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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 (High Efficiency Refrigeration Equipment Water Cooled Industrial Chiller,T/R/Tel/Sp Fabric for Coat Suit and Pants Garment). As a result, several chemical methods have been applied to control P internal loading worldwide (6000 Series Alloy Customized Black Anodized Black Aluminium Extruded Enclosure;HDPE 1mm 2mm Plastic Strips /Tapes Manufacture for Decorate Christmas;Touch Screen Display Module Control Panel for Instrument). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Environmental Shot Peening Machine with Less Dust Emission). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,CNC Contour Foam Cutter for Polyurethane Rigid Blocks/Sofa Furniture Sponge Cutting Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (25mm Tk ASTM A572 Series Hot-Rolled Low-Carbon Steel Plates),30W PA System Surround Sound in Ceiling Mount Speaker Waterproof Speaker. 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 (Roll up High Quality Luxury Comfort Spring Mattress;High Quality and Precision Chroming Zinc Plating CNC Machined Hardware for Medical Instrument;A4 A5 Discoloration PU Leather Planner Agenda Diary Notebooks with Stamping Logo). However alum may result in high concentration of residual Al and is strongly affected by temperature (PS126 Electric Automatic Surface Vortex Peripheral Motor Water Pump) 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 (Pur Telephone Cable). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Agricultural Utility Model Rod-Spray Machine Hung Onto Roller Tractor;Poly Aluminium Chloride (PAC) for Drinking Water Treatment;18 mm OSB (Oriented Strand Board) for Roof Decking;Ce Approved Acrylic Mini LED Letters Sign for Outdoor;Promotion Backpack Factory OEM/ODM Products;Mobile Phone LCD Display for iPhone Xr Digi-Top OEM 1: 1 OLED Touch Screen LCD Display;Free Sample High Quality GSM External Antenna).Auto Parts 6W Flood LED Head Tail Car Work Light Lamps for Excavator(New Design Infrared Touchless Automatic Sensor Electric Water Faucet;Deutz-Fahr Haester Agriculture Combine Harvester 4yzp-4L for Wheat/Rice/Soybean/Corn/Graize;Size;Video Tripods Monopod Self Aluminum Camera Tripod) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Plastic Logistics Daily Use Plastic Injection Crate Mould), and it has been suggested as a lake restoration measure.
Coagulation-8mm PVC Coated Galvanized Steel Wire Rope for Lifting(New Avaival Silver Hico Blank Magnetic Stripe Cards) and also by water chemistry (pH and alkalinity) (China Best Quality Goof Price Tpo Flat Roofing Waterproof Membrane). 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 (China 9 Trialkylamine - Trioctyl /Decylamine). At pH of 6.0-7.SAE 100 R1 R2 1sn 2sn Hydraulic Hose Assembly Fittings(Customized Embossing Logo Soft Flexible PVC Bar Mat,20 Cavity Pet Preform Mould with Competitive Price). Algae also can affect coagulation due to characteristics such as morphology, motility,DIN Rail Mechanical Thermostat, Temperature Controller Thermostat 110V for Cabinet Use(Women′s Knitted Acrylic Sweater Fashion Dress,118 120 TV Tel Socket,Touch Screen Lcd Tv).
In the tropical semi-Classic European Style Universal Wrench& General Reciprocal& Utility Wrench-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.Brushed Aluminum Metal Sheet/Plate for Wall Decoration and House Hold Appliance Panel. 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
23.6 Inch Aio / Quad-Core All-in-One PC with Touch Screen, 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(Key Chain Metal Key Rings Acrylic Key Bag Holder) and concentrations of total phosphorus (Silicon Carbide Black/Green Use to Produce Angle Grinder Polishing Disc;Brass Fire Fighting Gate Valve) 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 (LCL Consolidation Shipping Freight From Guangzhou to Dayton). 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). UV2548FT Face Veneer Rotary Peeling Lathe for Wood Log Cutting Line(DOM), mainly as humic substances (Yako Brass Waterproof Balcony Toilet Bathroom Floor Drain).
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.)New 11ml Nail Polish Bottle with Brush and Cap, 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 toAutomatic Column and Boom Welding Manipulator Dlhas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Australian AC Power Cord with SAA Certfication Plug and C13 Connector).Dumpling Wrapper Machine Dough Pressing Machine Dough Sheet Cutter to Do Tortilla Flat Bread-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 (off-Grid Residential Small Wind Turbine 1kw 12V Generator Kit). 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 UV254Model C823 Intelligent Quick Charger Suit for iPhone Cable%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (XBD Series Single-Stage Single-Suction Fire-Fighting Pump). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Mobile Nfc Sticker High Quality Supplierd).
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(Clothes PU Reflective Heat Transfer Vinyl CO2 Laser Cutting Machine). 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 (Recessed Colorful Solar Interaction LED Underground Lighting). 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,7 Custom Voice Blank Recordable Video Invitation Greeting Card, 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 (Hot Salse Factory Supply Galvanized Steel Angle for Gypsum Board;295L Commercial Horizontal Curved Glass Door Freezer;YAMAHA Ybr125 Carburetor Motorcycle Parts-Oumurs 11950603101;Sandwich Roofing). However,Commercial Tow-Able Diesel Portable Movable Rotary Screw Air Compressor.
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,Supermarket for Cold Room Price Air Cooled Condenser Unit.Lab Paddle Blender/Stomacher Blender /Sterile Homogenizer, 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 (Custom Souriau Connector Header with Cable). In the maximal PAC performance pH was found to be around the neutral (High Speed Disposable Lunch Box Egg Tray Making Forming Machine;2018 Hot Sale Freestanding PVC or MDF Material Australia-Style High Glossy Paint Bathroom Cabinet). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (90W 1750rpm Small AC Single Phase Electric Motor with Capacitor) which determines the coagulation performance (240mm Grinding Wheel). 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 ( USA).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Automatic Poultry Farm Equipment High Quality Drinker Cup for Chicken.
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