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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 (Commercial Tow-Able Diesel Portable Movable Rotary Screw Air Compressor,Embroidered Dad Hat). As a result, several chemical methods have been applied to control P internal loading worldwide (4 Cencter Set Lavatory Plastic Faucet (smooth and easy opening);Cold Storage Warehouse Rack with Good Quality;Brc Welded Wire Mesh Fence/3D Curvy Welded Wire Mesh Fence). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (A4). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Best Polystyrene Sandwich Board Manufacturer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (hbzhongrunfelt),Outdoor WPC Wood Plastic Composite Fence Board with High Quality. 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 (High Efficiency Hook Type Shot Blasting Machine for Sale;Non-Toxic RTV Silicone Sealant of Full Automatic Machine;High Tensile Forged Chain with Conveyor for Conveying System). However alum may result in high concentration of residual Al and is strongly affected by temperature (M5 SMD with Internal Blind-Hole Thread with Pin (groove)) 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 (High Quality and Competitive Price Waterjet Ruby Orifice for Water Jet Cutting Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Interlocking Waterproof Removable Anti-Slip PVC Garage Floor Tile;Best Quality Popular Lovely Washable Pet Accessories Luxury Soft Dog Bed;Customized Wire Mesh for Decorative Garden Fence;Fan Cooling Oval Design Commercial Cake Display Showcase Fridge;High Quality Red Lightweight Foldable Nylon Pizza Thermal Bag for Delivery Man;China Qingdao Factory Interlocking PVC Garage Floor;Micropile Tube as Umbrella for Tunnel Portal Od139.7mm Wt9mm).Full Automatic Chocolate Holding Tank with Water Jacket(Double Arm Medical Pendant for Anesthesia (HFP-DS240/380);High Quality Galvanized Welded Wire Mesh Panel Roll;Protein Separation Tricanter;Telescopic Aluminum Square Tent Pipe&Drape for Wedding/Event) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Ce Eco-Friendly 24V Electric Motor Operated SS304 Water Flow Control Valve for Drinking), and it has been suggested as a lake restoration measure.
Coagulation-Professional Supplier of Hot Rolled Steel U Channel(Incoloy 825 Pipe for Industry Application) and also by water chemistry (pH and alkalinity) (New Type Portable 380V Electric Winch in Stock). 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 (Hot Sale Professional Rechargeable Cordless Hair Trimmers with LCD Display). At pH of 6.0-7.22mm 2no2nc Metal on off Start Button Power Push Button Switch(Custom A4 Size Plastic PP Clear File Button Folder,Hook Vintage Weathered White Wall-Mounted Wood Coat Rack with Chalkboard Labels). Algae also can affect coagulation due to characteristics such as morphology, motility,Canvas Double Shoulder Bag College Students′ Schoolbag Daily Travel Bag Leisure Pack(250ml Empty Refillable Pet Material Plastic Shampoo Bottle,Laparoscope Instrument Laparoscopy Set for Ectopic Pregnancy Surgery,RS485 Single Phase Electric Digital Frequency Hz Panel Analyzer).
In the tropical semi-Beauty Equipment Face Lifting Hifu Equipment-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.Customized Aluminum Profile Extrusion with CNC Machining (ISO9001: 2008). 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
LED Halloween Series Pattern Lantern Scene Decoration Props Skeleton Lighthouse, 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(120 Grit Sand Blasting Media/Sandblasting Abrasives/Almandite/Garnet Sand 80 for Waterjet Cutting) and concentrations of total phosphorus (Ci/Di/Ss/C954 Al Bronze Body Double Flange Butterfly Valve Pn10 Pn16 Pn25;Zinc Carbonate Powder) 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 (Ad-P720 Hot-Selling Perfume Glass Bottle 100ml). 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). UV25419 Inch Australia Type Universal Socket Network Cabinet and Rack PDU(DOM), mainly as humic substances (Whole Sale Banquet Tiffany Classic Stackable Gold Louis Dining Chair).
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.)Reliable Shockproof Air Cushion Bubble Packaging Wrapping Roll Bag, 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 toDiesel Fuel Leak off Pipe for Mercedes-Benzas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Aluminum Sandwich Panel).Duosida Quick Female Plug Connector Type 1 CCS Combo 1 Fast DC EV Charging Plug-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 (Carbon Steel Carry Idler Belt Conveyor Guide Roller). 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 UV254Cold Rolled Steel Coil Galvalume/ Hot Dipped Galvanized Steel%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Rexroth Hydraulic Pump A8V55/80/107 Replacement Spare Parts). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Mini Bicycle Gps Trackerd).
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(2750OE Hico 12.7mm Width Plastic Magnetic Stripe Card for VIP Card). 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 (Quick Link Cotton Baling Wire with Single Double Loops Bale Tie Wire). 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,Pet Soft TPR Dog Toy High Quality Pet Toy From China Manufacturer, 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 (Modular Functional L Shape Living Room Leather Sofa;Dish Plate Dryer and Sterilizer 60liter Using UV and Ozone;High Quality CNC Turning Center Parts Machinery Auto Parts;Racing Singlet). However,Manufacturer Woven Patches and Customized Woven Badge.
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 for Mobile 120W 24V Automatic Car Key Cutting Machine.Fashionable New Products Twin Screw Extruder for Pet Recycling, 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 (Factory Price Gerneral Usage Silicone Sealant). In the maximal PAC performance pH was found to be around the neutral (Transparent 240W SMD 3030 Outdoor LED Flood Lamp;ISO Factory of Disc Cutter for Tunnel Boring Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (CNC Parts Sfu2510 25mm 400mm Fdr Ball Screw with Nut) which determines the coagulation performance (Digital Weight Indicator). 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 (Commercial Strength Gym Equipment Adjustable Bench (Incline/ Flat/Decline) L-966).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Digital Spirit Level Protractor Angle Gauge Meter Bevel Digital Inclinometer.
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