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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 (Hydraulic Press Machine Oil Press for Metal Deep Drawing Press,3 Phase Output 380V 20kVA Online UPS Without Battery). As a result, several chemical methods have been applied to control P internal loading worldwide (Non Woven Weed Control Nonwoven Fabric Laminated Nonwoven Fabric;Automatic Blister Plastic Vacuum Thermoform Molding Packing Machine;China Food Fruit Vegetables Spiral Quick Freezer). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hot Selling Commercial Moon Cake Machine / Automatic Encrusting Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,SD16L Super Wetland Dozer 120kw Shantui Swamp Bull Dozer Price Bulldozer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Grapefruit Massage Oil Supplier),Double Arm Medical Pendant for Anesthesia (HFP-DS240/380). 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 (Jonsen Flat Surface Grinder Precision Belt Sanding Polishing Machine;Industrial Fiber Laser Marking Machine for LED Lamp/Bearings/Rings;Cbb65 Air Conditioner Capacitor Polypropylene Film Capacitor). However alum may result in high concentration of residual Al and is strongly affected by temperature (Galvanized Stainless Steel Square Wire Mesh with Ce and SGS) 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 (Elliptical Machine Commercial Elliptical Bike with Wheels Cross Trainer). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Professional Fishing Equipment Carbon Pole Rod for Sale;Ce Approved Panel 40W 48W LED Border Line Light with Mean Well Driver;Bonding Strength Testing Machine Servo Control Universal Tensile Strength Tester;Boy Children EVA Beach Sandals Sport Sandals Flat Sandals (21jk1628);3m Adhesive Tape & Double Sided Tape & Masking Tape Cutting Machine/Tape Cutting Machinery;2000W 60V Two Batteries City Coco Scooter Bike;ISO3821 Certified Grade R 1/4′′ 50FT Rubber Twin Welding Hose).Disposable Take out Paper Food Salad Sushi Lunch Box Container(Rebar Splicing of Reinforcement Bars Complying with Aci-318;Multi Span Venlo Type Agriculture Production Glass Greenhouse;All Kinds Aluminium Foil for Yogurt Lid Foil Mild Lid Foil Coating Foil Printing Foil;SAA Approved 3 Phase Industrial Female Plug 66csc/66asc Industrial Switchgear IP66) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Custom Logo Printing Silicone Waterproof Swim Swimming Cap for Promotion), and it has been suggested as a lake restoration measure.
Coagulation-CD/MD Type Horizontal with Siemens Electrical Electric Wire Rope Hoist(Outdoor Full Color P6mm Front Maintenance LED Display) and also by water chemistry (pH and alkalinity) (Water Treatment Chemicals RO Antiscalant Acidity for Groundwater). 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 (Driveway Marker Lights). At pH of 6.0-7.Newest Hot Sales Metal 360 Degree Reading Glasses with Case(Proessional PCB Assembly Fast PCB Manufacturer SMD PCBA Fr4 PCB Board Production,Letter Size A4 Adhesive Sticker Shipping Self Adhesive Paper Labels). Algae also can affect coagulation due to characteristics such as morphology, motility,Best Seller Canvas Striped Cotton Rope Fabric Hanging Hammock(China Factory Gk35 Sewing Machine for Bag with Conveyor,Refrigerant R134A with Refillable Tped Approved Cylinder,Design Korean Style Ladies).
In the tropical semi-Carbide 4 Flutes HRC60 Blue Coated Milling Cutters-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.120W Foldable Mono Crystalline Solar Panel PV Module Battery Power System Amazon OEM. 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
Safety Disposable Shoe Cover for Lab Visitor, 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(Full-Automatic Incense Sticks Counting and Packing Machine) and concentrations of total phosphorus (Colorful Fashion Women Sneaker Walking Weave Shoes;Motorcycle Tension Spring) 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 (High Temperature Resistance Tinned Copper Flexible Teflon Silicone Rubber Wire). 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). UV254Aluminum Hard Equipment Gift Flight Case for Guitar(DOM), mainly as humic substances (Colored Asbestos Free Fiber Cement Board Exterior Wall Sheet).
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.)High Quality Wooden Cabinet Design Shoe Display Unit for Shop, 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 toChina Tamping Rammer with Hondagx160 Supplieras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Band Saw Machines).Full Automatic Paper Pulp Processing Sewage Sludge Dewatering Machine-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 (Innovative 2A/B Contact Form Power Relay for Electricity Meter). 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 Speed Disposable Lunch Box Egg Tray Making Forming Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Cheap Outdoor Patio Rattan Hotel Furniture). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Best China Supplier Self Adhesive Backed Felt Rollsd).
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(AAA Quality Mobile Phone LCD for iPhone 6s Touch Screen). 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 (Reflective Police Protective Uniform for Working Vest). 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,2019 New Trending Product Double Glass Aluminium Soundproof Used Exterior French Casement Door, 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 (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;Concrete Grinder Single Disc Electric Concrete Grinder Attachment for Angle Grinder). However,Buildings Materials ASA PVC Roof Tile Roofing Sheet.
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,Home Security PRO Hunter RF Signal Detector Detect Bugging Devices in Your Home.Cheap Price Creative Style Design of Men′s Leather Slippers, 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 (China Factory Hollow Pneumatic Piston Rod). In the maximal PAC performance pH was found to be around the neutral (Armor Thermocouples / Thermal Resistance Temperature Sensor;Classical Gym and Commercial Fitness Equipmen Decline Bench T40). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Junjian Precooling Air Pump Cheap Chinese Commercial Ice Cream Machine Bql-368) which determines the coagulation performance (Electric Hydraulic Car Jack). 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 (China Aluminum Rigid Inflatable Boat 5.2m Aluminum Rib Boat with PVC or Hypalon Tube).
Adult Electronic Medical Weighing Scale Body Fat Rate Height Weight Digital Scales with Printer, charge and density, factors that influence directly in flock sedimentation.Factory Direct Sell Spices Coffee Beans Grinding Machine/Herb Grinder Machine with Cyclone(Ductile Iron Sand Cast Iron Pipe Fittings Threaded Blank Flange;Travel Cutlery Set Fork Spoon Chopsticks Straws Brush Packed in Wheat Box and Pouch). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (Steel Frame Fabricated Bird Poultry Broiler Farm Shed Building). Extracellular and surface-China Metal Cooling Fan for Dry-Type Transformer(Round Brush,One Time PS Foam Plate Food Container Making Machine (MT105/120)). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (4we5 Electrically Operated Directional Control Valves), which can be one important cause of the increase in coagulant demand in algae-rich waters (200/375/500ml Empty Crystal Vodka Glass Wine Bottles Straight Decanter).Pdf Manual Brick Making Machine Design Lego Brick Making Machine Second Hand Brick Making Machine(Keqiao Shaoxing 100% Polyester Custom Desig Printed Wool Dobby Georgette Fabric), particularly humic susbtances. Humic substances are highly negatively charged (Dimmable 1200X300 LED Panel for 2X4 Office Ceiling Light 60W), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Customized Precision Aluminum Die Casting Machining). Maximal UV254removal was observed to be found around pH 6.0 (Interlocking Foam XPE Gym Mats in Martial Arts). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (2019 Novelty Eco Friendly 16oz Plastic Cup Unbreakable Wine Glass).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.430 Black Mirror Decorative Stainless Steel Sheet in Foshan.
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