CN113671109A - Tank type test method for drinking water treatment - Google Patents

Abstract

The invention discloses a tank test method for drinking water treatment, which predicts and controls the pH of the treated water by using a novel particle medium filter and a standardized mixing protocol and titration, shortens the detection time for the application of direct filtration (replacing the traditional sedimentation) by using tank test data, and provides a quick and economic flocculation parameter with the performance of a drinking water treatment plant.

Description

Tank type test method for drinking water treatment

Technical Field

The invention relates to the technical field of water treatment testing, in particular to a tank type testing method for drinking water treatment.

Background

Conventional surface water treatment involves a multi-step process to destabilize the colloidal particles and remove the colloidal particles, as well as dissolved natural organics. This is usually achieved by coagulation [ and rapid mixing ], flocculation [ or gentle mixing ], precipitation and filtration. A coagulant/flocculant, usually a metal salt, is added to the raw water supply prior to rapid mixing to aid in the removal of contaminants. It is very important to optimize the coagulation conditions in the treatment plant in order to maximize the treatment efficiency, reduce the running cost, and minimize the concentration of residual metals in the product water.

The tank test is one of the most common tools used by water treatment facilities to determine the treatment conditions required to achieve a finished water target. Traditional pot tests, i.e. using precipitation as the main particle removal mechanism, have proven to be unsuitable for certain types of water. This is particularly true for low turbidity bodies of water where the lower chance of contact prevents the formation of settleable flocks. Floc refers to the formation of particles between aluminum hydroxide and particle contaminants that occur after alum addition during drinking water treatment. There is a need to develop a process that is useful in all processing facilities and provides results that better demonstrate effective coagulation conditions.

Disclosure of Invention

The invention aims to provide a tank type test method for drinking water treatment, which aims to improve the treatment efficiency, reduce the operation cost, reduce the concentration of residual metals in finished water to the maximum extent and optimize the coagulation condition of a treatment plant.

In order to achieve the purpose, the invention adopts the following technical scheme:

a tank test method for drinking water treatment, characterized in that it comprises the following steps:

s1, initial setup and titration method: raw water was collected and kaolin was incorporated as granules into each pot;

s2, preparing flocculant dosage: fill the flocculant dose per jar into a syringe [ BD Leur-Lok^TM[ 1 ] to (1);

s3, a jar test method and a particle removal mechanism, wherein the particles are removed by adopting a combination of precipitation and filtration.

Preferably, S1 includes the steps of:

s101, collecting 2.2L of raw water and adding the raw water into each tank;

the jar tester was turned on and set to continue mixing at 100 rpm;

kaolin was then incorporated into each jar as a particle/turbulence source as a first step in creating consistent and repeatable synthetic water.

The concentration of the flocculant used was 10g/L, the holding time was 30 days, and hydrochloric acid or sodium hydroxide having a concentration of 0.1N was used to control the flocculation pH of each tank during the test.

To determine the amount of pH control solution required for a given flocculant dose, each tank must be titrated;

the pH value used in the test period is in the range of 5.0-8.0, and the increment is 0.5 unit;

approximately 10mL of water was wasted from the bottle before 200mL of sample was collected in a 250mL glass beaker and placed on a stir plate with a magnetic stir bar, pH was monitored using a pH meter and pH probe, and quasi-results were previously cleared;

the pH of the sample was obtained and recorded as the raw water pH,

then, taking out the pH probe from the sample, adding the dosage of the flocculating agent, changing the pH probe after the numerical value is stable, recording the pH value after flocculation, then adding a necessary pH regulator into the flocculated sample by a micropipette in increments of 0.01-1 mL until a target pH value is obtained, and recording the volume of the pH regulator and the final pH value;

at this point, 40mL of turbidity sample was collected from each jar in a circular turbidity cell, turbidity was measured using a turbidimeter [ Hach 2100AN ], a timer was started once the cells were placed in the turbidimeter and the reading was allowed to stabilize for 30 seconds, at the end of this stabilization period the lowest turbidity reading in the next 5 seconds was recorded as the initial turbidity.

