezoid, with the ratio of the lower base to the upper (0.85-0.95), the side walls are adjacent to the lower base by rounding with a radius of curvature of at least 0.05 m.

If the radius of curvature is less, deposits will form, which, decaying, will themselves pollute the water.

When the ratio of the lower base to the upper is less than 0.85, the channel cross section will approach a conical shape and, when growing, the plant roots will compress each other, worsening their working conditions.

When the ratio of the lower base to the upper is more than 0.95, the upper part of eichornia, the stems and its leaves will compress each other, squeezing the capillaries and worsening the conditions for water circulation through them.

Figure 1 - installation with parallel working channels perpendicular to the distribution channel and prefabricated drainage channel.

Figure 2 - installation with parallel working channels made at an angle to the distribution channel and the prefabricated drainage channel.

Figure 3 - installation with working channels, some of which are perpendicular to the distribution channel and the collection drainage channel, and part at an angle.

Figure 4 is a transverse section of the working channels.

Figure 1 - installation for water purification, which contains a distribution channel 1 with a receiving grill 2, equipped with a shut-off device 3, mounted on the supply line of wastewater 4. Parallel channels 5 are oval, placed perpendicular to the distribution channel 1 and channel 6 with a clean industrial water, in which transverse movable partitions 7 are installed, leaving 2-3 cm in water and protruding 2-3 cm above the water level so that eichhornia is not drifted by the wastewater flow down the channel. The design of the partitions 7 allows you to fix them motionlessly anywhere along the length of the channel 5 or move along the channel 5 together with the bushes of Eichornia. The channels 5 are connected through locking elements 8 to a collection drainage channel 6 of technical water, which, in turn, is connected through a locking device 9 to the drainage line 10 of purified water to technical parameters. All of these channels can be dug in the ground, i.e. the installation is a series of channels placed in a certain way on the ground. This takes into account the terrain. But the installation may be of artificial origin.

Wastewater is fed to a receiving grate 2 (with a hole diameter of 4 mm), on which large particles are retained, after which the wastewater enters the distribution channel 1, and from there it is distributed in laminar mode along the oval parallel working channels 5, where their working level. In the main operating mode, the locking elements 8 and 9 are in the closed state. Locking bodies 8 (all or partially) and 9 are opened only if there is a need for partially purified water for technical needs. In this case, passing through the channels 5, the water flows into the prefabricated drainage channel 6, from where it is discharged to the consumer through the locking member 9 and line 10. To implement the proposed method for the absolute neutralization of wastewater, partitions 7 installed in the working channels 5, without being removed from the channel 5, are periodically moved along the length of the channel 5 so that each eichornia bush visited all areas of the channel with different concentrations of polluting substances.

When the installation is in the main operating mode, the flow rate of wastewater in the working channels 5 (while maintaining the working level of the water volume in the channels 5) from the side of the distribution channel 1 does not exceed, for example, 1-1.5 m / h. When switching to full or partial drainage of water of technical quality and opening the shut-off bodies 8 and 9, the working water level in channels 5 decreases slightly compared to the level in distribution channel 1, which increases the flow velocity, for example, to 4-4.5 m / h, but in all cases this speed should not exceed 5 m / h.

Since in the known method the purification is in a turbulent flow, experiments were carried out.

In the known cleaning method, it is indicated that the implementation of the method is carried out in a turbulent mode of flow, it must be remembered that the root system of each eichhornia bush is a bunch of thin fleecy and very flexible thread-like formations that do not have any rigidity. Therefore, experiments were conducted to purify water in a turbulent mode using eichhornium.

For this, a transparent rectangular vessel with a width of 0.5 m and a length of 3 m was taken, having a cross section in the form of an inverted trapezoid with a ratio of lower base to upper 0.9, through which a stream of water could be recycled at various adjustable set speeds.

In the first series, the vessel was filled with clear transparent water and a large number of experiments were performed at various flow rates. Below are the results of the most characteristic experiments with numbering in the order of presentation (without specifying the serial number in the series).

