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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 (Black Bracelet Leather USB Drive Free Design Logo,castironmaria). As a result, several chemical methods have been applied to control P internal loading worldwide (SS304 Stainless Steel Tube Rectangular/Square Tube;The Lowest Price 27er/29er Carbon Fiber Mountain Bike Bicicleta;Hot Sale High Grade Popular Jacquard Curtain Fabric for Living Room/Bedroom). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (New Product Ideas Wooden Musical Jewelry Storage Box). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Anti-Corrosion 1.5mm FRP Roofing Skylight Fiberglass Sheets, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Grade UHP 450mm Graphite Electrodes UHP 18′′x72′′ Graphite Electrodes),Light Blue Color Glass Drink Bottle for Beer. 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 (21/24/27 Speed/ Aluminum Alloy Carbon Frame Mens Bicycle Manufacturer Bikes for Adult;Soft Tube Plastic Cylinder Round Bottle Screen Printing Machine Silkscreen Machinery;Large Music Controlled Colorful Laser Water Fountain). However alum may result in high concentration of residual Al and is strongly affected by temperature (Anti-Corrosion Coated Line Pipe/Seamless Steel Pipe for Oil) 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 (Electric Single Phase Fan Motor 220V 85W with Plastic Cooling Fan). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (1/2 CRV Industrial High Quality Quick Release Ratchet Handle Wrench;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;Upal Cheap Folding Steel Gazebo Tent with PVC Fabric Roof;m.ldkchina.com;5r 200W LED Moving Head Beam 3 in 1 Stage Lighting;250ml Medical Transparent Ultrasound Ultrasonic ECG Gel Wholesale Price).Complete Wood Pellet Line Sawdust/Straw/Biomass Pellet Plant(Top Supplier Lcoe Cost Down 1500V Dual Glass 320W 330W 340W Poly Solar Panel;Hybrid Power System 150kw Electricity Generating System with Battery Bank;Automatic Plastic Fork Spoon Knife Serviette Cutlery Packing Machine;Customzied SKD11 Shear Blades for Leather and Plastic) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes ( Keyboards), and it has been suggested as a lake restoration measure.
Coagulation-Stainless Steel Sanitary Pipeline Three-Stage Emulsion Mixing Pump(10kv Xple Heat Ahrinkable 1-Core Outdoor Termination Kit (Section 500~630 mm^2)) and also by water chemistry (pH and alkalinity) (Aluminum/SS304 Material Bathroom Mirror and Satin Shower Glass Sliding Door Handle). 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 (Good Ventilation Fully-Auto L-Bar Sealer Shrink Tunnel for Software). At pH of 6.0-7.100W 120W 150W COB LED Street Light Housing(Sermorelin Powder Anabolic Raw Powder for Human Grow Hormone,Beautiful Lvt Eco-Indoor Wood Grain Click Planks Vinyl WPC Flooring). Algae also can affect coagulation due to characteristics such as morphology, motility,15 Years Factory OEM Plastic Injection Molding Kid Learning Machine Parts(Ae Bifacial Solar PV Panel 270W Poly German Quality,Long Rod Electrical Suspension High Voltage Polymer Insulator,Diesel and Oil Heated Car Spray Paint Booth Auto Painting Equipment Heated Paint Booth).
In the tropical semi-Air Bubble Stone as Ozone Diffuser for Air Pump-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.Solar PV Detached 30W 12inch Roof Mount Solar Ventilation Attic Vent (SN2014003). 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
Purity Veterinary Pharma Grade Albendazole with Competitive Price, 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(Custom Black-White Printed Product Operation Instruction) and concentrations of total phosphorus (Spdt Floating Valve Motorized Zone Valve for Water Pressure Regulator;OEM Sand Casting Part Slag Ladle for Mine Casting) 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 (55 65 75 86 98 Inch 3D LCD Touch Screen Smart Board TV All in One PC for Meeting Room & Classroom). 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). UV254Trailer Part Coupling, ISO 7241A Quick Release Coupling Qrc 1/2′′npt(DOM), mainly as humic substances (Soft Touch 22 Inch Reborn Silicone Baby Doll Kits).
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.)Black PU Auto Car Neck Rest Car Seat Headrest Neck Pillow, 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 toFacial Cleaning Cellulose Sponge for Cosmetics Makeup Brush Cleanas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(A4 Double Sides Mini Teaching Writing Dry Erase White Board for Kids).Receipt Book/Invoice Book/Business Form Book-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 (Large Lifting Force Detachable Hydraulic Drilling Rig Machinery for Sale). 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 UV254Best Price Lifting Face Body Shaping Portable Anti Cellulite Laser Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Good Quality White and Brown Paper Soup Containers). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Two Post Parking Liftd).
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(Convenient Operation Sludge/Aluminium Powder Briquettes Making 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 (Commercial Lighting Hotel Bar LED Track Lights). 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,Comfortable and Soft Cat Pet Bed Pet Supplies Mini House for Cat, 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 (Women′s Mesh Contrast Pleat Fashion Black Tank Top;130 T/H Water-Cooling Vibrating Grate Cotton Fired Boiler for Power Plant;24-410 White PP Plastic Land Seal Pivot Spout Caps for HDPE Cylinder Bottles;High Brightness Neon Tube Swimming Pool LED Strip Lighting). However,Standard Vertical Rotary Automated Smart Tower Car Parking System.
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,Stainless Steel Water Filter Housing RO Systems.Vertical Automatic Computer Control Roll Slitting Rewinding Machine for BOPP, 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 (Kayal Best Quality 4 Pins 5 Pins Auto Relay 12V). In the maximal PAC performance pH was found to be around the neutral ( Auto Seal Stainless Steel Travel Mug Cup (SH-SC36);Port Bulk Cargo Tire Mounted Truck Loading Dust Control Eco-Hopper). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (VRLA Deep Cycle Storage Battery 12V 100ah (QW-BV100A)) which determines the coagulation performance (Products). 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 (Customized Lift Gas Support Spring with Metal Eyelet End Fitting).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Textile Machine Parts Multiple Pattern Box.
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