Preferably, S2 includes the steps of:

s201, filling the dosage of flocculant for each tank into a syringe, the first step of filling the syringe is to remove the plunger and cover it to prevent loss of flocculant, move flocculant from the stock solution into the syringe, replace the plunger, invert the syringe, remove the cover, and then depress the plunger to push out the air in the syringe, ensuring that no flocculant is dispensed, each syringe being secured to the corresponding tank by a strip of hook and loop fastening tape.

Preferably, S3 includes the steps of:

s301, the jar test method includes a 1min rapid mix cycle at 300rpm [ G609S-1 ], after the jar test method is initiated, a flocculant is injected into each jar immediately, after the rapid mix stage is complete, 200mL of sample is collected from each jar, the pH is measured and recorded as the flocculation pH, the goal is to fix this value within 0.2 units of the target pH;

after rapid mixing, there is a period of float cracking, after flocculation, there is a particulate removal stage, including settling, filtration and a combination of the two;

when the device is used, the settling time is 20min, after the flocculation period is finished, the slurry is taken out of the tanks, after the settling period is finished, 10mL of slurry is wasted from each tank, and turbidity samples are collected;

filtration requires continued stirring at the same intensity as at the end of the flocculation period, and after collection of the flocculated pH sample, the filter is connected to a tank. The valves on the jars were opened at 15 second intervals from the end of flocculation, this interval being to ensure that turbidity samples could be collected at the same point during filtration in each jar, allowing a total volume of 800mL of water to flow through the filter, once the water level in the jar reached the 1000mL mark in the jar, collecting and measuring the filtered turbidity samples, after the end of the settling period [ 20min ], allowing 800mL of settled water to flow through the filter without mechanical mixing, then collecting turbidity samples and analyzing;

once the final turbidity samples were collected and recorded, final pH and temperature values were obtained as a means of quality control and to enable researchers to monitor the conditions of the jars to ensure consistency from one test to another.

Compared with the prior art, the invention provides a tank type test method for drinking water treatment, which has the following beneficial effects:

the method can be used in all water treatment facilities, improves the treatment efficiency to the maximum extent, reduces the operation cost, reduces the concentration of residual metal in finished product water to the maximum extent, and optimizes the coagulation condition of a treatment plant.

Drawings

FIG. 1 is a Shimadzu TOC-L calibration curve

FIG. 2 is a schematic diagram of a PDA device.

FIG. 3 is a schematic view of a depth filtration device.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

Referring to fig. 1-3, a canister test method for drinking water treatment utilizes six waters in order to develop a new filter canister test method. These include 4 synthetic waters and 2 natural waters. In the experiment at each stage, not all the water areas are used, and these water areas are identified and, if necessary, may be used throughout.

Model waters were developed and controlled for turbidity, alkalinity, TOC and SUVA by addition of various products. Kaolin is added as a source of turbidity/particles. The kaolin particles have a size of 0.1-4 μm. The stock solution has a concentration of 5 g/l and alkalinity is added in the form of sodium bicarbonate to provide a certain buffer capacity for each water. Instant coffee and liquid fertilizer (2% solution). The liquid fertilizer is a preheated and fulvic acid concentrate consisting of 17% preheated acid, 13% fulvic acid and 4% preheated acid obtained from Leonardite shale. Medium turbidity/DOC/SUVA model water was initially bench-top tested in 2.2L batches in individual cans, but later a batch process (26.4L) was used in which kaolin was added to the cans alone. When water is synthesized singly or in large quantity, attention is paid. The model batch was the water area used for the experiment within 24 hours.

The raw water UV-254 absorption was measured with an ultraviolet-visible spectrophotometer. The ultraviolet cell used was a standard quartz cuvette with a light path of 1 cm. Raw water samples were collected in 30mL glass syringes. The sample was carefully filtered through a 0.4 micron polycarbonate membrane. The filter membrane was placed in a 25 mm filter holder with a pair of forceps to ensure that the membrane was properly positioned without damage. The filter holder was attached to a syringe and the plunger was depressed with sufficient pressure to push the sample through the membrane. The water was filtered directly into an autoclaved amber 40mL round bottle. After the sample filtration was completed, the membrane was examined to verify that no damage or complications that could affect the quality of the sample occurred during this process.

