WO2009058053A1

WO2009058053A1 - Method for disinfecting wastewater and a device for carrying out thereof

Info

Publication number: WO2009058053A1
Application number: PCT/RU2008/000674
Authority: WO
Inventors: Aleksei Vasilyevich Drutsky; Armi Garsiya Lopes; Garsiya Vinsent Lopes; Jliya Alekseevna Drutskaya
Original assignee: Aleksei Vasilyevich Drutsky; Armi Garsiya Lopes; Garsiya Vinsent Lopes; Jliya Alekseevna Drutskaya
Priority date: 2007-10-31
Filing date: 2008-10-29
Publication date: 2009-05-07
Also published as: RU2356855C1

Abstract

The invention relates to wastewater disinfection by using a floating plant Eichhornia crassipes (Water hyacinth) also called Eichhornia or water hyacinth. The inventive method for disinfecting wastewater involves feeding wastewater into a distributing channel and, afterwards, into operating channels, in which water runs in streamline conditions at the same speed equal to or less than 5 m/hour, at the wastewater temperature of 23-30°C and the air temperature of 25-35°C. Simultaneously, the Eichhornia is planted on the water surface in the operating channels in the quantity per one square meter which is determined according to a mathematical formula. The wastewater disinfection method is carried out in a wastewater treatment plant comprising the distributing channel (1) with a receiving grid (2) which is provided with a locking device (3) arranged on the water supply line (4). Parallel channels (5) are arranged in perpendicular position to the distributing channel and a pure water channel and are provided with transversal partitions (6) which are mounted therein in such a way that they are submerged into water at 2-3 cm and projected above a water level at 2-3 cm. Said invention makes it possible to reduce capital input.

Description

The method of wastewater treatment and device for its implementation.

The invention relates to the field of purification of household, industrial and other wastewater using a floating plant Ehoghpia sagassires (Waeg hiipth) - eichhornia or aquatic hyacinth, a representative of higher aquatic vegetation, as a load of artificial or natural hydro-botanical sites.

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, 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 ⁰ C, and the temperature of the nutrient solution in the range from +15 ⁰ C to +36 ⁰ 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, petroleum products 25, phenols 340, suspended solids 1500 with BPK-5 no more than 1000 mg O2 / l and COD no more than 2000 mg O2 / L Plants are additionally artificially illuminated with green-red spectrum lamps with a power of at least 300 W / m2 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 bevel 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 using eichornia as floating in nutrient solution loading 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 not more than 160 mr / l, petroleum products not more than 60 mg / l, phenols not more than 350 mg / l, with MIC not more than 1000 mg Og / l and COD no more than 2200 mg Og / l, with a pH in the range of 5-9 . Vegetation of eichhornia in the hydrobotanical zone is carried out at an ambient temperature 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 reach of Eichornia roots without water discharge. The number of plants is about 60 plants per 1 square meter. The method is carried out in a turbulent mode. Turbulence of the flow causes the decomposition of bacterial zoogel clusters into small 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; BPK <5.0 mg O2 / L; metal ions - MPC indicators or beyond the threshold of sensitivity of devices. According to observations, after adaptation, a decrease was noted permanganate oxidizable ™ at 70-80% and pH equalization. A decrease in the number of Escherichia coli and the total number of bacteria was 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 purification is reduced by 60%, and in some samples by 80%, due to the presence of eichhornia (RF patent Ns 2288894 class C. 02 F 3/32 Op. 21.10.2006).

The disadvantage of this method is the use of a turbulent mode of movement of the wastewater stream, which will lead to adhesion and twisting of the roots of eichhoria, and, consequently, to a significant reduction in the contact area of the root system of each bush with wastewater, which, accordingly, will significantly reduce the amount absorbed by each bush per unit time of harmful substances. The turbulent flow, due to its considerable speed, also 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 to an increase in water area, including the total length of the channels, which must be sown with eichhoria, which, in turn, significantly increases the size of capital investments, including the payback period required to implement the method specified in the known technical solution . The time it takes to obtain the indicated degrees of purification in a known technical solution is 720 hours. The technical result of the proposed method is to reduce capital costs, and therefore the payback period by increasing the rate of echornia absorption of pollutants from wastewater on each square meter of the water surface and, therefore, reducing the time of wastewater treatment when the same indicators are reached for the degree of purification. At the same time, a greater absorption of pollution per unit time by each eichhornia bush increases the rate of growth of its plant mass, which for this method is a useful marketable product, the amount of which reduces the payback period of capital investments.

