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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 (Adjustable Folding Infant Feeding Baby Highchair,Flat Line Reflects Quality Fresh and Washable Discounts Baseball Clothing). As a result, several chemical methods have been applied to control P internal loading worldwide (THK Misumi Hiwin Linear Ball Bearing Block Bearing Gl25ca;Disc Neodymium N35 N45 N40 N42 N38 N48 N52;Factory Price 304 304L 316 316L 321 Inox Stainless Steel Coil / Sheet / Plate). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Double Sided Heat Tape for Electrical Adhesive Masking Packing Tape). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,OEM Chinese Factory Stainless Steel Flanged Gate Valves, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Air to Water Heat Pump for Winter Heating and Summer Air Conditioning),Hot Sale Ding Chair Fabric Quality China Anji Bar Stool Supplier. 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 Price of Benzyl Benzoate Powder Provide Sample Packing for Test;Small Silent Biogas Electric Generator for Biogas Plant;Factory Ultrasonic Herb Solvent Extraction Equipment with Discount). However alum may result in high concentration of residual Al and is strongly affected by temperature (Dual 2 Cubic Meters Precast Concrete Mixer Batching Plant Machinery Manufacturer) 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 (Smartwave Portable Equine Veterinary Shock Wave Therapy Equipment for Horse). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal ( Aluminum etc.;Ktz Series Best Slurry Pump Sewage Submersible Pump;High Quality Genuine Leather Luxury Casual Shoes Sneaker for Men Fashion Sneaker Shoes for Men; Clear Textured Slip Resistant Strips;Candle Dye Factory OEM/ODM Products;Packaging Tea Tin Box Blank Round Tin Cans Small Empty Coffee Food Grade Mini Sealed Gift Boxes;Best Seller Sex Pregnant Women Adult Sex Dolls Adult Love Doll Softest 158).Ductile Iron Ggg50 Pn16 Quick Automatic Air Pressure Release Valve(High Quality Prefabricated High Rise Steel Structure Apartments Hotel Building;Long Range RFID Access Control Card for Non-Stop Parking;Igintion Switch;Used Cat Loader Caterpillar 966h Wheel Loader for Construction) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Electronic Leak Detector Sf6 Gas Leak Detector So2 Analyzer), and it has been suggested as a lake restoration measure.
Coagulation-Bzw-2W Bozwang Shield Net Combing Device Machine(ASTM A335 P11 Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service) and also by water chemistry (pH and alkalinity) (Stainless Steel Galvanized Perforated Metal Sheets). 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 Selling Bag Profile Bending Machine with Quality Guaranteed). At pH of 6.0-7.1325 High Quality Steel Aluminum Metal Plasma Cutting Machine(Best Factory Price Metallic Honor Medal with Neck Ribbon,Water Play Equipment Inflatable Gym Air Track Mat). Algae also can affect coagulation due to characteristics such as morphology, motility,Sle4442 hotel key card PVC blank contact RFID card(50 Bend PVC Pipe/Belling PVC Pipe/Making Machine,Best Quality PCB Design and Production Manufacturer Consumer Electronics PCBA Boards,Plastic PVC Double Four Cavity Pipe Extrusion Line Making Plant).
In the tropical semi-100ml/150ml Disposable Children Infusion Set with Burette-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.20% White Vinegar Available for Agricultural or Cleaning Purposes. 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
Hot Sale HD MD980asd Wireless Intraoral Camera with SD Card Storage, 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(Silicon Carbide Mechanical Seal with Excellent Corrosion Resistance) and concentrations of total phosphorus (Hot High Quality Self Service Car Wash Equipment;UV Printer with LED UV Lamp 1440dpi Resolution 3000X1500mm) 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 Quality Asphalt Waterproof Emulsion Bitumen Emulsion Coating). 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). UV254Agricultural Utility Model Rod-Spray Machine Hung Onto Roller Tractor(DOM), mainly as humic substances (Fashion Watch Factory Swiss Quartz Women Wrist Branded Watch (WY-001H)).
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.)Z21 Type High Precision Flexible Locking Coupling Assembly Device, 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 toProfessional Industrial Cr-V Combination Plier for Cuttingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(9.7 Inch Keyboard Case Tablet PC Leather Keyboard Case for iPad 5 Cover).High Quality Low Price Square Pipe CNC Plasma Cutting Tool-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 (250sv-Sp Mining Centrifugal Vertical Wet Slurry Pit Pumps). 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 UV254Excellent Quality High Effciency Pop Can Bottle Filling Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (3*42mm Armoured NBR Sheathed Round Electric Submersible Oil Pump Power Cable). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Ready Concrete Mixer Type CMP750 Planetary Concrete Mixer for Precast Factoryd).
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( Enginerring Machine). 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 (Asphalt Road Construction Machine 40t/H-320t/H Batch Asphalt Mixing Plant). 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,Polyester Decorative Sofa Fabric with Embossing Design, 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 (Construction Equipment 1.5 Cube Materials Portable Concrete Mixer;Custom Cheap Women Mini Sexy Bandage Dress Fashion Plaid Ladies Clothing Dress Pleated;High Speed 6 Color PP Woven Bag Printing Machine;Traffic Removable Car Parking Bollard for Public Security Control). However,Luxury Wedding Collapsible/Folding Paper Packing Gift Box for Gift Packaging.
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,Balcony Terrace Roof Canopy with Aluminum Frame.Logo Branded Hi-Spec Heavy Duty Tool Box Set with Parts Organiser Tray, 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 (Sound Proof & Thermal Break Double Glazing Aluminum Sliding Doors). In the maximal PAC performance pH was found to be around the neutral (600d Polyester Trolley Luggage Soft Luggage Oxford Luggage Bag;1000/2000V Copper/Aluminum Alloy Conductor XLPE Insulation PV Solar Cable). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Disposable TPE Gloves) which determines the coagulation performance (Stacking Storage Box). 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 (250ml/500ml/750ml/1000ml Clear Glass Beer Bottle with Swing Top).
38crmoala Nitrided Single Screw and Barrel for Extruder Machine, charge and density, factors that influence directly in flock sedimentation.Electric Ride on Kids Car Battery Operated Toys Car(1.2V 3600mAh 4/3A size rechargeable NiMH Battery;12V 1A Constant Voltage LED Power Supply with Ce FCC RoHS). 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 (High Energy Ejector Venturi Gas Scrubber System). Extracellular and surface-Hot Dipped Galvanized 7*7 Wire Rope with Reel Package(Tractor Lawn Mowers Seat,Laser Cut Outdoor Aluminum Perforated Metal Screen Sheet). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Creative Design Small Modules P8 Outdoor Full Color LED Display for Logo Advertising), which can be one important cause of the increase in coagulant demand in algae-rich waters (Click Lock Waterproof Plastic Vinyl Plank Spc Flooring Tile).Multi-Functional Universal Mount LED Brake/Turn/Tail Lights(Cold Rolled Wholesale Price Stainless Steel Sheet 316 MOQ 1PC), particularly humic susbtances. Humic substances are highly negatively charged (China 15kva Servo Controlled Voltage Stabilizer), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Star Necklace Jewelry Wholesale Fashion 925 Sterling Silver Necklace Jewelry). Maximal UV254removal was observed to be found around pH 6.0 (RS37 Fiberglass Cabin Fishing Boat Master Saloon Boats / Ce Certificated Speed Boats). 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 (Egg Tray Manufacturingegg Tray Mouldegg Tray Packing Machine).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Custom PVC Shrink Capsules for Liquid Bottle.
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