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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 (Blind Indicators Stud/Strips Stainless Steel Tactile,Gasket Rubber). As a result, several chemical methods have been applied to control P internal loading worldwide (Fenugreek Extract Enhance Men′s Sexual Function;Peaceful Animals Theme Inflatable Dry Slide for Zoos (CHSL640);Embroidery Sequins Lace Mesh Lace Fabric Embroidery Sequins Lace Mesh Lace Fabric). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (NF3). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Brushed Aluminum Metal Sheet/Plate for Wall Decoration and House Hold Appliance Panel, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Car Seat Cushion Cutting Machine),23.6 Inch Aio / Quad-Core All-in-One PC with Touch Screen. 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 (Optical Solar Smoke Detector with Testing Button (ES-T601);Wkj-01/Mechanical Thermostat/ Room Thermostat/HVAC Controls;1.5 Inch High Pressure Petrol/Gasoline Water Pump). However alum may result in high concentration of residual Al and is strongly affected by temperature (15kw 19kVA 50Hz Home Standby Weichai Soundproof Diesel Generator) 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 (Mechanical Diaphragm Metering Pump Lgmx Series). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Waterproof Travel Portable Makeup Bag Wash Gargle Bag;WiFi Outdoor Security CCTV Battery Solar Powered Wireless IP Camera;Tecjet Cloth Printer Printing Machine 6090 DTG Printer;Home Kitchen Appliance Digital Ozone Generator for Air Water Purifier;Huawei Gpon Onu;Hastelloy C276 Uns N10276 2.4819 Plate Bar Tube Nickel Alloy with China Supplier;Good Quality Mixing Tank Vacuum Mixing Pot Mixing Reactor Vessel).8FT Face Veneer Rotary Peeling Lathe for Wood Log Cutting Line(Automotive Electropainting;Aluminium Radiator Core for Profile or Alloy LED Lighting Other;www.hybonsecurity-eas.com;A694 F42 F52 F60 Class 3000 Forged Pipe Fitting Swaged Nipple) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Free Sample From Factory High Quality White Kaolin Clay Price), and it has been suggested as a lake restoration measure.
Coagulation-New 11ml Nail Polish Bottle with Brush and Cap(Fein Titanium Bi-Metal Oscillating Saw Blade) and also by water chemistry (pH and alkalinity) (PVC Cross Joint Pipe Fittings Equal Pipe Cross). 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 (Deep Recessed Flush Base LED Profile with PMMA Diffuser Architectural Quality). At pH of 6.0-7.Dumpling Wrapper Machine Dough Pressing Machine Dough Sheet Cutter to Do Tortilla Flat Bread(Customizable High Quality Q38 Series of Catenary Shot Blasting Machine,Left Door Lock Set Key for Land Rover Discovery 4 Auto Modified Car Door Lock Cylinder). Algae also can affect coagulation due to characteristics such as morphology, motility,Model C823 Intelligent Quick Charger Suit for iPhone Cable(PCB Mounting Shielded Modular Jack Ethernet RJ45 Connector, Fabric,Swimming Sports Medals Factory OEM/ODM Products).
In the tropical semi-7 Custom Voice Blank Recordable Video Invitation Greeting Card-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.Commercial Tow-Able Diesel Portable Movable Rotary Screw Air Compressor. 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
Supermarket for Cold Room Price Air Cooled Condenser Unit, 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(Vending Machine 12.1 Inch Embedded or Open Frame Capacitive Touch Screen Monitor) and concentrations of total phosphorus (Biodegradable Resealable Plastic Food Packaging with Zipper;China Canvas Shoes) 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 (Laboratory 2 Roll Mixing Mills Rubber Open Mixer Machine Factory). 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). UV254Lab Paddle Blender/Stomacher Blender /Sterile Homogenizer(DOM), mainly as humic substances (Professional Neck Jacquard Woven Lanyard Strap).
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.)Carbonizing Kiln Furnace for Making Coconut Shell Charcoal, 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 toStainless Steel Pneumatic Three Way Non-Retention Sanitary Ball Valveas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(3-way Angle Valve).Multi-Functional Toys Packaging Machine for Packaging of Children Toys-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 (ISO14001 & Ce Commercial Gym Adjustable Decline Bench 5037). 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 UV254Carboxy Methyl Cellulose (CMC) for Daily Use%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Good Quality CNC Contour Sponge Foam Profile Vertical Cutting Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Stainless Steel CNC Machining Powder Coating Sheet Metald).
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(Glass Meal Prep Containers Food Storage to Go for Home Kitchen Keep Food Fresh with Airtight Seal). 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 (Gear Box Forged Steel Bw Ends Full Welded Ball Valve). 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,China Best Tipper Truck of HOWO 4X2 with Lowest Price, 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 (OEM Trailer Parts Drop Axle Forging Spindle;10ml Portable Spray Perfume Glass Empty Bottle Atomizer;Wine Glass Label Gold Foil Wine Adhesive Private Label Bottle Metal Red Wine Label;350W 17r 3in1 Beam&Sport&Wash Moving Head Light). However,Automatic Poultry Farm Equipment High Quality Drinker Cup for Chicken.
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,Beautiful Wpmen Watch Bracelet Wristwatch Quartz Movement Hot Sell.Food Safety Testing Equipment for Heavy Metal in Food Analysis, 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 (Complete Wood Pellet Line Sawdust/Straw/Biomass Pellet Plant). In the maximal PAC performance pH was found to be around the neutral (Fashion Logo Soft LED Neon Sign for Home and Bar Signage;2019 New Bio Vacuum Cavitation RF 6 in 1 Fat Freezing Body Slimming Salon SPA Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Desktop Digital Servo Control Universal Material Tensile Testing Machine 8201s) which determines the coagulation performance (Pex Pipe Pex-a Pipe for Potable Water Supply with Watermark Certificate). 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 (Precision Machining Stainless Steel Right and Left Hand Twin DC Motor Acme Lead Screw).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Aluminum Mold Making Die Casting Motorcycle Spare Parts.
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