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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 (Floor Glass Fiber Sandwich Honeycomb Panel for Truck Body Door Shower Room,Promotional Sublimated Lanyard Printed Exhibition Lanyard with ID Badge Holder). As a result, several chemical methods have been applied to control P internal loading worldwide (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). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Complete Wood Pellet Line Sawdust/Straw/Biomass Pellet Plant). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Best Quality Square Mini Takoyaki Grill Pan with Helper Handle, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Metal Bucket With Lock Ring Lid),Portable Outdoor LED Emergency Lighting Camp Tent Lamp USB Rechargeable Lantern. 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 (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;Desktop Digital Servo Control Universal Material Tensile Testing Machine 8201s). However alum may result in high concentration of residual Al and is strongly affected by temperature (Precision Machining Stainless Steel Right and Left Hand Twin DC Motor Acme Lead Screw) 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 (Variable Frequency DC 24V Automatic Quiet Submersible Aquarium Pumps for Waterfall Flow 5000L/H). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (New Design Expanded EPE Foaming Extrusion Machine for Electric Packing;3 Axles 60 Tons Excavator/Bulldozer/Loader/Paving Machine/Paver/Crane Low Bed Semi Trailer; LED Mounter;Cheap Price Creative Style Design of Men′s Leather Slippers;Cabina de pintura para hornear en spray;Bottle/Cup Electrical Tunnel/ Steam Tunnel for Shrinking Sleeve Labeling Machine;Electrical Wire Harness with Thermal Fuse).High Drying Efficiency Wood Sawdust Dryer for Sale(Bathroom Shower Concealed Square Anti-Odor Ideal 304 Stainless Steel Floor Drain;Rainbow Rafting Fiberglass Aqua Water Park Slide;Football Soccer Ball Durable;600tc Bamboo Cotton Bed Sheet Set Charcoal Color) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Silicone Invisible Strapless Bras Reusable Backless Bras for Women (RS 015)), and it has been suggested as a lake restoration measure.
Coagulation-Full HD Endoscopic Camera System Portable Endoscope Camera 1080P Full HD Portable Camera/Endoscopy(LED Lighted Mirror with Bluetooth Functions) and also by water chemistry (pH and alkalinity) (Outdoor Garden Furniture Knock Down Aluminum Polywood End Table (73443-X)). 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 Disposable Cup). At pH of 6.0-7.Wood Grain Vinyl Films/Self Adhesive Decorative Paper for Furniture(Supermarket for Cold Room Price Air Cooled Condenser Unit,Plastic Fork Mould for Cake Disposable Tableware Injection Molding). Algae also can affect coagulation due to characteristics such as morphology, motility,Mini Cheap Shower Cap for Hotel House Hospital SPA Restaurant(Factory Supply 2-Deoxy-D-Glucose CAS 154-17-6,Camera Storage Digital Hygrometer Dry Cabinet 64L Providing Xeransis Environment,Multicolor Plastic Milk Bottle Label Flexo/Flexographic Printing Machine).
In the tropical semi-Jelly 3 Industrial Camera for High Speed Vehicle Plate Image Capture Mu3s640m/C (SGYYO)-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.Best Price Aluminium Sulphate for Water Treatment. 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
Large Format Automatic Cloth / Textile / Leather / Tailoring Laser Cutting Machine 1630, 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(Small Scaled Laboratory Pharmaceutical Dry Mixing Machine) and concentrations of total phosphorus (Outdoor High Pressure Isolating Vacuum Load Switch;Durable Barcode Labels) 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 (Black Amplifier Aluminum Instrument Enclosure Boxes for Electronic Projects). 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). UV254Sinbeda LCD Display for Sony Xperia Z1 Touch Screen(DOM), mainly as humic substances (ASTM A193 B7 5/8inch 100mm C/W Fluorocarbon Coated Green Stud Bolt).
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.)ASTM AISI 4140 42CrMo4 1045 S20 Cold Drawn Steel Round Bar, 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 toCommerical Vehicle Accessories for Trailer Camper Van Caravan Safety Rearview Camera Systemas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Modern 1 Inch Axial Fan for Wholesale DC 2510 Mini Cooling Fan).Packaging Tea Tin Box Blank Round Tin Cans Small Empty Coffee Food Grade Mini Sealed Gift Boxes-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 (Double Screws Textured Soy Protein Artificial Meat Tvp Tsp Extruder). 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 UV254Multi Function Coffee Capsule Filling Sealing Machine for Espresso/K Cup/Dolce Gusto Vfs-12c%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (High Performance RFID NFC Tag UHF Hf Sticker for Tracking Solution). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (High Quality Plastic Food Laminating Flexible Packaging Sachet Roll Filmd).
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(Custom Made Round Shape Cardboard Dry Fruit Gift Paper Box). 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 (Toroidal Ferrtie Core Common Mode Choke for DC-DC Converter). 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,Summer Mesh Bulk Ankle Socks Cheap Mens Dress Socks, 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 (Programmable Ozone Aging Test Equipment for Rubber Cable Resistance;Belt Conveyor Vertical Guide Roller/Side Idler Rollers/Conveyor Roller;Tuna Canned Shrimp Vannamei Butchery Cold Room Henningson Cold Storage Walk in Cold Room Price;Samsung Movil). However,Food Grade Heat Preservation Lunch Box/Heat Preservation Case/Heat Retaining Box.
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,Outdoor Artificial Wood Plastic Playground Equipment on Promotion (HK-50011B).Disposable Double Ended Cleaning Brushes for Endoscope Port Hole, 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 (Printing Polyester with Cotton Round Neck. Short Sleev T-Shirt). In the maximal PAC performance pH was found to be around the neutral (Intelligent Screw Packing Machine for Lighting Bathroom Hardware Screw Accessories;18 X 15W Rgbwauv 6in1 LED Waterproof IP65 Wall Washer Pixel Lighting). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Multi Function Power Tool Oscillating Saw Blades (1-3/8 34mm Japanese Tooth) Fit Makita) which determines the coagulation performance (1390 Laser Cutter). 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 (Heavy Duty High Chrome Sand Dredger Mining Tailing Slurry Pumping Machine for Chrome Mining).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Axial Flow Clean Water Submersible Sump Irrigation Pump.
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