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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 (Three-Phase Electronic Multi-Function Watt-Hour Current Meter,Optical Parts Microscope for High Resolution Optical Microscope Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (Valve Wheel Adjustable Hydraulic Impact Torque Wrench;Fashion Double Striped Non-Slip Entrance Mat;Sofa Cushion Wholesale Customized Pillow Cover Home Decorative Throw Pillow). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (DC Colorful Battery Operated Small Hand Fan for Outdoor Use). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,30L 600W Dental / Lab Ultrasonic Cleaner Washer Ultrasound Cleaning Machines, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (54303-ED50b 333391 Front Left Japanese Cheap Shock Absorbers for Nissan),G95 LED Filament Bulb Light Lamp 8W 110-130V/220-240V Edison Bulb with Ce RoHS. 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 (1 Inch Dn25 2 Way Brass Male Thread Electric Control Water Motorized Ball Valve;TPR Vibration Protection Cut Resistant Safety Work Glove for Industrial Purpose Use;Wholesale Comfortable Men′s Winter Leather Snow Boots). However alum may result in high concentration of residual Al and is strongly affected by temperature (Promotion Cheap Woven Wristbands Event RFID Woven Wristband) 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 (Large Slewing Rings Bearings for Wind Turbine Ring on Sale). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Non Woven Wheel for Stainless Steel Polishing and Grinding;High Quality Free Sample Woven Label for Garment Accessories;Rls9 Zz-2RS Ls11 Lj-1-1/8 Cixi Inchi Wheel Roller Ball Bearing;Shenzhen Customized Metal Stamping Parts Fabrication Service;Products;Narrow Hub Connection Brake Discs for Sprockets (TLK603 RLK603 55X110);Precision Aluminium 6061 CNC Machining Parts for Baffle Bulkhead Flow Valve (F-155)).Lockey Loto Durable Standard Safety Gate Valve Lockout with Ce(Micron Circular Stainless Steel Filter Disc;PVC Marble Panels UV Sheet Cheap and High Quality Artificial Marble;Indoor Trampoline Climbing Tower with Slide;China New Technology Swimming Pool Heat Pump (MDY50D)) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Agriculture Machinery Belt Banded Cogged V-Belt), and it has been suggested as a lake restoration measure.
Coagulation-FRP Fiberglass Underground Septic Tank for Effluent Treatment(Nonwoven PP Fabric Nonwoven Needle Punched Geotextile) and also by water chemistry (pH and alkalinity) (12-288 Core Single Mode Loose Tube Fiber Optic Cable with Aluminum Tape). 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 (Customized Plastic Injection Mould Products Industrial Parts PVC Plastic Bend Elbow). At pH of 6.0-7.Pgz1000 Crystal Industry Pneumatic Scraper Bottom Discharge Flat Basket Filter Centrifugal Separator(Sancore Nappa Leather Back Sticker Huawei Mate20/PRO Phone Case,Anti-Aging Dredger UHMWPE/HDPE Sand Mud Oil Dredge Floater Pipe Pipeline). Algae also can affect coagulation due to characteristics such as morphology, motility,Inflatable Floating Water Playground Water Island for Commercial Business Usage(600g Synthetic Fiber Ceiling Filter/Roof Filter/ Roll Filter for Spray Painting Booth,High Quality Galvanized Pan Head Self Drilling Screw,Brownpaperbag).
In the tropical semi-Solid Carbide Straight Slot Reamer with Inner Cooling Hole-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.Balaclava Hood Ski Bike Cycling Face Mask Cap Fleeces Helmet. 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
Commercial Promotion White Inflatable Party Tent for Exhibition, 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(Two Walls Stainless Steel Insulated Straw Cup Step Shape Metal Juice Cup with Straw) and concentrations of total phosphorus (Factory Supply Urban Outdoor Street Mobile Sweeper Road Sweep Truck with Brushes;Mens Slim Fit Cashmere Sweater) 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 (Hotel Wall Mounted Infrared Battery Electric Liquid Automatic Soap Dispenser). 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). UV254Camping Gas Stove, Outdoor Stove, Table Gas Stove(DOM), mainly as humic substances (Jumbo Drilling Rig with Three Arms (HFG-33J)).
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.)Toroidal Power Transformer for Household Audio, 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 toXaja Truck Light Wire Automotive Cable Trailer Wiring Harnessas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Cooking Retort Pouch).Mobile Scissor Lift Underground Car Lift/ Hydraulic Car Lift-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 (ISO Linyi Apitong 28mm Marine Plywood Container Spare 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 UV254Wholesale Fashion Custom Round Neck Mens Tshirts Plain Tshirts for Print%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir ( medical disposable clothes). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Decorative Mirror Stainless Steel Sheet Grade SUS201 ASTM201d).
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(Pneumatic CNC Router 1325 Multi Heads Pneumatic Furniture Cutting 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 ( Welding Parts). 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,Large Lifting Force Detachable Hydraulic Drilling Rig Machinery for Sale, 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 (Ultrasonic Welding Machine for Cutting Sponge Scouring Pad Scourer;Safety Shoes Anti-Slip Silicone Rubber Crampons OEM Factory;Outdoor Artificial Wood Plastic Playground Equipment on Promotion (HK-50011B);Clay pad). However,OEM 15t Conveyor Cast Iron Simplex Duplex Triplex Chain Sprocket Gear.
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,Counter Top Chips Worker Infrared Chips Warmer.100cm Lovely Little Girl Japanese Anime Lifelike TPE Mini Sex Doll, 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 (China Factory Forged Clevis Grab Hook Crane Lifting Hook Made in China). In the maximal PAC performance pH was found to be around the neutral (Food Grade Glass Storage Glass Jar for Spices Candy Foods Dried Vegtables Canned Fruit;LG936 LG938 Front End Loader Parts Gas Spring 29330011391). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Colorful LED Electric Submersible Pond Rockery Fountain Water Pump) which determines the coagulation performance (Stainless Steel Screw Ss304 Torx Drive Self Tapping Screw). 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 (360ml Glassware/Glass Bottle/Honey Jar/Jar for Bird′s Nest).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Cheap Ghost Clear Transparent Acrylic Napoleon Chair for Wedding.
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