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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 (Scaffolding Board Cable Tray Panel Roll Forming Machine Line,Sunglass Cloth). As a result, several chemical methods have been applied to control P internal loading worldwide (24000L Chemical Corrosive Poisonous Liquid Tank Container with ISO Csc;Fiberglass Mesh/Fiberglass Mesh Cloth/Fiberglass Netting Mesh;No Pollution Ce RoHS 30W Indoor UV Insect Killer Lamp Fly Mosquito Glue Trap Catcher). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Copper Standard Multi 2/4/6/8 Cores Alarm Cable Security Monitor System). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Disposable Polypropylene Protective Head Wear Bouffant Cap, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (ISO9001 Certification of High Quality Manufactured Professional CNC Turning Parts),Plastic Injection Molding Machine for Nylon Cable Tie Mould Making. 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 (Textile Mill Food Industry Garment Factory Oil Gas Steam Boiler;V4 Type Sintered Porous Filter with Female Thread;PVC Stripe Anti-Slip Door Mat with Color Logo). However alum may result in high concentration of residual Al and is strongly affected by temperature (1200*2200mm Black Powder Coated Dutch Barn Stall Door) 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 (China Disposable Pillowcase Hospital Bed Cover for Adults). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Hot Sale Custom Ski Goggles Snowboard Goggles Straps Anti-Glare Ski Glasses Snow Goggles UV400;Hydraulic Scrap Metal Baling Machine for Metal;Black Bracelet Leather USB Drive Free Design Logo;SS304 Stainless Steel Tube Rectangular/Square Tube;cleaning Pressure Compensating Dripper;The Lowest Price 27er/29er Carbon Fiber Mountain Bike Bicicleta;Hot Sale High Grade Popular Jacquard Curtain Fabric for Living Room/Bedroom).Hotel Dental Kit Toothbrush Shaving Kit Razor Amenities Sets(New Product Ideas Wooden Musical Jewelry Storage Box;21/24/27 Speed/ Aluminum Alloy Carbon Frame Mens Bicycle Manufacturer Bikes for Adult;Good Quality Welding Electrode E6013 E7018 E6011 E6010;Soft Tube Plastic Cylinder Round Bottle Screen Printing Machine Silkscreen Machinery) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Large Music Controlled Colorful Laser Water Fountain), and it has been suggested as a lake restoration measure.
Coagulation-Factory Price Gerneral Usage Silicone Sealant(Anti-Corrosion Coated Line Pipe/Seamless Steel Pipe for Oil) and also by water chemistry (pH and alkalinity) (1/2 CRV Industrial High Quality Quick Release Ratchet Handle Wrench). 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 (Plastic Led Downlight). At pH of 6.0-7.Yonglian Yl003f European Standard Power Cord with VDE Certificate Approved(Wood Acrylic Ss CO2 Tube CNC Laser Cutting Machine for Metal and Nonmetal,SKF NTN Chik Koyo Deep Groove Ball Bearings 6308 Zz Ball Bearing Turbo for Sale 40*90*23mm). Algae also can affect coagulation due to characteristics such as morphology, motility,High Manganese Casting Nordberg Gp100 Mantle Cone Crusher Parts(Upal Cheap Folding Steel Gazebo Tent with PVC Fabric Roof,5r 200W LED Moving Head Beam 3 in 1 Stage Lighting,m.bmspd.com).
In the tropical semi-Manufacturer New Design Reusable Clear Lalique Glass Perfume Packaging Bottle-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.Xinjing Wide-Mouth Kitchen Glass Square Jar for Spice, Seasoning. 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
Dn100 4 Inch Rubber Seal 220VAC Wafer Type Electric Actuator Butterfly Valve, 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(Hybrid Power System 150kw Electricity Generating System with Battery Bank) and concentrations of total phosphorus (Customzied SKD11 Shear Blades for Leather and Plastic;Die Casting Prototype Supplier & Manufacturer) 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 (Aluminum/SS304 Material Bathroom Mirror and Satin Shower Glass Sliding Door Handle). 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). UV254HDPE PE Pipe Production Line/ PPR Pipe Production Line(DOM), mainly as humic substances (Sermorelin Powder Anabolic Raw Powder for Human Grow Hormone).
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.)Shenzhen Customized Metal Stamping Parts Fabrication Service, 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 toChemical Vacuum Coating Single Stage Rotary Piston Pumpsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(90 Square Meters Modular Prefabricated Prefab Shipping Container House.).High Tensile Wire Rope Lifting Jaw Jaw Turnbuckle Rigging-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 (Spdt Floating Valve Motorized Zone Valve for Water Pressure Regulator). 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 UV254Desktop Digital Servo Control Universal Material Tensile Testing Machine 8201s%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (High Precision Die Cutting Machine Packaging Flatbed Cutter Vct-MFC6090). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (China 3 Horse Angle With Standard Styled).
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(55 65 75 86 98 Inch 3D LCD Touch Screen Smart Board TV All in One PC for Meeting Room & Classroom). 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 (Soft Touch 22 Inch Reborn Silicone Baby Doll Kits). 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,UV Digital Flatbed Printing Machine Seiko-1024, 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 (Toner Cartridge Chip for Ricoh Aficio MP C3002 3502 (841735~841738 841647~841650);Facial Cleaning Cellulose Sponge for Cosmetics Makeup Brush Clean;7 Inch Ultrasonic Digital Video Reverse Parking Sensors for Truck;Aluminium/Aluminum Foil 8079-O 7 Microns for Lamination Grade). However,10-30V LED Combination Lamp Stop, Tail, Indicator, Reverse Trailer Lamp Truck Light.
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,Topkit Tower Crane Rct6011-6 for Construction Building.200m Deep Top Driving Tractor Mounted Water Well Drill Equipment, 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 (Slip on Blind Weld Neck Stainless Steel Flange Including Welding Neck Flange). In the maximal PAC performance pH was found to be around the neutral (Large Lifting Force Detachable Hydraulic Drilling Rig Machinery for Sale;Good Quality White and Brown Paper Soup Containers). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Sf606 Serve Motor Automatic Wood Cut off Saw Machine) which determines the coagulation performance (Multi-Function Hand Disinfectant Gel). 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 (Convenient Operation Sludge/Aluminium Powder Briquettes Making Machine).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Tz03D High Quality China 20-40HP Garden Tractor Front End Loader Hot Sale in New Zealand.
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