The instrument was zeroed using ultrapure water prior to uv absorption analysis. Before zeroing and between each reading, the uv cell was wiped with a lint-free cloth and then with a piece of lensed paper. The "Q" on the cell is always placed facing the tube module. After zeroing, the cuvette was filled with raw water and placed back into the sample cell holder in the same direction as when zeroing. Three measurements were made for each sample and verified to be in compliance with the instrument specifications. The lowest of the three readings was recorded. The sample was disposed of and the sample cell was rinsed with ultra pure water before running another sample. There was no verification that the sample bottles and filtration equipment used during the TOC test were contaminated with sample. The DOC of the sample was measured by uv analysis. The dissolved organic carbon was measured using an organic carbon analyzer. The instrument follows standard method 5310b. A calibration curve is created using a calibration curve guide. The standard was produced using an automatic dilution of 10 mg DOC/L stock solution.

Before DOC analysis of the raw water sample, two runs were performed with ultrapure water. After all the raw water samples were measured, an additional ultrapure water cleaning cycle was performed. These are all to ensure that the instrument is not contaminated by previous measurements.

As previously mentioned, several different flocculation protocols were analyzed during the study. A photometric dispersion analyzer was used to evaluate how varying the flocculation method affects floc size. The mixing intensities used during the analysis were 24, 36, 50, 80, 115 and 174s^-1. These G values correspond to flocculation at 30, 40, 50, 70, 90 and 120rpm on the cans. The test was carried out in a test instrument with 1.8L of water at a temperature of 20 ℃. This temperature is assumed and is used for calculation purposes only.

PDA 2000 was used to monitor flotation growth rate and peak flocculation size during flotation analysis. The premises of the PDA theory were discussed elsewhere previously. Polymerization is monitored in cells flowing continuously as the light beam from the high intensity LED is directed through the cell. The light transmitted through the coagulated sample is measured by a photodiode and the signal is converted to a voltage proportional to the intensity. The a.c. component of the voltage signal is amplified and signal fluctuations are measured. Amplification allows to check <1mV fluctuation in the 10V signal. The PDA 2000 found the RMS of the a.c signal, the ratio of RMS to d.c voltage (FI) to be the output for the monitoring of blisters. Particle polymerization results in an increase in FI. Throughout the experiment, the RMS rise was set to 0.80 and the d.c rise to 5.00. The electronic filter of the PDA was turned on during all monitoring. The filter uses data that is on average spaced 5s apart, allowing for a smoother output signal.

During PDA analysis, mixing was performed using an overhead mixer with a 3.4 "hydrofoil impeller. LabView software was used to control the mixing and recording of PDA data. Automation of the mixing process allows for consistent transitions between the various stages of the flocculation process. A USB data acquisition module was used to communicate between the peripheral and the LabView method.

A support jack (BrandTech Scientific Inc.) was used to ensure that the hydrohead during the flocculation test matched the hydrohead of the bench tank test to provide a similar filtration load rate. One pot (Phipps)&Bird^TM

) Sample tap and oneA constant diameter tee junction with 1/4"ID polyethylene opaque tubing. One sample valve was connected to a manifold (3/8 "polyethylene tubing with push-in ball valve). Tubing from the tee to the PDA instrument (b) ((b))

15 a 60F) using 1/8"id tubing(s) at the flow cell

R-3603), and then transitioning to 3/16' inner diameter silicone tube (

15 a 60F). Using a peristaltic pump with computer drive (Cole-Parmer Instrument Company,

model 7550-10) and Pump head (

Easy Load, Model 7518-02) for flow cycling.

