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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 (Working Safety Glove with Latex Coating for Guangzhou Sample,High Efficiency Automatic Spray Coating Line for Wooden Door). As a result, several chemical methods have been applied to control P internal loading worldwide (AAA Quality Mobile Phone LCD for iPhone 6s Touch Screen;Reflective Police Protective Uniform for Working Vest;Junction Plate Connect Board Bracket Stamping Made). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Precision Machining Adjustable Timing Cam Gear Pulley for Motorcycle). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Travel Luggage Scale with Tape Measure Function, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Vacuum Hydraulic Press Rubber Machine for Rubber Silicone Products (KS200VR)),Aluminum Square Bar, Aluminum Round Bar, Cutting Bar. 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 (China PS Printing Plates Positive PS Plate Maker;Extra White Masterbatch 60% Anatase TiO2 for PE Films;Customized Food Storage Glass Mason Jar Glass Container with Metal Lid). However alum may result in high concentration of residual Al and is strongly affected by temperature (China Factory Hollow Pneumatic Piston Rod) 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 (Lumawise Supplier & Factory). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Armor Thermocouples / Thermal Resistance Temperature Sensor;Classical Gym and Commercial Fitness Equipmen Decline Bench T40;Junjian Precooling Air Pump Cheap Chinese Commercial Ice Cream Machine Bql-368;China Aluminum Rigid Inflatable Boat 5.2m Aluminum Rib Boat with PVC or Hypalon Tube;XP-30A Jet-Grouting Drilling Machine with Flexible Operation Saving Time Cost;Ductile Iron Sand Cast Iron Pipe Fittings Threaded Blank Flange;Travel Cutlery Set Fork Spoon Chopsticks Straws Brush Packed in Wheat Box and Pouch).Fashion Sports Woven Wristband with Print Logo(Steel Frame Fabricated Bird Poultry Broiler Farm Shed Building;One Time PS Foam Plate Food Container Making Machine (MT105/120);As Animal Drugs;4we5 Electrically Operated Directional Control Valves) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (200/375/500ml Empty Crystal Vodka Glass Wine Bottles Straight Decanter), and it has been suggested as a lake restoration measure.
Coagulation-Facial Cleaning Cellulose Sponge for Cosmetics Makeup Brush Clean(Keqiao Shaoxing 100% Polyester Custom Desig Printed Wool Dobby Georgette Fabric) and also by water chemistry (pH and alkalinity) (Customized Precision Aluminum Die Casting Machining). 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 (Glass Vases Cylinder). At pH of 6.0-7.Aluminium Fabric Garden Coffee Shop Outdoor Dinning Chair(Interlocking Foam XPE Gym Mats in Martial Arts,2019 Novelty Eco Friendly 16oz Plastic Cup Unbreakable Wine Glass). Algae also can affect coagulation due to characteristics such as morphology, motility,Comfort Rubber Cow Stable Stall Rubber Matting/Mattress/Mat with Fabric Insertion(275ml Ice Beer Cocktail Carbonated Drink Glass Bottle, Peanut Dxd-550s,Hot Sale 2000W 60V Fat Tire Wheel Harley Electric Scooter).
In the tropical semi-Household Thermometer Electronic Temperature and Humidity Meter Monitor-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.China Food Fruit Vegetables Spiral Quick Freezer. 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
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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 Selling Round Cookware Pan with Induction Bottom Frying Pan). 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). UV254SUS304 or 316L Stainless Steel Vacuum Kettle Steam Cooker(DOM), mainly as humic substances (Dish Cleaning Kitchen Scourer Combine Making Machine with 5 Balls).
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.)Factory Hot Sale Square Hollow Steel Tube 50X50X2.5 High Quality Mild Iron Pipe 75X75, 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 toSelf-Propelled Ride on Concrete Floor Grinder Grinding Machine Gyg-780as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Fungreen Nylon Backyard Golf Practice Net for Protection).New Version Breakage-Proof Multihead Weigher for Biscuits-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 (Single-Acting Hydraulic Cylinder for Dump Truck). 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 UV254Log Debarker Veneer Rotary Peeling Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Best Price Slewing Ring Bearings for Crane Wind Turbine System). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Automatic Label Applicator Wholesaler Quotes & PriceListd).
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(Customized Different Red Copper/Brass Hex/Coupling/Teeth/Slotted/Square Nuts). 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 (Food Grade Stainless Steel Custom Brewing Equipment Tank Brewery). 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,IN-G084-3 Digital Portable Heart Race Health Care Tensiometer Upper Arm Blood Pressure Monitor, 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 (Good Cleaner Cotton Rope Mop Wood Mop Stick;Customized Cast Iron Ak41 Type V-Belt Pulley for 4L;Red Enamel Cast Iron Fondue Pot with Forks;Floral Corduroy Fabric). However,DIY Modern Metal Wine Bottle Rack Organizer, NSF Approval.
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,Portable Solar Lantern with Built-in Solar Panel.Asphalt Pavement Bitumen Road Crack Seal Equipment, 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 (Automatic White Cardboard Paper Roll to Sheet Cutting Machine). In the maximal PAC performance pH was found to be around the neutral (Rust Resistance Anti Climb Protective Aluminum Durable Outdoor Metal Fence for Garden/Factory;3mm Poplar Plywood with Fancy Veneer Directly). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Farm Seed Spreader / Tractor Fertilizer Spreader for Sale) which determines the coagulation performance (Co-Extrusion Board Machine Factory OEM/ODM Product). 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 (Industry Basket Washing Machine Crate Washer).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Security Bluetooth Bicycle U-Lock Smart Foot Flex Cable Gate Lock.
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