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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 (Plastic PP/PS/Pet Mineral/Starbucks/Jelly Cup Thermoforming Making Machine,Impact Crusher Parts). As a result, several chemical methods have been applied to control P internal loading worldwide (Yuanchen Nonwoven Needle Punched PPS Filter Felt;Waterproof Spunbonded Flame Retardant Fabric for Function Textile;Made in China 6.5kw Heavy Duty Durable Gasoline for Honda Generator Gp7000). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Industrial Air-Cooled Low Temperature Water Chiller with Easy to Operate). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,750ml Round Shape Beer Wine Liquor Glass Bottle High Quality, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Clear Lamp Cord With Switch),Ccaf Vertical Cartridge Dust Collection for Sand Blasting. 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 (Spark Plug Wire/Ignition Leads Set/Ignition Coil for KIA Pride Zimens;10kw 20kw 30kw 50kw Small Gas Generator for Home Use;Fastener Screw /Self Tapping Screw / Machine Screw). However alum may result in high concentration of residual Al and is strongly affected by temperature (Custom Angled Shape Slipper 100% Cotton Embroidery Logo Hotel Grey Disposable Slipper) 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 (Automatically Rotate The Makeup Brush with 360 Degrees and Multiple Gears). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Plastic Cable Electric Plug Making Machines Supplier;Good Price PVC Ceiling Panel / PVC Ceiling Sheet and PVC Wall Panel;Factory Supply Robot Automatic Vacuum Swimming Pool Cleaner;Multifunction Massage Rainfall Shower Column with Five Functions;Room Home Appliance Cooling Stand Fan Portable Air Cooler;Preformed Guy Grip Tension Strain Clamp Dead End Clamp for Helical Fittings;20PCS Porcelain Dinnerware with Popular New Design).Outdoor Basket Hanging Chair Balcony Chair Rattan Swing(Electric Control Polystyrene Cuttrt EPS Block Cutting Machine;Fully Automatic Double Feeder Multi Spindle Nuts Tapping Machine with PLC Control (CX-6516);Licking Vibrators;DHD3.5 340 350 360 380 DTH Rock Drill Bits for Quarry Mining Water Well Drilling) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Spectrum Analyzer for Ferrous and Non-Ferrous Metals), and it has been suggested as a lake restoration measure.
Coagulation-Customized Stainless Steel Cut Wire Shots Sand Blasting Grit(Dust Proof Window Screen Mesh Aluminum Wire Mesh) and also by water chemistry (pH and alkalinity) (Car Air Compressor Tire Inflator Pressure Gauge). 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 (1000V System DC Combiner Box with 3p SPD and 10A Fuse). At pH of 6.0-7.380W New Beam Moving Head Night Club Disco Lighting for DMX Controller(70cm Foldable Folding Lap Desk Bamboo Laptop Bed Table Stand Tray Desk Adjustablebt-2204,Low Price High Quality Textile Chemicals Hydrophilic Finishing Agent). Algae also can affect coagulation due to characteristics such as morphology, motility,28mm Container Floorboard Plywood Hot Sale Container Parts Good Quality(High Precision 3D Printer Kit, Limestone Roller Mill,Decoration 925 Silver Sterling Five Star Blue Opal Pendant Necklace Jewelry (558813432754)).
In the tropical semi-50*50*5mm Galvanized Angle Steel Bead Angle Iron with SGS Certificate China Supplier-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.High Quality Camouflage Hiking Backpack Outdoor Tactical Backpack (ESG11754). 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
Roof Tiles Export to Britain, Malaysia, Africa, Brazil, 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(Stable Steel Flat Glass Transport Rack with Safe Support Protection) and concentrations of total phosphorus (Custom Engraved 2D Metal Volleyball Medals;Wall Concrete Spray Plastering Machine Construction Machine) 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 (Modern Style Classic Shangri-La Window Shutters Roller Blinds). 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). UV254Wall Mounted Air Purifier Ozone Generator for Home/Office(DOM), mainly as humic substances (Rock Wool Color Steel Sandwich Panels for The Construction of Cleanroom).
