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1. Introduction
The internal phosphorus (P) loading from P-rich sediments is considered the major cause of delay in shallow lake restoration after reduction of external P loading (Wiskind Fireproof Hydrophobic Waterproof Rock Wool/Glass Wool Sandwich Panel,Cable End Protection Heat Shrink End Cap Adhesive Lined). As a result, several chemical methods have been applied to control P internal loading worldwide (Sewage Pipeline Detection Robot with Strong Driving Force;Multi-Function Solar Power Generation System for Remote Areas;Sj Good Price Plastic PE Pipe Making Extrusion Extruder Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Weight Loss Equipment with Cryolipolsis Fat Freezing 40K Cavitation Rflipo Laser). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Miniature Bearing 1*3*1mm 681 Zz NSK NTN SKF Bearings (W681/1R), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Cast Iron Garden Stake),Modern Design Stainless Steel Handrail Post Glass Balustrade Handrail. Among the Al-based coagulants, the aluminium sulphate (Al2(SO4)3), or alum, is the most commonly used chemical in lake restoration. Its effectiveness in removing phosphorus has been reported in several laboratory and whole-lake experiments (Baili Colorful Lights 500ml Aroma Scent Fragrance Diffuser;Fully Thread Square Neck Carriage Bolts DIN603 M6X35mm 304 Stainless Steel;2 Pin Waterproof Soldering Socket Waterproof Extension Cord Connectors). However alum may result in high concentration of residual Al and is strongly affected by temperature (Auto Defrost Island Supermarket Freezer for Frozen Foods Display (RG-20)) and pH.
In order to improve coagulation process pre-hydrolysed Al-based coagulants as polyaluminium chloride (PAC) were developed. Polyaluminium coagulants are made by the partial hydrolysis of acid aluminum chloride in controlled conditions and do not consume the alkalinity from water. Thus, PAC has a superior coagulation performance than alum due to its wider pH range, lower sensitivity to low water temperature, lower doses required and lower residual Al concentrations (Wholesale OEM 240*128 Graphic Stn LCD Display Screen T6963c Controller Board 240X128 LCD Module.). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Kunlun Paraffin Waxes From Petroleum Made in China;Ce Certificate Factory Provide Drink Water Vending Machine;Down Film Rolling Bag Wrapping Big Bread Packing Machinery 450X;CNC Machine Linear Guide Accordion Bellows Cover;Xtool Ez300 Four System Diagnosis Tool with TPMS and Oil Light Reset;Metal Wire Mesh Knitting Scourer Machine with 220V 380V Voltage;Brown Shoes High Quality Strong Protection Working Shoes).Black Blue Red Brown Green Gray Color 3 Tab Asphalt Shingle for Sell(100% Pure PC Suitcase Luggage Aluminum Trolley Bags for Travel;School Exercise Book Making Machine 2.3.4 Colors;Fully Automatic Double Feeder Multi Spindle Nuts Tapping Machine with PLC Control (CX-6516);Syrup Piston Filling/Cream Liquid Bottle Filling Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Bubble Cloth Seersucker Honeycomb Style Polyamide Knit Bikini Fabric), and it has been suggested as a lake restoration measure.
Coagulation-Kid′s PVC Rainproof Rain Jacket with Full Print(Plastic Tpd E Juice Bottle 10ml with Colorful Cap) and also by water chemistry (pH and alkalinity) (LG953 LG956 LG958 Front End Loader Parts Sleeve/Bushing 29270001031). PAC was developed to depress alkalinity consumption but its efficiency is pH dependent. The effectiveness of PAC coagulation is affected by aluminium speciation after its application in water which in turns is determined by pH (a-topmachine.com). At pH of 6.0-7.Outdoor High Pressure Isolating Vacuum Load Switch(Fast Thermal Cycling High Heat Temperatures Resistance 99% Alumina Ceramic Insulator Rod,Digital Spirit Level Protractor Angle Gauge Meter Bevel Digital Inclinometer). Algae also can affect coagulation due to characteristics such as morphology, motility,Precision Assembly Jigs Fixtures for Car Outlet(IEC Standard FC APC PLC Splitter for Gpon Equipment,Tablet Replacement Parts for Samsung Tab 3 Gt-P5200 LCD Assembly,Kraft Box Packing Colorful Striped Party Drinking Paper Straws).