The specified technical result is achieved in a method for wastewater treatment. Wastewater is supplied to the distribution channel, and then working channels, in which water moves in laminar mode with the same speed of not more than 5 m / h, at a temperature of wastewater 23-3O ⁰ C and air temperature 25-35 ⁰ C.

At the same time on the surface of the water in working channels eichhornia is planted in an amount of 1 square. m, determined by the formula

N = K (Tc.v. + Tv.) ² / Tv.,

where: Tc. at. - average daily temperature of wastewater [ ⁰ C],

TB - average daily air temperature [ ⁰ C],

K - empirical coefficient equal to 0.96-1, 05 pcs. I ⁰ C. The daily average temperature of air or water is the arithmetic average of the daily fluctuation of air or water temperature.

In addition, the wastewater treatment method is carried out in a wastewater treatment plant, 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 working channels made perpendicular to the distribution channel and the channel of pure water and / or placed at an angle to them, equipped with transverse partitions, with eichhoria on the surface of the water with the width of the distribution channel determined by the formula

A = 1 + K - n 'TBV TCB ₁ [M] ₁

where K = 0.16 - 0.25 is an empirical coefficient;

n is the number of working channels;

T ₈ . - average daily air temperature, ⁰ C;

T _c . _c . - average daily temperature of wastewater, ⁰ C

and 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 with a rounding with a radius of curvature of at least 0.05 m. If the radius of curvature is less, deposits will form that will themselves pollute the water.

When the ratio of the lower base to the upper is less than 0.85, the cross section of the channel will approach the cone-shaped and with growth, the roots of the plants will compress each other.

When the ratio of the lower base to the upper is more than 0.95, the upper part of eichhornia, its leaves will compress each other.

Figure 1 installation with working channels perpendicular to the distribution channel and the channel of pure water.

In Fig.2 installation with parallel working channels made at an angle to the distribution channel and the channel of pure water.

On Fig.3 installation with working channels, some of which are perpendicular to the distribution channel and the channel with clean water, and part at an angle.

Figure 4 is a cross 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 locking device 3 mounted on the water supply line 4. Parallel channels 5, placed perpendicular to the distribution channel and the channel with clean water, in which the transverse partitions 6, leaving for water by 2-3 cm and protruding above the water level by 2-3 cm for so that eichhornia is not carried by the sewage flow down the channel, are the channels S connected to the clean water channel? which, in turn, is connected through the shut-off device 8 to the purified water drainage line 9. 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 with a hole diameter of 4-7 mm, on which large particles are retained, after which the water enters the distribution channel 1, and from there it is distributed in laminar mode along parallel working channels. After passing through the channels, water flows into the channel of clean water 7.

Since in the known method the purification takes place 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 flow mode, it must be remembered that the root system of each eichornia bush is a bunch of thin fleecy and very flexible filamentous formations that do not have any rigidity. Therefore, experiments were conducted to purify water in a turbulent mode using eichornia.

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

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 Eichhoria were clearly visually visible in the vessel separately. 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 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 °. Driving mode laminar flow. 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 rate of ZbOhm / hr (10Ohm / s). The flow mode is turbulent. All threads deviated by 70-80 degrees 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 speed of not more than 5 m / h.

In a series of experiments, the time to achieve a certain degree of purification was determined, as it was shown the time to achieve a degree of purification does not depend directly on a number of factors, but is associated with empirical formulas that were obtained as a result of experiments.

The second 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 pieces. The purpose of the experiments consisted in determining the time of wastewater treatment to indicators specified in the known technical solution, at different speeds of the flow.

As a result of this series of experiments, it was found that with a turbulent mode of flow, for example, at its speed equal to ZβOhm / hour (JOmm / sec), 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 equal to 320 hours is recorded at a flow velocity of 4.2 m / h. Values close to this were obtained in the range of flow velocities of not more than 5 m / hac.