Experiment 1. In a vessel on the surface of still water, an eichornia bush was placed, fixed so that it remained motionless in one place at any flow rate. At the same time, long fleecy filaments of the bundle-shaped root system of Eichornia were clearly visually viewed separately in the vessel. It is these long, fleecy root threads that allow you to absorb harmful substances from wastewater and process them into plant cell mass that does not harm the environment.

Experiment 2. In the vessel, the movement of water was organized at a speed of 3.6 m / h (1 mm / s). At this speed, the flow regime is laminar. The fleecy filaments of the root system deviated by 2 ° in the direction of flow, but were viewed separately.

Experiment 3. In the vessel, the movement of water was organized at a speed of 5.0 m / h (1.39 mm / s). Threads deviated by 5 °. The flow regime is laminar. All threads of the root system were viewed separately.

Experiment 4. In the vessel, the movement of water was organized at a speed of 36 m / h (10 mm / s). The flow velocity is laminar, but the threads deviated by 15-20 °, while 10-20% of the threads of the root system were intertwined with each other in a single bundle and could not be viewed separately.

Experiment 5. In the vessel, the movement of water was organized at a speed of 360 m / h (100 mm / s). The flow mode is turbulent. All threads deviated by 70-80 ° and were visually viewed as several twisted bundles.

The result of the first series of experiments was the conclusion that the maximum contact area of the surface of the root system of eichhornia with wastewater can be provided at a flow velocity of not more than 5 m / h.

Another series of experiments was performed on the installation described above, filled with wastewater with an initial concentration of pollutants specified in the known technical solution, with the number of eichornia bushes per 1 m ² equal to 60 pcs. The purpose of the experiments was to determine the time of wastewater treatment to the indices specified in the known technical solution, at different speeds of the wastewater flow.

As a result of this series of experiments, it was found that in a turbulent mode of flow, for example, at a speed of 360 m / h (100 mm / s), the time to reach a given residual concentration of pollutants in wastewater was 720 hours.

Under our conditions, i.e. when using the laminar flow regime, the minimum time to reach the required residual concentration of pollutants in wastewater was 320 hours and was recorded at a flow velocity of 4.2 m / h. Values close to this were obtained in the range of wastewater flow rates of not more than 5 m / h.

The maximum degree of purification was achieved in 170-220 hours, it was in this time interval that empirical formulas were determined that allow you to choose those parameters that are necessary to achieve the maximum technical result.

According to the results of a series of experiments, it was found that the optimal number of eichornia bushes on one square meter of the water surface is found and is determined by the empirical formula:

N = K ₁ · (T _sv.v. + T _in. ) ² / T _in.,

where K ₁ = 0.96-1.05 is an empirical coefficient,

T _century - the average daily temperature, ° C,

T _sv - the average daily temperature of wastewater, ° C.

In a known technical solution, the cleaning process proceeds at a constant temperature of at least 19 ° C, i.e. and day and night, plants are exposed to the same temperature of wastewater and air, as well as constant lighting, but eichhornia, like any plant, needs day and night.

In the claimed invention it was found that the lack of lighting at night and the daily fluctuation of these parameters (at least T _s.v. and to a greater extent T _century ) positively affect the rate of absorption of harmful substances from wastewater by eichornia. So, for example, an experiment at an average daily temperature of wastewater T _r.v. = 23 ° С (fluctuation from 19 ° С to 25 ° С) and average daily air temperature Т _в. = 27 ° С (fluctuations from 20 ° С to 35 ° С) showed that the rate of absorption of harmful substances by eichornia in the absence of illumination at night and with daily temperature fluctuations is 21% higher per day than in eichhornia, which grew at constant during days T _dv = 23 ° C, T _century. = 27 ° C and constant illumination.

The subsequent series of experiments were carried out using 2 identical open transparent vessels with a capacity of 10 liters with a horizontal cross-sectional area of 0.15 m ² .