Each test included 609s^-1One min flash mix of intensity (300 rpm, 2 liters of water @20 ℃) and a single stage flocculation of 10 min. Two cone flocculation methods were evaluated. Conical flocculation consists of 3 stages, the first 2 stages having a duration of 5min and the last 10 min. Mixed bowel (RMS velocity gradient) 80s^-1First stage of (2), 50s^-1And 24s, and^-1in the first run of staged flocculation experiments. In the second conical flocculation experiment, the mixing intensity of the first, second and third stages is 174, 155 and 80s respectively^-1. Single stage mixing intensities 174 and 24s^-1The particle removal efficiency of (a) was evaluated by filtration in a manner similar to that applied to the jar test method, respectively. Filtration analysis A dose of 5.0mg/L alum coagulant was selected under 2 different treatment conditions to simulate flocculation by charge neutralization coagulation mechanism, with a target coagulation pH of 5.0. The target coagulation pH value is 7.0 under the condition of sweeping flocculation, and the dosage of the coagulant alum is 50 mg/L.After preliminary testing, 174s^-1Single stage and first cone-flocculation (80 s)^-1Is the first stage, 50s^-1For the second stage, 24s-1 for the last stage) method was evaluated using the full tank test method for flocculation time described previously. All flocculation analyses were performed with medium turbidity/DOC/SUVA model water. Before starting each flocculation test, the tank was filled with 2.3L model water and kaolin was added to achieve the desired turbidity. In this process, the mixing speed was set at 160rpm (120 s)^-1) Manual control of the LabView method was used. The main valve on the can is then opened. About 10mL of water was wasted through the sample tap and 200mL of sample was collected. Titration was performed in the same manner as the benchtop method to determine the appropriate chemical dose. The initial temperature was also measured. A 40mL turbidity sample was collected, measured and recorded. Before adding a predetermined volume of pH adjusting chemical, it is necessary to ensure that the water level is at the 2L mark on the jar. And after the pH value is adjusted, draining the pump. After the pump is filled, the pump is started by a LabView method through connection with a VFD relay. The flow rate was preset at 20 mL/min. The PDA instrument was turned on and the gain was set (RMS 80, dc 5.0). Preparing coagulant doses and using pipettor

2-10mL Finnpipette). The required flocculation parameters were entered into the process and the mixer was removed from the manual mode. After the flocculation process was initiated, flash mixing was initiated and administered at a dose of 1-1.5 mL. After one min, the coagulant is added. After the flash mixing was complete, a 200ml pH sample was collected and the pH after coagulation was recorded. If filtration is required, the filter is connected at this point. At the end of the desired time period, the data collection and stirrer was stopped. Filtration required an additional flocculation time of 5min, but the additional data was omitted from the analysis. Final pH and temperature data were collected after the test was completed.

On a laboratory scale deep bed filtration apparatus, 18 inch Vitro was used

Filter media versus filtration load rate and filtration turbidityThe relationship between them was preliminarily evaluated. The filter was constructed from 2 inch clear No. 40 PVC. The flow through the apparatus was controlled by a 0.5h.p. motor and pump head, and the drive was controlled using an a/C frequency converter. Flow was monitored with an on-line flow meter and verified manually using a graduated cylinder.

Raw water was treated in 15L batches in a 5 gallon bucket. Use of an overhead stirrer (Caframo) with a 4.5' hydrofoil impeller^TMStirrer BDC 2002). The mixing intensity was the same as that of the pot tester. Fast mixing for 609s^-1G value (578RPM) was 1 min. Cone flocculation was performed with stirring intensity of 80(149RPM), 50(106RPM) and 24s-1(RPM) for 5, 5 and 10min, respectively. At the end of the flocculation stage, stirring was continued and filtration was started.

