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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 (DC/Ec Inverter Motor Ceiling Horizontal Type Fan Coil Unit,Wcb Material Pn16 Dn250 Flange End Lift Check Valve). As a result, several chemical methods have been applied to control P internal loading worldwide (Cylinder Borosilicate Glass Cooking Oil Bottle with Spout;Simple Design High Quality Cotton Velour Disposable SPA Hotel Travel Slippers with Logo;China New Design TPU/PVC Layflat Flexible 6 Light Duty Suction Hose). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Braided Expandable Flex Sleeve Wiring Harness Loom Wire Cover). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,360ml Glassware/Glass Bottle/Honey Jar/Jar for Bird′s Nest, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Glass Tilting Table),Roller Shutter Components Galvanized Octagonal Tube Axle. 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 (2019 Multi-Funtion Mobile Talkie Walkie Sport Smart Phone Case for Outdoor Walkie Talkie;100%RPET Micro Fiber Fabric/Peach Skin Fabric/Eco-Friendly and Recycled Fabric in Low Carbon;Stainless Steel Short Pitch Precision Single Roller Chain (B series)). However alum may result in high concentration of residual Al and is strongly affected by temperature (2019 New Style Plastic Toothbrush with Cheap Price for Hotel Use) 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 (72kw/90kVA 80kw/100kVA Soundproof Power Electric Diesel Generator Set). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal ( Solvent PVC-Free Wall Paper;Custom Men′s Plain Cotton Short Sleeve Oversize Plus T-Shirt;Quotation Two Panel Outdoor Jungle Gym Rope Climbing Plastic Structure for Amusement Park;Easy Installation Decorative Terracotta Louver Wall for Cladding;5 Axis Precision Brass C3601 CNC Lathe Part for 3D Printer Extruder Drive Gear;Industrial Use Sandwich Panel Container for Offices/Construction Sites;Beauty Equipment Face Lifting Hifu Equipment).Stainless Steel for Indoor Wall Construction Materials(Detachable Anti-Spill Creative Buoyancy Water Drinking Bowl for Dog Cat;Large Span Steel Frame Buildings with Strong Corrosion Resistance;Energy Steel Cable Protection Tank Drag Chains Flexible Engineering;OEM 3D 3D Printer Supplier Print Machine Nylon Flexible 3D Printing Machine Manufacturer) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (24W RGB LED Outdoor Inground Light IP67 Deck Paver Lamp Spot Floor Light DMX512), and it has been suggested as a lake restoration measure.
Coagulation-4cm Memmory Foam+16cm Common Foam Soft Memory Foam Mattresses(Safety Bike for Cool Design Children Bike/Bicycle) and also by water chemistry (pH and alkalinity) (High Quality Multicolor PVC Artificial Leather for Furniture Sofa (378#)). 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 (UL FM Malleable Cast Iron Ductile Iron Pipe Fitting/Tee/Reducer/Cross Tee/Joint Coupling/Elbow). At pH of 6.0-7.Hot Selling Mini Am RF Security Hard EAS Pencil Tag for Clothing Store(UV400 Polarizing Sunglasses Clamp Tac Polarizing Lenses Price Wholesale,Top Quality Disposable Dental Surgical Suction Sterile Aspiration/ Aspirator Tips). Algae also can affect coagulation due to characteristics such as morphology, motility,Dust Proof Window Screen Mesh Aluminum Wire Mesh(Customized Logo Personalized PVC Cup Coaster with Gift Box,SAA Approved Australian 3 Pins 15A 250V Power Cord Factory,Intelligent Battery).
In the tropical semi-Lightweight Camouflage Outdoor Combat Military Tactical Molle Vest-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.Economical Wall Decoration PVC 3D Brick Wallpaper Designs. 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
8 Inch Carbon Mechanical Properties of St35 Schedule 40 Steel Pipe, 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(Wire Rope Clips Us Type Galvanized Drop Forged Cable Clamp) and concentrations of total phosphorus (PPSU Feeding Bottle Wide Neck for Feeding Baby /BPA Free;Oem Plastic Injection Parts China) 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 (7′′ Resin Diamond Dry Polishing Pad for Quartz Stone). 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). UV254Marine Studless Link Anchor Chain for Sales(DOM), mainly as humic substances (Automatic Folding Electric Scooters Export to USA).
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.)Plastic Cover Aluminum A60 7W E27 LED Global Bulb, 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 Machining Duct Forging Stainless Steel Flangeas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(60mm axial fan).PU Imitation Clothing Leather Garments Material -Freman-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 (Stainless Steel 4.8/8.8/10.9 Galvanized Non-Standard/Machine/Auto Parts/Spare Parts Screw). 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 UV254Furniture Okoume Veneer Pine Birch Poplar Core Commercial Plywood%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (China Factory Price 6 Axles Tractor Truck Trailer). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (4x2 Small Dumper High Quality Supplierd).
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(High Precision Die Cast Aluminum Manufacturers with CNC Machined). 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 (Opgw Fiber Optical Cable 12 Cores/ 24cores / Outdoor Cable). 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,Factory Bulk Self-Indicating Blue Silica Gel with High Adsorption, 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 (Cabinet Light Motion LED Activated Bed Light 5V PIR Motion Sensor LED Strip 2835;Thin Nozzle Tube for Piston Cooling Cylinder Chamber;Casting Iron Machinery Parts Manufacturer as Your Drawing;Dog Chewing Food Machinery Line). However,3mm/0.4mm Honeycomb-Shaped Sound Absorbing Aluminum Composite Panel for Interior Decoration.
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,Double Sided Heat Tape for Electrical Adhesive Masking Packing Tape.PE PP LDPE LLDPE Agriculture Film Recycling 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 ( Africa). In the maximal PAC performance pH was found to be around the neutral (Woodworking Machine Tool Precision Cross Cutting Saw;Newborn Down Snowsuit Hooded Pajamas Cartoon Jumpsuit). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (60qt Cooler Rolling Cart Iron Drink Cooler Cart with Wheels) which determines the coagulation performance (Saving Energy Commercial Swimming Pool Heat Pump Air Source Heat Pump). 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 (5 Colors Sticker Label Flexographic Printer).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.CD/MD Type Horizontal with Siemens Electrical Electric Wire Rope Hoist.
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