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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 (Kitchen Stainless Steel Washing /Wash Double Bowl White Sink,Texture Spray Gun). As a result, several chemical methods have been applied to control P internal loading worldwide (Factory Price 50W LED Corn Bulb E26/E39/E27/E40 Base Indoor and Outdoor Industial Lighting;FRP Insulated PU Foam Composite Panel for Refrigerated Truck Body;Whole-Sale 25cm Cleanroom M3 Wipes Cleaning Tissue Cellulose Wipers). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (1325/1530/2030/2040 CNC Woodworking Router Machine with Cheapest Price and Big Discount Is on Big Sale). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Water-Proof Silicone Coated Fiberglass Cloth, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (ERW Structural Carbon Steel 2.5 Inch Schedule 40 Black Iron Pipe),Poultry Farm Equipment Feeding System Made in China. 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 (Wholesale Portable Travel Bamboo Tooth Brush Holder;Wholesale Brosilicate Glass Smoking with Black Triple Layer /Triple Arm Straight Glass Water Pipe;Stationary Asphalt Mixing Plant From 100tph to 400tph). However alum may result in high concentration of residual Al and is strongly affected by temperature (V9 37kw 220V 380V Various Motor Type Control Flexible and Adaptable AC Drive) 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 (Professional Supply Original Clutch Disc for Daf Volvo Benz Nissan Isuzu All Brand). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Automatic Non-Woven T-Shirt Bag Making Machine with High Efficient;Belt Driven Oil Lubricate H-Pump Reciprocating Two-Stage Piston Air Compressor (RT1.5/12.5); Non-Contact Thermometer Gt750;Personal Skin Care Silicone Sonic Facial Cleansing Brush;Agricultural Machinery 0.8ton Wheel Loader for Sale;UV Coating Surface Treatment and Indoor Usage Plastic PVC/WPC/Spc Flooring Extruder Machine;Hot DIP Galvanized Scaffolding Hook-on Ladder Ringlock Scaffolding with Hooks (RML)).Hydraulic Metal Hole Digger Punching Machine (CH-80)(Customized Thread Cutter of M105*3.0 Large Cutting Tools for CNC Machine Tools;ASTM A53 Black Round Metal Carbon ERW Steel Pipe;Automatic Food Packing Machine for Chocolate Candy Biscuits Snack Food;Motorcycle Parts Motorcycle Brake Caliper and Brake Master Cylinder for Wave110) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Alumina Ceramic Foam Filter for Aluminum Casting), and it has been suggested as a lake restoration measure.
Coagulation-High Temperature Resistant Waterproof Double Sided Industrial Adhesive Transparent Tape(Two Sides Grey Silicon Coated Fiberglass Waterproof Roofing Fabric Cloth) and also by water chemistry (pH and alkalinity) (Supply12HP Copeland Scroll Air Conditioner Compressor Zr144kce-Tfd-522 for Sale). 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 (Auto Bearing 6203llu). At pH of 6.0-7.Painted Black Grade U3 Studless Boat Anchor Chain for Sale(15.6 Slim 30pin Edp Screen LCD Display N156BGA-Eb2 N156bge-Eb2 for Laptop Screen Replacement,Quick Drying Waterproof Silicone Sealant Construction Adhesive Glue for Glass). Algae also can affect coagulation due to characteristics such as morphology, motility,Agricultural Drip Irrigation Rain Gun System(12mm LED RGB String Light/ LED Pixel with SD Card Controller,Coupling Capacitor for No Partial Discharge Signal Detection,High Efficiency Automatic Spray Coating Line for Wooden Door).
In the tropical semi-99.999% Sio2 Quartz Grain Sand 100-200 Mesh for Quartz Rod-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.Joyod Russia Single-Head Double-Station Screw Locking Machine for Lamps, Cellphones, Keyboards. 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
China Factory Gk35 Sewing Machine for Bag with Conveyor, 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(High Precision Machinery Plastic Parts with Injection Mold) and concentrations of total phosphorus ( Type Dlo 2kv Msha;Vacuum Hydraulic Press Rubber Machine for Rubber Silicone Products (KS200VR)) 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 (Auto Styling Car Interior Accessories Central Armrest Storage Glove Trau Box for Ranger). 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). UV254Longboard or Skateboard Ball Bearings 608zz 608-2RS(DOM), mainly as humic substances (Burglar Alarm PIR Microwave Motion Sensor Srdt15).
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.)Durable Use for Clothes PU Synthetic Leather for Garment Eco-Friendly PU Synthetic Leather, 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 toDeep Drawing 300tons Sheet Metal Stamping Hydraulic Press Machine 100tonsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(XP-30A Jet-Grouting Drilling Machine with Flexible Operation Saving Time Cost).Metal Steel Tube Beveling Round Pipe Chamfering 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 (300bar High Pressure Air Compressor with Capacity of 100~500L/Min). 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 UV254Individually Wrapped Paper Straws Compostable Paper Drinking Straws%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (40mnb High Quality 40teeth Grass Brush Cutter Blade). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (As Animal Drugsd).
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(Water Oil Liquid Level Measurement Devices Glass Level Gauge). 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 (OEM Agricultural Combine Painted Conveyor Driving Chain Sprocket). 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,Flanges Male Female Fittings Assembled with Flexible Metal Hose, 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 (Best 1.75mm 3mm ABS PLA 3D Printer Filament Supplier 1kg 5kg for 3D Printing Clear ABS Filament;Manual Brass Button Time Delay Auto Stop Urinal Flush Valve (C-16);High Heat Resistant Silicone O Ring for Thermos/Bottle/Glass Jar;Hot Sale 2000W 60V Fat Tire Wheel Harley Electric Scooter). However,Kiet Brand High Efficiency Automatic Hydraulic Cam Dismounting Puller.
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,Pressure Swing Adsorption Medical Oxygen Concentrator Psa Medical Equipment.Spare Customizable Pultrusion FRP Angle Bar for 50*50*2.8mm, 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 (Bzw-20ts Servo Large Terminal Crimping Machine). In the maximal PAC performance pH was found to be around the neutral (Hot Sell Peptides Follistatin 315 Price--Factory Direct Supply 99% Purity;Car Cooling Spare Parts Compressor Magnetic Clutch). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Jingsun High Efficiency 380W 400W Perc Mono Solar Panel) which determines the coagulation performance (Cereal Bites Moulding Machine High Quality Supplier). 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 (2 in 1 Baby Feeding Chair Kids Eating High Chair).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Speed Sensor 8-97328058-1 Odometer Sensor for Isuzu.
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