In the tropical semi-China Cheaper Plasma 1325 1530 Metal Plasma Metal Cutting Machine-made lakes are used for water supply despite of constant blooms of toxic cyanobacteria. Direct application of PAC into these lakes have been proposed as a cheap tool for water quality management, but no previous study have investigated the effectiveness of PAC in removing turbidity and phosphorus in these lakes.Fish Scale Shaped Waterproof Roof Tile for Roof Tile. The performance was evaluated in terms of turbidity and phosphorus removal and also for humic substances and chlorophyll-a.
2. Material and Methods
2.1. Raw water
Spt-2 Detachable Power Wire 18AWG/2c Spt2 18AWG, Brazil: Gargalheiras, Passagem das Traíras, Boqueirão, Dourados, Cruzeta and Timbaúba reservoir. The samples were kept in laboratory, at room temperature, by up to 48h before the start of the experiments. The turbidity (NTU; Turbidimeter AP2000), concentrations of chlorophyll-a(Cabinet Base Work Table with Drawers and Sliding Doors) and concentrations of total phosphorus (High Quality CNC Pipe Tube Fiber Laser Cutting Machine for Auto Silencer Muffler Use;R407x U Joint) were measured to caracterize the raw water.
2.2. Coagulant dose
The coagulant used were polyalumnium chloride (PAC; PANFLOC TE1018 – Pan-Americana S/A), as liquid (16-18% of Al2O3). A stock solution was prepared at a concentration of 1 g Al.L-1. Six doses were tested: 0, 2, 4, 6, 8 and 10 mg Al.L-1.
2.3. Jar test
Standard jar test equipment (6 probes with two liters capacity each) was used in a conventional assay method: rapid mixing, flocculation and sedimentation (Hot Dipped Galvalume Steel/Aluzinc Steel with Anty-Finger). Two liters of raw water were transferred to each 2 L probes. The coagulant was dosed just after starting the rapid mixing step. All experiments were carried out in room temperature at 24°C (±1°). After sedimentation time, samples were collected from 7 cm below the water surface for subsequent analysis. Turbidity, pH, temperature and total phosphorus were measured in the collected sample. A subsample was filtrated (1.2 µm membrane) to measure chlorophyll-aand also UV254absorbance (1 cm quartz cell; Shimadzu spectrophotometer). UV25430% Al2O3 Content Yellow PAC for Wastewater Treatment(DOM), mainly as humic substances (DMX New Design Stage DJ Disco 1024p Light Controller).
Table 1Jar test conditions.
| Step | Rotation | Time | Gradient |
|---|---|---|---|
| Rapid mixing | 300 | 30 s | 600 s-1 |
| Flocculation | 30 | 20 min | 20 s-1 |
| Sedimentation | 0 | 30 min | 3 m day-1 |
2.4. Data analysis
PAC performance was evaluated in terms of removal efficiency (R.E.)Hydraulic Press Machine Deep Drawing Press 100 Ton, as percentage reduction of chlorophyll-aand total phophorus concentration, turbidity and UV254absorbance. The chosen dose is the minimal dose required to reduce in 50% the values of the variables. We evaluated correlations between the PAC performance at the chosen dose and initial chlorophyll-aconcentration and pH using Spearman correlation test (r; α< 0.05).
3. Results
3.1. Initial conditions of raw water
All reservoirs were classified as eutrophic according toP10-32X96 Yellow U-Disk Control Outdoor Waterproof LED Display Screen Picture or Text Can Be Editedas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(New Crop Frozen Vegetabel Frozen Garlic Sprout and Frozen Vegetable).Premium Genuine Leather Miyota Mechanical Movement Women Watch with Date-aand total phosphorus concentrations.
Table 2pH, Turbidity, absorbance at UV 254 nm, total phosphorus (TP) and chlorophyll-aconcentrations in raw water used for jar tests.
| Reservoir | pH | Turbidity (NTU) | UV254 | TP (µg L-1) | Chl-a (µg L-1) |
|---|---|---|---|---|---|
| Cruzeta | 7.95 | 11.8 | 0.263 | 127.00 | 18.82 |
| Timbaúba | 6.85 | 21.4 | 0.327 | 89.50 | 27.30 |
| Dourados | 7.35 | 20.8 | 0.402 | 153.67 | 39.93 |
| Boqueirão | 8.43 | 24.2 | 0.264 | 62.00 | 46.10 |
| Passagem das Traíras | 8.46 | 35.0 | 0.509 | 163.75 | 89.79 |
| Gargalheiras | 8.66 | 15.5 | 0.401 | 189.50 | 90.83 |
3.2. PAC performance
The pH decreased as PAC dose increased with the coagulant application but final pH was always above 6.5 (data not shown). In general, the removal efficiency increased sharphly from dose 0 to 4 mg Al.L-1, achieving higher values between the dose 4 to 6 mg Al.L-1for all variables (Top Quality Vehicle GPS Tracker with Fuel Cap Sensor M508). Then, two situations were observed: the increasing in the dose did not cause an increasing in the efficiency for total phosphorus, chlorophyll-aand turbidity removal; or the efficiency increased continuously with the increasing of the Al dose for UV254High Carbon Steel Wire Lead Patenting Phosphate Production Line%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (430 Black Mirror Decorative Stainless Steel Sheet in Foshan). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Customized Easy Installation Modern Luxury Container Housed).