The setup and experiments of the filter load rate test performed on the bench followed the canister test method of section 3.2. Using 5/16 'tubes with internal diameter reduced to 1/8' (D)

R-3603) a modified filter outlet pipe was constructed. These tubes were used for filters No. 2-6. The sewage tip was 2 tube-to-tube barb connectors (1/8"ID), 2 tube-to-tube reducer (1/8" ID × 1/16"ID), and a needle (BD) with 18 gauge

) Syringe tip (BD)

). The flow of tanks 2, 3 and 5 was reduced by attaching the insulating sheath of the copper wire to the sewage nozzle using a two-component epoxy. Canister 4 is an unmodified reducer and canister 6 uses a needle. Titration is an important step of the new jar test method. Alum is an acidic substance and when treated with alum, only the path of potential treatment conditions goes diagonally in a two-dimensional area. An example can be seen in the figure, where a titration curve is plotted against alum alone. It can be observed that increasing alum dose will be accompanied by a simultaneous increase in alum doseTwo coagulation variables (coagulant amount and coagulation pH) were varied. The alum treatment only limited the treatment range to one area where the sweep flocculation was predominant. It is necessary to adjust the coagulation pH in order to assess the treatment potential in other areas of the operating map. The main difference between the new tank test method and the previous method is the suggestion to optimize the two coagulation variables independently. During the jar test, titration is required for each jar to determine the amount of acid or base required to reach the target coagulation pH. No coagulant was added during titration. The lowest target pH (5.5) required the addition of the largest volume of acid (1.35mL) to 200mL of water sample. The pH of the raw water was always between 8.0 and 8.5.

Titration curves for model water No. 2 at an alum dose of 30 mg/L. Coagulation pH after alum addition to a 200mL beaker. In the data obtained, the average coagulation pH during titration was 6.65. For this set of titrations, it is necessary to add either an acid or a base according to the target pH (i.e. when the coagulation pH > target pH). This is shown on the titration curve as the slope is negative when acid (0.1N HCl) is used as titrant and positive when the sample is titrated with base (0.1N NaOH). In this set of data, the acid is the titrant at the inflection point.

Sample No. 2 water a summary of the titrant volumes required for a series of pot tests to reach the target pH.

The purpose of filter loading optimization was to evaluate the effect of filter loading on filtration turbidity. An optimal filter loading rate will result in identifying favorable coagulation conditions without falsely identifying suboptimal conditions as valid conditions. Other objectives were to determine the appropriate media depth and volume for the canister test filter unit.

Preliminary testing of the relationship between filtration load rate and treated water quality was conducted on a filtration unit containing 18 inches of media. The filter media is the same as that described above for the table filtration apparatus. The water used in the experiment was model No. 1 water. The filtration load rates tested were 4.76gpm/ft2, 2.86gpm/ft2, and 0.46gpm/ft 2. The tests were carried out at coagulation pH values of 5.5 and 6.5. Generally, at a target coagulation pH of 5.5 (which is suboptimal from a turbidity removal perspective), reducing filtration duty can result in reduced filtration turbidity. At a target coagulation pH of 6.5, it was observed that the filtration load rate had little effect on the filtration turbidity under more favorable coagulation conditions.

After the initial test, the filtration load rate was evaluated on the bench with model water No. 1 on a jar test rig and 3 inches of filter media. This filter media depth allows for sufficient filter volume for backwash and filter headspace without the need to build a filter that is larger than the volume of water available for filtration. The load rates evaluated were 4.65gpm/ft2, 2.46gpm/ft2, 2.14gpm/ft2, 1.43gpm/ft2, 0.86gpm/ft2, and 0.36gpm/ft 2. The tests were again carried out at coagulation pH values of 5.5 and 6.5. Results are reported as filtration turbidity and turbidity removal rate. It was observed that the filtration turbidity was 0.98NTU at a filtration load rate of 0.36gpm/ft2 for alum at a coagulation pH of 5.5 and a coagulant dose of 5 mg/L. When the coagulant dosage is 5mg/L as alum, the filtration turbidity at all other flow rates is between 1.58 and 1.74 NTU. The turbidity removal rate is reduced by about 20-30%.

At a target set pH of 5.5, the filtration performance on the scale apparatus was lower than the depth filtration apparatus, and filtration turbidity increased as the filtration depth was reduced from 18 inches of media to 3 inches. This indicates that the filter design can result in low filtration turbidity when the coagulation conditions are poor. This is problematic when the goal of the tank test is to determine the optimum pH and coagulant combination for coagulation conditions.

