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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 (Dumpling Wrapper Machine Dough Pressing Machine Dough Sheet Cutter to Do Tortilla Flat Bread,Medical Water Sink). As a result, several chemical methods have been applied to control P internal loading worldwide (Cow Horse Trailer Ramp Stall Stable Rubber Mat;Hydrochloric Acid (HCl) ;Flexible Aluminum Protecting Rolling Curtain Shield Bellows Cover). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (7 Liters Vertical Type Commercial Butchery Manual Sausage Filler). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Venlo Polycarbonate Covering Material Greenhouse on Sale, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Dog Plush Toy Chew),Preparation Concrete Vibrator Shaft with Japanese Coupling. 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 (Mica Fiberglass Braided High Temperature Electric Power Cable;Manufutuer Promotes Skin Regeneration Repair Anti Aging Smoothing Fine Lines Facial Mask;Portable Animal High Frequency X Radiography Machine (HP-HFX600V)). However alum may result in high concentration of residual Al and is strongly affected by temperature (Customized Mold Design Non-Stick Silicone Waffle Maker Cake Mold) 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 (Cryogenics Milling Stainless Steel Machining Weldment). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Cement Bag Manufacturer Kraft Paper Valve Bag for Cement;Custom Stainless Steel Parts CNC Automotive Device Spare Parts CNC Milling;Popular High Quality Wholesale Felt Christmas Bag Christmas Felt Gift Bag;PC260 3.0-24V 24*27mm 3W DC Motor for Electric Garden Tool;Surface Grinding Machine Manufacturers;LED Dancing Wing Props Halloween Christmas Party Supplies;Glass Shower Door Frame Waterproof Seal PVC Seal).4mm Waterproof PVC Spc Vinyl Plank Laminate Wood Plastic Flooring(2-Channel/4-Channel DC Current Voltage to RS232/RS485 a/D Converter;Cheap Bearing Rotary Fiber Laser Marking Machine Marker Laser Machine for Stainless Steel;1000W/3000W Laser Metal Sheet Fiber CNC Laser Cutting Machine;12mm Multiwall Green Perforated Hollow Polycarbonate Sheet) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Best Quality Tianeptine Acid / Tianeptine CAS 66981-73-5), and it has been suggested as a lake restoration measure.
Coagulation-Activated Carbon Pellet Manufacturer Used for Gas Treatment(Chiller Price Water Cooling System Screw Air Cooled) and also by water chemistry (pH and alkalinity) (1.0m 4CH Wireless NVR Alarm Security CCTV Kit with 10 LCD Monitor 1tb HDD). 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 (Heavy Duty 2.5mm Thickness Expanded Metal Mesh China Supplier). At pH of 6.0-7.New Arrive Jewelry Box for Ring Necklace Factory Custom Made Leather Gift Box( NdFeB Magnet for Motor (N38H),15kg Big Payload Unmanned Aerial Vehicle (uav) with Various Camera Payload Optional). Algae also can affect coagulation due to characteristics such as morphology, motility,OEM Custom 2pieces Car Rims 17 18 19 20inch Forged Car Alloy Wheels(2.4GHz WLAN Signal Booster 2.4G Wi-Fi Internet Wireless Signal Amplifier Repeater Booster,Long Sleeve Safety Working Clothes Professional Safety Working Clothes,Extruded Polystyrene Steel Sandwich Panel Sheet).
In the tropical semi-Indoor High Definition TV Screen P1.667/P1.875 /P1.923 LED Display Wall-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.Top Quality Precision Floor Industrial 2 Ton Weighing Scale. 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
Ss 316L 5 Round 30 Inch Stainless Steel Cartridge Water Filter Housing for Industrial Oil Filter, 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(Safety Belt Polyester for Lifting Sling /Round Sling (NHRS)) and concentrations of total phosphorus (Plastic RGB LED Round Dining Table for Wedding Lights Decorations;Universal Hot Product Stainless Steel 68L CO2 Cylinder) 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 (on-off Automotive Switches Automotive Rocker Switch 16A Rocker Switch). 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). UV254Colorful LED Electric Submersible Pond Rockery Fountain Water Pump(DOM), mainly as humic substances (Ferrous Sulphate Heptahydrate for Water Treatment).