A certain 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 a 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 determined by the empirical formula

N = K - (T _c . C. + T _c .) ² / T _c .,

where: K = O, 96 - 1.05 [pcs •% • l / mg] - empirical coefficient; T ₈ . - average daily air temperature, ⁰ C; T _c . - average daily temperature of wastewater, ⁰ C

In a known technical solution, the cleaning process takes place at a constant temperature of at least 19 ⁰ C, i.e., plants are exposed to the same temperature of wastewater and air, as well as constant lighting, day and night, however, eichhoria, like any plant, is necessary both day and night.

In the claimed invention it was found that the lack of illumination at night and the daily fluctuation of these parameters (at least Tv. And mostly Tv) positively affect the rate of absorption of harmful substances from wastewater by eichornia. So, for example, an experiment at the average daily temperature of wastewater Тсв. = 23 ⁰ C (fluctuation from 19 ⁰ C to 25 ⁰ C) and average daily air temperature Tv. = 27 ⁰ C (fluctuation from 2O ⁰ C to 35 ⁰ C) showed that the rate of absorption of harmful substances by eichornia after a month of its growth in the absence of illumination and temperature fluctuations, 21% higher per day than eichhoria growing at constant during the day Tscv. = 23 ⁰ C, Tv. = 27 ⁰ C and constant illumination.

Optimal intervals of values of Tsv. and tv

As a result of this series of experiments, it was found that in order to achieve a technical result, the temperature ranges are as follows:

Tsv. = 23-3O ⁰ C; Tv. = 25-35 ⁰ C. To implement the method, an installation is used that includes a distribution channel, over which a receiving grate is located to trap solids and from which a number of working channels extend. In order for the wastewater speed to be the same in all working channels and to ensure a laminar mode of movement, width A distribution channel should correspond to the value calculated by the empirical formula

A = 1 + K n - T _c / T _c . _in Lm],

where: A - channel width (m)

K = 0.16 - 0.25, [m / unit] - empirical coefficient derived from a series of experiments

T _century ., GS] - the average daily temperature,

Tc _B4 HS] - the average daily temperature of wastewater,

p [unit] - the number of working channels connected to the distribution channel.

Example.

Wastewater containing suspended substances with a concentration of 910 mg / l, the amount of VPK 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. Wastewater through the intake grill was fed into a distribution channel, the width of which is a value determined by the formula:

K = 0.20, the average daily air temperature is 3O ⁰ C, the average daily water temperature is 25 ⁰ C, n = 8, then the width of the distribution channel should be:

A = 1 + 0.2 -8 -30/25 = 2.90 m.

Then the number of eichornia bushes under these conditions according to the formula will be:

N = K (Tc.v. + Tv.) ² / Tv.,

N = 1 ^{"(30 + 25) 2/30} = 101

Thus, the degree of purification achieved in the known method in this case, required 190 hours.

Thus, the claimed method allows you to treat wastewater to the degree of purification of a known technical solution, but in a shorter time, which will lead to lower capital costs and accelerate the payback period. Naturally, the proposed method can be implemented in the inventive installation.

Claims

Claim.

1. The method of wastewater treatment, which consists in the supply of wastewater to the working channels, the laminar movement of water with the same speed in the working channels is not more than 5 m / h, with an average daily temperature of 25-35 ⁰ C and an average daily temperature of wastewater 23-30 ⁰ C and planting on the surface of the water Eichornia in an amount of 1 square. m, determined by the formula

N = K (Tc.v. + Tv.) ² / Tv.,

where: ts.v. - average daily temperature of wastewater [ ⁰ C],

TB - average daily air temperature [ ⁰ C],

K - empirical coefficient equal to 0.96-1, 05 pcs./ ° C

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

2. Installation for wastewater treatment, characterized in that it 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 working channels with eichhorn located U perpendicular to the distribution channel and the channel with clean water and / or at an angle to them, equipped with transverse partitions, with the width of the distribution channel determined by the formula

A = 1 + K n - Tv / Tc.v. , [mj,

K - empirical coefficient equal to 0.16 -0.25

n - number of channels

T - average daily air temperature

T is the average daily water temperature.

and 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)