The effect of filtration load rate on turbidity removal rate was also evaluated at a coagulation pH of 6.5. Changing the filtration duty had no significant effect on turbidity removal.

When the coagulation pH value is 6.5, the treatment efficiency is improved as compared with that when the coagulation pH value is 5.5. This may be due to coagulation efficiency; since the particle removal rate is increased due to the improvement of the coagulation effect, the influence of the filter loading rate on the turbidity of the filtration is reduced. There was no significant difference between filter loading at the coagulation pH target of 6.5. Based on these results, a filter loading of 4.65gpm/ft2 was selected because it was able to be effectively processed through the canister test filtration unit in the shortest amount of time. In addition, the effect of the change in loading rate between canisters on the filtration results should be minimal. This is especially true when the processing efficiency is highest, which is precisely the condition to be determined by the method.

It was observed that the hypothetical tank tests performed at an initial coagulation pH of 6.5 or 7.0 resulted in a coagulant dose and coagulation pH combination that belonged to the maximum observed turbidity removal zone for all waters evaluated except model water # 3. All three hypothetical tank tests for this model water resulted in the same flocculant dose (30 mg/l) and coagulation pH (6.25) combination, which was outside the maximum turbidity removal region observed.

The area of maximum observed turbidity removal efficiency was greater than or equal to 80%. The selected effective solidification conditions are in this region. From a previous series of jar tests, the alum dose and measured set pH number for each jar were plotted against a profile. Each jar test is numerically labeled in order of execution. The maximum percent turbidity removal observed did not exceed the 95% threshold used in the previous profile. This is due in part to the low turbidity of the raw water (turbidity ═ 1.66 NTU).

The method is developed and applied to the alternating and single variable optimization method of low-turbidity and medium-high DOC/SUVA type water. Using this optimization method, an effective processing region is identified that matches a subsequently created contour map. It was also observed that the use of percent turbidity removal as an indicator to assess the therapeutic effect was dependent on raw water turbidity, which resulted in different turbidity removal targets.

Stimulation is an important step in the new can test method when optimizing the coagulation variables (coagulant dose and coagulation pH). Titration prior to jar testing may ensure that the target clotting conditions are met during bench-top evaluation. The use of titration allows a specific coagulation pH to be maintained in all jars, or different target pH values to be accurately assessed in each jar during jar testing. Adjustment of the amount of coagulant and coagulation pH is sometimes a necessary condition to achieve optimal therapeutic conditions. When water is treated with alum alone, the addition of an acidic coagulant results in simultaneous changes in pH and coagulant dosage. This provides only one diagonal path for treatment across a two-dimensional area, sometimes ignoring the optimal treatment area altogether. Filtration through 3 inch granular media at a filter loading rate of ≈ 5gpm/ft2 is sufficient for freeze optimization through canister testing while reducing test time. The results show that filter loading and filter design only affect tank test results when the freeze conditions are below the optimum level. The low filter loading and deep bed filter resulted in increased turbidity removal under sub-optimal coagulation conditions. However, the purpose of the canister test is to distinguish between relatively good and poor treatments, and having a highly effective filter will make the distinction between these two conditions more difficult and inaccurate. Monolayer stage flotation at 120rpm provided sufficient flocculation growth for tank testing, directly filtering the waters and treatment conditions examined in this study. Comparing the tank test results for the hollisan and canaborisshan natural waters with the overall solidification conditions for each facility, the results show that the new filtration-based tank test method better predicts actual plant performance than the traditional settling method. The pot test results were plotted using an outline map to help identify areas of coagulation conditions that could be applied to a plant scale. The results of the alternating, univariate optimization method are influenced by the initial flocculant dose and pH. Starting from a pH of 6.0 to 6.5, different flocculants amounts and pH recommendations may be generated. Using a pH median of 6.5 at the start of a series of optimized jar tests, a pH and coagulant dose combination was generated within the maximum turbidity removal zone of the waters and treatment conditions examined in this study.