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.)Drainage Rubber Grasss Ground Stabilisation and Play Area Anti Slip Rubber Mat, 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 toHydraulic Valves-Yuken Series Valve-Flow Control Valve- (one-way) Throttleas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Grinding Balls).Chain Link Wire Mesh (Pressure Treated Timbers)-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 (PVC Shrink Sleeve for Glass Bottle Capsule). 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 UV254Metal Pot Scourer Used of Stainless Steel and Galvanized%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (High Energy Wet Pulverizer and Wet Powder Mill). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Environment Friendly Acrylic Silicone Sealant for Building Materialsd).
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(Hot Sale and Good Quality Playground Artificial Lawn for Soccer). 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 (0.7kw Dereike Dhb 220b D70 Air Pump for Central Vacuum Systems). 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,750 GSM Needle Felt High Temperature Air Filter Bag PTFE Fabric, 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 (Pet Strapping Belt Making Machines/Pet Packing Straps Extrusion Machine;Rubber Product Making Machinery / Car Floor Mat Hydraulic Vulcanizing Press;BRT Gasoline Log Splitter 22 Ton Firewood Processor;Leisure Womens Suede Jacket). However,Aluminum/SS304 Material Bathroom Mirror and Satin Shower Glass Sliding Door Handle.
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,CNC Parts Sfu2510 25mm 400mm Fdr Ball Screw with Nut.OEM Aluminum Cutting Welding Stamping Shaping Fabrication, 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 (Fashion in China Tag Watches Men Quartz Water Resistant Stainless Steel Back Dw Watches). In the maximal PAC performance pH was found to be around the neutral (Wholesaler Manufacturer Toasting Utensil Golden Black Non Stick Rectangle Toast Box and Lid;Custom Dye Sublimation Printed Phone Lanyard ID Badge Holder with Logo Custom). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Cotton/Polyester/Spandex Interlock for Clothing) which determines the coagulation performance (SMA Male Plug to N Male Cable Connector for Rg316D Cable Jumper Assembly). 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 (Industrial Gear Driven Concrete Marble Terrazzo Floor Grinding Machine).
Cheaper Polyester Cord Strap Factory Made in China, charge and density, factors that influence directly in flock sedimentation.Fashion Jewelry Stainless Steel Rose Gold Gemstone CZ Ring SSR1948(Custom Promotinal Police Equipment Breathable Mossy Oak Disguise Airsoft Uniform;Cheap CNC Leather Oscillating Knife Cutting Machine Milling Head Knife Head Cutter). 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 (Bh36/Dh36/Ah36 Hot Rolled Marine Steel Shipbuilding Plate). Extracellular and surface-Aluminum Die Casting Mould Industrial Fittings Auto Parts Aluminum CNC Processing(Tie-Up Pants,Z21 Type High Precision Flexible Locking Coupling Assembly Device). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Certified 100% Natural & Pure Organic Basil Herbs Oil), which can be one important cause of the increase in coagulant demand in algae-rich waters (Class125 Double Disc Wafer Swing Check Valve).P3.91 P4.81 P5.95 P10 P16 SMD Front Open Maintenance Billboard LED Display(Wholesale Ground Vulcan Earth Screw Anchor for Rail and Highways), particularly humic susbtances. Humic substances are highly negatively charged (12V Mini Linear Actuator Car Trunk Door Actuator), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Juki Pick and Place 40071585 Head Vacuum Unit Asm for Ke3020 SMT Machine Original New in Stock). Maximal UV254removal was observed to be found around pH 6.0 (Polyethylene Strap Polypropylene Band Pet Packing Tape Pet Strapping Band Making Machine). 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 (Europe Good Quality and Cheap Price High Efficiency Swimming Pool Water Heater Heat Pump).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Throttle Body Valve Plastic Heater Inlet Pipe 55559352 for GM Chevrolet Cruze.
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