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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 (Ribbed Colorful Wall Plug Anchor with Screw,Electric Magnet Latching Relay Alarm Circuit PCB Relay 100A for Smart Meters). As a result, several chemical methods have been applied to control P internal loading worldwide (Modern Living Room Wood Frame Genuine Bonded Leather Chesterfield Sofa;New Baking Tool Creative Customized Silicone Toast Cake Mold;150-1000kg Commercial and Restaurant Cube Ice Maker Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Littlefuse IC Fuse Cartridge Ceramic Electronic Component Nanosmdc012f-2). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,CCTV Security System Projects IP Camera Factory Hikvision IP Camera, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Customized Factory Supplier Metal Pressing for Machine),Eco-Friendly Euro Plastic Container with Lid. 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 ( AC4900ca;Carbon Steel Heavy Structural Flat Washers Grade 10 DIN6916 Washers;Waterproof Antislip PVC S Mat PVC Z Mat for Bath Swimming Pool Factory Price). However alum may result in high concentration of residual Al and is strongly affected by temperature (Steel Drilling Water Well Filter / Bridge Slot Screen Pipe) 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 (Hydraulic Scrap Metal Baling Machine for Metal). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Astma312 TP304/Uns30400/X5crni18-10 Seamless Stainless Steel Round Hollow Bars;C-Type 2 Piece Tin Can Making Punch Press Machine;Biobase -10~-25 Degree Upright Style Single Door Lab Deep Freezer;Powerful Bass and Nosie Cancelling Over Ear PS4 Gaming Headphone with Mic/Mute and Volume Control;1800W Cooling Capacity Water Chiller (CW-5300);Custom Ductile Iron Casting Parts Gray Iron Sand Casting;High Quality Sand Paper for Sand Machine Brush (YY-170)).2.7 Inch 16X2 Character 1602 LCD Display COB LCD Module 16*02 16*2 LCD 2.7′′(Portable Trade Show Stand Tension Fabric Event Backdrop Display Stand From Tianyu;Engineering Plastic Material;Pet Hot Stamping Aluminium Foil for All Cards;SAE 100 R1 R2 1sn 2sn Hydraulic Hose Assembly Fittings) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (GMP Certified Collagen Softgel for Fish Collagen), and it has been suggested as a lake restoration measure.
Coagulation-Professional Stage Lighting 7PCS 4in1 LED Flat PAR Lights(26000lm 200W LED High Bay Lamp Fixture for Gym House Factory) and also by water chemistry (pH and alkalinity) (Luzhong-700 70HP 2WD Two Wheel Drive Farm Tractor). 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 (Wholesale Hot Pressed Waterproof Wear Anti Slip 5D Car Mat). At pH of 6.0-7.Stainless Steel/Brass/Copper/Carbon Steel Woven Wire Mesh with ISO Approved for Filtration(Hjd-J3 Double-Position Semi-Automatic Heat Transfer Machine,Corn Starch Foam Biodegradable Frozen Food Packaging Tray). Algae also can affect coagulation due to characteristics such as morphology, motility,Standard Air Small Sandblaster for Construction Machinery Cleaning(Good Quality of 60t/D Wheat Flour Milling Plant,Energy Saving One Step Automatic Tritan Pet Blow Molding Machine,Best Ammonium Chloride High Quality Products).
In the tropical semi-Common Mode Choke, Transformer Used for Power Supply, EMC, Torodial Coil, UL, Ce, VDE,-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.Customized Dust Filter Cartridge Price for Industrial Welding Fume. 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
Chinese New Crop Watermelon Seeds Big Size Water Melon Seeds, 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(Heavy Duty Galvanized Stacking Steel Pallet Shelving with Posts) and concentrations of total phosphorus (Potato Chips Design Non-Toxic Silicone Baby Teether Toy;686zz Miniature Deep Groove Radial Ball Bearings) 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 (OEM Stamping Parts Aluminum Profile Stamping for Child Safety Seats). 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). UV254Standard Sizes Aluminium Galvanized Mild Steel U Channel(DOM), mainly as humic substances (Automatic Fresh Fruit Juice Bottle Natural Fruit Canning Machine).
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.)Linyi Jianzhong Square Veneer Tube Dryer Wood Veneer Dryer Machine for Plywood, 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 toFull Automatically Wp Line Powder Jet Mill Micronizer in Agriculture Fieldas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Polishing Pad For Floor).Rubber Raw Material Kneader Machine -75L Banbury Mixer-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 (Power Transformer Voltage Transformer Pq2620 Series High Frequency Transformer). 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 UV254Small Industrial Sewage Treatment Unit for Industrial Wastewater Treatment%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Exdiibt4 Explosion Proof Type 10kw Power Inverter Built in Low Frequency Transformer). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (ASTM A516 304 310S Bimetal Titanium Stainless Steel Composite Plated).
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(American Double Hung Thermal Break Aluminum Window in China). 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 (Best Industrial Coal Fired Steam Boiler Manufacturer in China). 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,Hot DIP Galvanized Scaffolding Hook-on Ladder Ringlock Scaffolding with Hooks (RML), 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 (Luxury Modern Bathroom Furniture Sanitary Ware Solid Surface Basin;Monofilament Fishing Tackle Green Nylon Fish Net;Used Fashion Summer Children′s Dress Unsorted;Disposable Custom Printed Food Kraft Paper Box for Salad/Soup/Noodle). However,Wire to Board Spring Type Connector Sy141-2.54mm Made in China.
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,100% Cotton Dobby Terry Salon Towel, Debossed Hotel Towel, Animal Towel.Naixer Ice Cube/Bullet/Tube/Block Ice Maker/Ice Making Machine for Sale with Ce, 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 (Longboard or Skateboard Ball Bearings 608zz 608-2RS). In the maximal PAC performance pH was found to be around the neutral (High Speed Automatic Facial Tissue Paper Middle Bag Packing Production Line;1000kg/Day Ice Making Machines Custom Ice Cube Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (CNC OEM ODM Customized Car Housing Parts Machining Parts) which determines the coagulation performance (Barite Vertical Mills For Sale Wholesaler Quotes & PriceList). 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 (Custom Full Color Printing PP Table Mat Plastic Mat for Kitchen).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Ring Die Sawdust Wood Pellet Making Machine Line.
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