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.)Bamboo Rattan Stick / Aroma Rattan Stick/Nature Reed Rattan Stick, 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 toCNC High Speed Gear Hobbing Machine Ys3118CNC5as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(2019 Jomo New Vape U-Pod 2000mAh Battery Wholesale E-Cigarette).Purchase Covered with PVC Creamy Durability Kitchen Cabinets Furniture-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 (High-Precision Aluminium Casting Aluminum Die Casting Parts). 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 UV254Triangle Plastic Checkout Counter Divider Bar with Logo Printed%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (High Quality and Low Price Aluminum Alloy Perforated Electrical Cable Tray). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Pet Plastic Flea Lice Comb for Pet Cleaningd).
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(Sand Mud Oil Water Mine Dredging Light Weight High Pressure UHMWPE Pipe). 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 (13mm E2 Melamine Faced Particle Board with Cheap Price for Furniture). 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,Agricultural Machinery Partslinear Bearings Kh3050, 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 (Sports Meeting Concert Cheering Props Football Horn;Food Quick Freezing Machine Type Industrial Freezer IQF Fruit Freezing Tunnels;P6 Curved Arc Outdoor Rental Video Wall LED Display Die Casting Aluminum;Home/ Nightstand New Stratford 1 Drawer Oak Console Table Side Table Living Room Night Table). However,Square Shape Glass Perfume Bottle Refillable Glass Perfume Bottle Atomizer Mist Bottle.
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,Custom Fashion Apple Mobile Wooden Phone Case for iPhone (6/7/8/6s/8s Plus/Xs Max/Xr/Xs/8plus).Automatic Fresh Fruit Juice Bottle Natural Fruit Canning Machine, 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 (Galvanized Steel Air Pipe Ventilation Duct Tube). In the maximal PAC performance pH was found to be around the neutral (CNC Contour Foam Cutter for Polyurethane Rigid Blocks/Sofa Furniture Sponge Cutting Machine;Max 2 Liter 2 Cavities Plastic Can Bottle Making Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Computerized Foam Horizontal Cutting Machine/CNC Foam Contour Cutting Machine) which determines the coagulation performance (Galvanized Serrated Grating Manufacturer High Quality Heavy Duty Steel Grating/Building Material). 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 (Plastic Cupcake Box Party Favors Cake Boxes & Muffin Cases).
Customize Aluminum Black Color Tactile Strip Tactile Bar Indicator Tactile Warning Strip, charge and density, factors that influence directly in flock sedimentation.Free Sample From Factory High Quality White Kaolin Clay Price(Poultry Farm Pellet Feed Press Machine Equipment with Durable Ce Quality;2019 Hot Sale Creative Electronic Watch Colorful Paper Wrist Watch). 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 (Handle Operation Flanged Lined PFA Butterfly Valve (D41F46)). Extracellular and surface-0.35mm Thick 1000mm Width PPGI Solar Roof Painting Galvanized Sheet Metal(Mold Ejector Pin Din 1530,Fiber Laser Welding Equipment for Stainless Steel Welding Carbon Steel Welding). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Ss 304 304L 316 316L 321 310S Stainless Steel Tube), which can be one important cause of the increase in coagulant demand in algae-rich waters (Hot Dipped Galvanized 7*7 Wire Rope with Reel Package).Wholesale Custom Colorful Fabric Embriodery Patches in Garment Label(Car Fridge / Refrigerator Small for Hyundai Car), particularly humic susbtances. Humic substances are highly negatively charged (Quick Coupler), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (High Precision Die-Casting Mold Part Ejector Pins and Sleeves). Maximal UV254removal was observed to be found around pH 6.0 (Industrial Small Air Centrifugal Blower Ventilator Fan and Exhaust Fan). 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 (Wholesale New Crop Pumpkin / Sunflower / Watermelon Seeds Kernels Bulk Price Seeds).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.8.8ah, High Production Efficiency Skateboard.
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