In the first experiment, one vessel was filled with wastewater with a maximum concentration of pollutants specified in a known technical solution. The second vessel was filled with wastewater with a minimum concentration of pollutants specified in a known technical solution. Then, two identical in size and weight of the eichornia bush were selected, weighed and placed in vessels. During this experiment, both vessels were in the same conditions:

T _sv = 23 ° C, T _century. = 27 ° C and φ = 90%.

At the initial stage of the experiment, it was visually established that the eichornia root system initially sorb pollutants from wastewater to its surface, and the maximum size of the sorbed (adhering to the root system threads) visually was observed after 6-7 hours.

After 7 days of experiment, we measured the weight of each eichornia bush (before weighing the root system of the bush is thoroughly washed in clean water) and the amount of water necessary to restore its original level in each vessel.

The results of measurements showed that the weight of the eichornia bush in the first vessel increased by 73%, and in the second - by 18%, while to restore the level in the first vessel it was required to add 1.47 liters, and in the second 0.88 liters. The second experiment was performed under similar conditions, except that after 7 hours the eichornia bushes were swapped.

Measurements taken after 7 days showed that the weight of the eichornia bush in the first vessel increased by 72%, and in the second - by 71%, while to restore the level in the first vessel it was necessary to add 1.44 liters, and in the second - 1, 42 liters.

In this series, a whole series of experiments were carried out at various concentrations of wastewater.

Based on the results of the whole series of experiments, it was concluded that for its optimal life and vegetation, eichhornia tends to “pass through itself” the maximum amount of water with nutrients dissolved in it at an optimal constant concentration for itself. To ensure this, at the initial stage, it absorbs as much as possible all the substances present in the aquatic environment to the surface of its root system, so that in the future, when the concentration of nutrients in the aquatic environment becomes less than that required for it, supplement the required amount from the accumulated on the root volume system. It is necessary to move the eichhorn bushes every 6–9 days using moving partitions, since the channels are oval and the water flow moves clockwise in one channel and counterclockwise in the next channel, then the bushes also move in one place other.

The aim of the next series of experiments was to determine the effect of daily average temperatures of wastewater and atmospheric air on the maximum result obtained in the previous series of experiments.

According to the results of a significant series of experiments, it was found that, with all other things being equal and optimal conditions, the maximum results, with a deviation of 1-2%, were obtained at average daily water temperatures T _s.v. = 23-30 ° C and average daily temperatures of atmospheric air T _century. = 25-35 ° C. A deviation of temperatures from the indicated intervals up or down by 1 ° worsened the result by 5-7%, and each subsequent degree of deviation gave a deterioration of 7-8% compared with the previous one.

The aim of the subsequent series of experiments was to determine the effect of fluctuations of various parameters on the rate of neutralization of wastewater, necessary to determine the required total surface area of the working channels, which, according to the results obtained, should be determined by the empirical formula:

F = C _s.v. / V _uc. , m ² ,

Where

From _sv - the amount of wastewater received for disposal, m ³ / day,

V _art. - the amount of moisture evaporating from the surface of the leaves of eichornia on 1 m ^{2 the} water surface of the working channels, m ³ / m ² · day, and is determined by the formula:

V _art. = K ₃ · [Σ ^0.4 + (T _s.v. + T _c. ) · T _c. / φ] · 10 ^-3 , m ³ / m ² · day,

where: K ₃ = 0.98-1.21 - the empirical coefficient,

∑ - the total amount of pollutants in wastewater, mg / DM ³ ,

T _century - the average daily temperature, ° C,

T _sv - the average daily temperature of wastewater, ° C,

φ is the relative humidity of the air,%,

Example.

