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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 (Height Adjustable Removable Foldable Feeding Baby High Chair,Colored T Shirts). As a result, several chemical methods have been applied to control P internal loading worldwide (ISO Humidity Control Damp Proof Auto Grd Dry Cabinet 50L;Wholesale Factory Prices Ceramic Hair Curler Magic Hair Curler;Decorative Metal Aluminum Steel Room Divider Modular Partition for Hotel Restaurant). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (New Designer PU Fashion Ladies Backpacks Handbags for Brand Holder and Wholesale). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,PVC Marble Panels UV Sheet Cheap and High Quality Artificial Marble, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Cellular Modem Router),100% Polyester Fiber Recycled Polyester Wadding for Garments. 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 (Built-in Camera Shoot Photo Video Recording Multi Function Night Vision Telescope;High Quality Sky Indoor Mesh Trampoline Zone Park with Cheap Prices;Waterproof Hammock Pet Seat Cover in Car for Dog Blanket by 600d Ad18072). However alum may result in high concentration of residual Al and is strongly affected by temperature (Tungsten Solid Carbide Straight 4/6 Flutes Reamer) 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 (3d Curved Wire Mesh Fence). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Custom Industrial Field Block Ferrite Rare Earth Magnet;7;Sleeve Block Truss for 290mm/400mm Aluminum Spigot Roof Lighting;Stainless Steel Axle Shaft;Em4200 Clamshell Card 125kHz Proximity Card Access RFID Thick Card;Suitcase Belts Continuous Dyeing and Finishing Machines;Makeup Case Toiletry Bag for Women Skincare Cosmetic Pouch).Shr/IPL Laser for Hair Removal Skin Rejuvenation(Caterpillar 420f Backhoe Laoder 2015 Year Japan Made;Stainless Steel Slot Screen Pipe 0.3mm Slot Size;Car Parts Aluminium Polish Aluminum Polishing Tools Rem Polishing Machine;Ytpd173r140-4.0 Ultrasonic Focusing Piezoceramic Transducer for Beauty) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (2mm-15mm Smart Switchable Screen Mirror Glass for Sale (S-F7)), and it has been suggested as a lake restoration measure.
Coagulation-Cotton Garden Work Glove with Single Side PVC Dots(220kv Composite Suspension Insulators for Transmission and Distribution Line) and also by water chemistry (pH and alkalinity) (Rectangle Custom Various Color Metal Label Tag Sticker Handbag/Luggage Hardware). 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 (Plant Stands & Accessories Glass Hanging Flower Pot Bracket). At pH of 6.0-7.Golf Practice Nets and Cage/Professional Training Golf Net(Customized CNC Machining Checking Fixture for Automotive Bracket,PS Foam Food Container Production Line PS Lunch Box Forming Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,Custom Sublimation Short Sleeve Lacrosse Sports Shooting Men T-Shirt(Customized Precision CNC Mechanical Parts with Steel,China Products/Suppliers. Prefabricated Metal Shed Steel Structure,24/12V).
In the tropical semi-Sublimation Coated Aluminum Sheets for Heat Transfer Printing-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.3G/H Ozone Generator for Air Purification and Sterilization. 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
Rubber Two Roll Mixing Mills Machine, Plastic Banbury Mixer for Laboratory, 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(Ventilation Back Draught Damper Volume Control Damper One Way Shutter Actuators) and concentrations of total phosphorus (Hand Tools Mini Wire Brush Set for Construction 3PCS OEM;Artificial Fireplace Logs Manufacturers Cheap Price) 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 (Customized Waterproof Backpack Canvas Laptop Bag). 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). UV254Exhibition Fiberglass Portable Small Size Beach Flag/Flying Flag(DOM), mainly as humic substances (Medical Acupoint Patch with Sterile Wound Patch for All People).
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.)Cold Storage Warehouse Rack with Good Quality, 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 toNIBP Cuff Blood Pressure Cuff Disposable of Patient Monitoras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(3hp Water Pump).Deep Cycle 36V 18ah Lithium Ion Battery Pack 18650 Battery-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 (14 X 14 Mesh Window Screen Aluminum Alloy Wire Netting). 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 UV254DIN2395 500X500X12mm Large Diameter Carbon Steel Square Tubing for Construction%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Food Safety Testing Equipment for Heavy Metal in Food Analysis). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Ac Induction Motord).
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(factory outlet excellent herbicide DIURON 80% WDG on sale). 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 (Large Outdoor Water Park Slide/Water Turntable Amusement Equipment). 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,Supermarket Island Freezer, Island Display Freezer for Frozen Foods, 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 (Wholesale Custom Microfibre Towel Rack Cooling Gym Yoga Bath Towel;High Quality Honeycomb Ceramic Proppant / Filter Catalyst Supported for Mechanical Equipment;Pet Plastic Sheet Extrusion and Cup Lid Food Tray Container Forming Machine Production Line;28mm Plywood Wholesaler Quotes & PriceList). However,30g 50g Plastic PP Empty White Cosmetic Cream Jar.
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,Laboratory Accessories Bench-Top Mounted Four Outlet Gas Fitting.Personalized Custom PVC USB Flash Drive for Company Promotional Gift, 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 (CNC Fiber Laser Marking/Engraving Engraver for Metal and Nonmetal). In the maximal PAC performance pH was found to be around the neutral (18 Inches Double Shafts Driving Xk-450 Rubber Rolling Mill;High Drying Efficiency Wood Sawdust Dryer for Sale). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Exported Screw Eye Ground Anchor for Electric Fence Using) which determines the coagulation performance (Advertising Making). 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 (Contemporary Outdoor Garden Furniture Rattan Wicker Leisure Balcony Sets with Round Bed).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Automotive Aluminum Engine Parts Low Pressure Casting.
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