Claims (4)

1. A tank test method for drinking water treatment, characterized in that it comprises the following steps:

s1, initial setup and titration method: raw water was collected and kaolin was incorporated as granules into each pot;

s2, preparing flocculant dosage: fill the flocculant dose per jar into a syringe [ BD Leur-Lok^TM[ 1 ] to (1);

s3, a jar test method and a particle removal mechanism, wherein the particles are removed by adopting a combination of precipitation and filtration.

2. The tank test method for drinking water treatment according to claim 1, wherein S1 includes the steps of:

s101, collecting 2.2L of raw water and adding the raw water into each tank;

the jar tester was turned on and set to continue mixing at 100 rpm;

kaolin was then incorporated into each jar as a particle/turbulence source as a first step in creating consistent and repeatable synthetic water.

The concentration of the flocculant used was 10g/L, the holding time was 30 days, and hydrochloric acid or sodium hydroxide having a concentration of 0.1N was used to control the flocculation pH of each tank during the test.

To determine the amount of pH control solution required for a given flocculant dose, each tank must be titrated;

the pH value used in the test period is in the range of 5.0-8.0, and the increment is 0.5 unit;

approximately 10mL of water was wasted from the bottle before 200mL of sample was collected in a 250mL glass beaker and placed on a stir plate with a magnetic stir bar, pH was monitored using a pH meter and pH probe, and quasi-results were previously cleared;

the pH of the sample was obtained and recorded as the raw water pH,

then, taking out the pH probe from the sample, adding the dosage of the flocculating agent, changing the pH probe after the numerical value is stable, recording the pH value after flocculation, then adding a necessary pH regulator into the flocculated sample by a micropipette in increments of 0.01-1 mL until a target pH value is obtained, and recording the volume of the pH regulator and the final pH value;

at this point, 40mL of turbidity sample was collected from each jar in a circular turbidity cell, turbidity was measured using a turbidimeter [ Hach 2100AN ], a timer was started once the cells were placed in the turbidimeter and the reading was allowed to stabilize for 30 seconds, at the end of this stabilization period the lowest turbidity reading in the next 5 seconds was recorded as the initial turbidity.

3. The tank test method for drinking water treatment according to claim 1, wherein S2 includes the steps of:

s201, filling the dosage of flocculant for each tank into a syringe, the first step of filling the syringe is to remove the plunger and cover it to prevent loss of flocculant, move flocculant from the stock solution into the syringe, replace the plunger, invert the syringe, remove the cover, and then depress the plunger to push out the air in the syringe, ensuring that no flocculant is dispensed, each syringe being secured to the corresponding tank by a strip of hook and loop fastening tape.

4. The tank test method for drinking water treatment according to claim 1, wherein S3 includes the steps of:

s301 pot test method includes 300rpm [ G ═ 609S^-11min fast mix cycle, flocculant was injected into each tank immediately after the tank test method started, 200mL samples were collected from each tank after the fast mix stage was completed, the pH was measured and recorded as the flocculation pH, the goal was to fix this value within 0.2 units of the target pH;

after rapid mixing, there is a period of float cracking, after flocculation, there is a particulate removal stage, including settling, filtration and a combination of the two;

when the device is used, the settling time is 20min, after the flocculation period is finished, the slurry is taken out of the tanks, after the settling period is finished, 10mL of slurry is wasted from each tank, and turbidity samples are collected;

the filtration requires continued stirring, with the same intensity as at the end of the flocculation period, after the flocculated pH sample is collected, the filter is connected to the tank, the valves on the tanks are opened at 15 second intervals from the end of flocculation, this interval is to ensure that during the filtration process in each tank, the turbidity sample can be collected at the same point, the total volume of water allowed to flow through the filter is 800mL, once the water level in the tank reaches the 1000mL mark in the tank, the filtered turbidity sample is collected and measured, after the end of the settling period [ 20min ], 800mL of settled water is allowed to flow through the filter without mechanical mixing, then the turbidity sample is collected and analyzed;

once the final turbidity samples were collected and recorded, final pH and temperature values were obtained as a means of quality control and to enable researchers to monitor the conditions of the jars to ensure consistency from one test to another.

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