Wastewater containing suspended solids with a concentration of 910 mg / L, the amount of BOD is 1000 mg / L, ammonium-containing substances 70 mg / L, nitrite nitrogen 1 mg / L, nitrate nitrogen 5 mg / L, phosphates in terms of phosphorus 14 mg / L ( ∑ = 2000 mg / dm ³ )

Wastewater with a flow rate of 5 m ³ / day through the intake grill was fed into the distribution channel, the width of which is a value determined by the formula:

A = 1 + K ₂ · n · T _century. / T _sv [m]

K ₂ = 0.20, the average daily air temperature T _century. makes 30 ° C and relative humidity of 80%, average daily temperature of sewage T _sv is 25 ° C, n = 8, then the width of the distribution channel should be:

A = 1 + 0.2 · 8 · 30/25 = 2.90 m.

The number of eichornia bushes under these conditions according to the formula will be (K ₁ = 1):

N = K ₁ · (T _s.v. + T _c. ) ² / T _c. ,

N = 1 x ^{(30 + 25) 2/30} = 101 pieces.

For the complete neutralization of these wastewater supplied in the specified amount, the total area of the working channels equal to (K ₃ = 1.1) will be required:

F = C _s.v. / K ₃ · [Σ ^0.4 + (T _s.v. + T _c. ) · T _c. / φ] · 10 ^-3 , m ² ,

F = 5 / 1.1 · [2000 ^0.4 + (25 + 30) · 30/80] · 10 ^-3 = 109 m ² .

Thus, the claimed method allows to neutralize wastewater, eliminating their complete discharge with residual concentrations of pollutants into the environment, while turning them into environmentally friendly commercial products: high-quality organic fertilizers and feed products for animals and birds. Naturally, the proposed method can be implemented in the inventive installation.

Claims (2)

1. The method of disposal of wastewater, which consists in supplying wastewater to the oval-shaped working channels with eichornia and maintaining a constant water level in them, laminar water movement at the same speed in the working channels not more than 5 m / h, with an average daily temperature of 25-35 ° С, average daily temperature of wastewater 23-30 ° С, while ensuring that each bush passes eichhornia during its growing season, all zones of the water volume of the working channel with different concentrations of pollutants and maintenance on the surface of the water Eichhorn bushes in an amount per 1 m ^2, determined according to the formula:
N = K ₁ · (T _s.v + T _in ) ² / T _in ,
where T _{C. in} - the average daily temperature of wastewater, ° C;
T _in - the average daily temperature, ° C;
K ₁ = 0.96-1.05 - empirical coefficient,
and the average daily temperature of air or water is the arithmetic average of the daily fluctuation of air or water temperature. 2. Installation for the disposal of wastewater, characterized in that it is made of a distribution channel with a receiving grate placed above it, and a collection drainage channel interconnected by a number of working channels of an oval shape with eichornia placed perpendicular to the distribution channel and collection drainage channel and / or at an angle to them, equipped with transverse movable partitions, with the width of the distribution channel, determined by the formula:
A = 1 + K ₂ · n · _T / T _SW, [m],
where K ₂ = 0.16-0.25 - empirical coefficient;
n is the number of working channels;
T _in - the average daily temperature, ° C;
T _{C. in} - the average daily temperature of wastewater, ° C,
the cross section of the channels has the shape of an inverted trapezoid, with the ratio of the lower base to the upper (0.85-0.95), the side walls adjoin the lower base by rounding with a radius of curvature of at least 0.05 m, and the total water surface area of the working channels is determined according to the formula:
F = C _s.v / V _is , m ² ,
where C _{S. in} - the amount of wastewater entering the disposal, m ³ / day;
V _IS - the amount of moisture evaporating from the surface of the leaves of eichornia on 1 m ^{2 the} water surface of the working channels, m ³ / m ² · day, and is determined by the formula:
V _IS = K ₃ · [Σ ^0.4 + (T _s.v + T _in ) · T _in / φ] · 10 ^-3 , m ³ / m ² · day,
where K ₃ = 0.98-1.21 - empirical coefficient;
Σ is the total amount of pollutants in wastewater, mg / DM ³ ;
T _in - the average daily temperature, ° C;
T _{C. in} - the average daily temperature of wastewater, ° C;
φ is the relative humidity of the air,%.

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