Figure 1Removal efficiency (%) for total phosphorus (TP), turbidity, humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with different concentrations of aluminium (0, 2, 4, 6, 8 and 10 mg Al L-1) and 30 minutes of sedimentation.
For most reservoirs, the minimal dose required to reduce in at least 50% the concentrations of the variables was 4 mg Al.L-1(Square Shape Glass Perfume Bottle Refillable Glass Perfume Bottle Atomizer Mist Bottle). This dose resulted in turbidity values ≤ 10 NTU, total phosphorus concentration ≤ 50 µg.L-1and chlorophyll-aconcentration ≤ 15 µg.L-1for Cruzeta, Timabúba e Dourados reservoirs. Boqueirão reservoir water achieved a turbidity of 10.3 NTU and had total phophorus concentration reduced to values below 50 µg L-1but clorophyll-aconcentration remained above 15 µg.L-1. The total phosphorus, turbidity and UV254removal efficiency for dose of 4 mg Al.L-1was significantly negatively correlated with the initial chlorophyll-aconcentration and pH (Atex Approved Level Measuring Instrument Level Sensor). The highest total phosphorus and turbidity removal were observed for chlorophyll-aconcentration range of 18.8-39.9 µg.L-1and pH range of 6.8-7.9. The highest UV254removal was observed for the same pH range but for even lower chlorophyll-aconcentration (18.8-27.3 µg.L-1).
Figure 2Removal efficiency (%) for total phosphorus (TP), turbidity (TURB), humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with the dose of 4 mg Al L-1and 30 minutes of sedimentation.
Figure 3Correlations between chlorophyll-aconcentration and pH with total phosphorus (TP), turbidity and UV254removal efficiency (%) based on the dose of 4 mg Al L-1.
4. Discussion
In general,Furniture Laminate Sheet/HPL Panel/Building Material, but its efficiency was affected by chlorophyll-aand humic substances concentration. We suggested that 4 mg Al.L-1is the best dose (better cost-benefit) to be applied in most of reservoirs tested. This dose changed the trophic state of water from eutrophic to oligo-mesotrophic conditions in Cruzeta, Timabúba e Dourados reservoirs and had intermediary effects on Boqueirão water in laboratory tests. The efficiency in total phosphorus removal is reported for in-lake PAC application (Wholesale Foldable Desk Silicon Mobile Phone Stand;10 Axis 3D CNC Heavy-Duty Metal Wire Bending Forming Machine;Bright Solar Power Outdoor LED Light Motion Activated Light for Garden Patio Path Pool;Concertina Flat Razor Barbed Wire Cbt-65 Carton Box). However,Woodworking Machine One Head Economic Model CNC Router.
The evaluation of PAC performance was investigated in terms of removal efficiency of variables after settling time of thirty minutes. Low performances indicates problems in sedimentation which can caused by poor coagulation or flocculation. High chlorophyll-aconcentration,Promotional Gift Fabric Textile Polyester Elastic Round Bracelets for Event.Customized EPDM NBR Rubber Bellows Expansion Joint, turbidity and UV254removal efficiency are correlated with higher values in initial pH and chlorophyll-aconcentrations. Initial pH has been reported to affect coagulation performance of PAC ( Table Gas Stove). In the maximal PAC performance pH was found to be around the neutral (API-5CT Standard Seamless Steel Pup Joint /Oilfield Services;Custom Lf 125kHz/Hf 13.56MHz Pet/PVC RFID Contactless Smart Card with Cheap Price). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Supporting DDR4 RAM Intel Core I5 Mini PC Computer) which determines the coagulation performance (Taper Roller Bearing). The dose of 4 mg Al.L-1resulted in pH >8.0 in Gargalheiras and Passagem das Traíras water thereby making the coagulation difficult. It has been suggested that high alkaline waters requires a higher PAC dose to achieve pH values favorable to coagulation (Vodafast A2 Stainless Steel Channel Nuts with Long Spring).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.dual Row 15pin D-SUB Mechined PCB Mounting Power Connector.
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