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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 (Unistrut Type Slotted Steel Strut Channel or C Channel,1070 O Aluminium Circle). As a result, several chemical methods have been applied to control P internal loading worldwide (China Manufacturer Aluminium Oxide Abrasive Metal Grinding Polish Cutting Disc Wheel for Grinder;1000W Electric Motor Price Lawn Mower Motor Concrete Mixer;Modern design Prefab Steel Structure Livestock Farm for Layer Chicken and Broiler). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Jelly Patent Mirror Face Napa Artificial PU/PVC Leather for Shoes Materials). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Safety Stairs / Pool / Garden / Balcony Laminated Glass Fence with Ce, CCC, ISO9001, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Metal Can 750ml Tin Box Extra Virgin Olive Oil Cans),FDA Approved Disposable Biodegradable Foam Packaging Boxes for Fast Food. 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 (Surgical Drape Angio Pack Angiography Drape Pack;Synthetic Fiber Filter Rolls Filter Media for Air Conditioning;Must 4kw 2HP Pump Power Inverter Ags Bts Available). However alum may result in high concentration of residual Al and is strongly affected by temperature (Prefab Factory Price High-Quality Modern Shipping Container Clinic) 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 (Street Led Lamps). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Comfort Rubber Cow Stable Stall Rubber Matting/Mattress/Mat with Fabric Insertion;Customized Dummy Animal Teething Toy Design Baby Pacifer;KERONG Electronic Keypad Digital Combination Hardware Glass Locks For Lockers′ Safes;High Purity Calcined Alumina Micro Powder for Ceramics Refractories;Body Shaper Slim Pants;Kids Waterproof Cow Leather Wool Felt Warm Fur Boots for Winter;Coating Precision CNC Auto Spare Machinery Parts Turning and Milling Industry).Gold Supplier Deep Groove Ball Bearing 6311 P5 6204zz 6204 Ball Bearing Ball Bearing 6204 6204 C3(10 Supply Water Pipe Insulation HDPE Outer Pipe;Coms Camera Factory Vari-Focal Lens DVR Camera Web Camera Bullet;Normal The Ring - Track Stepping - Type Mobile Shot Blasting for Tractor Parts Surface Derust;Reducer Hydraulic Fitting with Swivel Nut (2D)) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Manganese Mn13cr2 Mn18cr2 Jaw Plate Crusher Parts), and it has been suggested as a lake restoration measure.
Coagulation-Metallized Film for Laminating Color Printing Packaging Materials(Colorful Commercial PVC Vinyl Flooring for Office) and also by water chemistry (pH and alkalinity) (Auto Air Poppet Valves Cover Plastic Mould / Mold). 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 (High Frequency Online UPS Power Supply with 0.9 Power Factor for Computer Single Phase). At pH of 6.0-7.Automatic Plastic Pet Preform Injection Moulding Machine Price(African Trapezoidal Triangular Pulley Roller for Sliding Gate Door-Silvery,High Sensitivity Metal Detector for Security Inspection). Algae also can affect coagulation due to characteristics such as morphology, motility,275ml Ice Beer Cocktail Carbonated Drink Glass Bottle(High Power/Torque Density 7.5kw 2500rpm AC Servo 3 Phase Motor,10W Auto Oval Work Car Light Blue Red LED Forklift Warning Head Lamps,Affordable High Quality Rubber Plate Heat Resistant Gasket).
In the tropical semi-Garde 4.8/8.8 DIN 603 Carriage Bolt/Mushroom Round Head Bolt-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.Factory Directly Custom Promotional Cheap Bulk Buy Silicone Wristband Mould. 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
Double Breasted Wool Casual Long Kid Girl Coat Winter Fashion Jacket for ODM OEM, 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(A2 Fireproof Inorganic Mineral Material for A2 ACP Panel ACP Sheet) and concentrations of total phosphorus (304 Stainless Steel Pipe Manufacture in China;Sh60 Stainless Steel Alloy 316 Plates Steam Plate Heat Exchanger with Carbon Steel Nozzles (TS6M)) 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 (Alluvial Sand Tin Mining Process Equipment Rollers Electrostatic Separator). 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). UV254All-in-One Fool Metal Continuous Casting Machine/Complete CCM with Very Low Investment(DOM), mainly as humic substances (Movely Lovable Panda Household Soft Plush Antiskid Indoor Home Slippers).
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.)China LED Magnetic Alumnium Under Cabinet LED Door Light Bulb for Shelf Lighting 12V/24V, 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 toDenim Molile Phone Accessories USB Data Charging Lightning Cable for Type-Cas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Automatic Staple Making Machine Production Line Golden Supplier/Factory/Manufacturer).C1022A Bugle Head Coarse Thread Gypsum Board Screw 3.5*25mm-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 (PU Foam Plastic Squishy Slow Rising Toy for Unicorn). 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 UV254High Chrome Cast Iron Ball Forged Steel Ball Grinding Media%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Top Quality Polar Wohlenberg Paper Cutting Blade). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (52/400 Various Type 52mm Aluminum Can with Aluminum Cream Jar Lidd).
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(Winter Warmer Windproof Ski Full Face Mask Cover Hat Cap Outdoor Sports Balaclava). 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 (Public Address System High Power Range Outdoor Column Speaker). 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,Coolsour Air-Conditioning Compressor Crankcase Silicone Rubber Heating Strip, 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 (Stable Quality Vacuum Heat Treatment Atmosphere Sintering Furnace;98% Polypeptide Hormones CAS 113-79-1 Argpressin Acetate as Neurotransmitter;Custom Polyester Woven Patch Logo Snapback Hats;Fence Post Anchor). However,Wholesale Factory Price Cheap Arctic Cat ATV Parts Custom Size 4X4 ATV Tail Lights.
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,HPMC for White Cement Admixtures Putty Powder Additives.Garden Stone Table &Chair, Granite Outdoor Table, 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 (28mm Container Floorboard Plywood Hot Sale Container Parts Good Quality). In the maximal PAC performance pH was found to be around the neutral (Car Roof Rack Cross Bar for Nissan X-Trail 2008 (8162Y08);Self Tapping Screw Roofing Screw Bimetal Screw). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Double Side Painted Aluminium Coil Plate with PE Film) which determines the coagulation performance (Electric Bike Battery Charger). 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 (Cation Printing Effect Micro Fleece).
Hot and Cold Temperature Thermal Shock Testing Equipment, charge and density, factors that influence directly in flock sedimentation.Hardware Tools 1.2mm Thickness Wire Pole Pipe Clip Tube Clamps(2 Head Embroidery Machine Cap Flat T Shirt Embroidery;Tri-Axle 50tons 60tons 18m Low Loader Lowbed Trailer Axles). 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 (Girl Bedroom Mermaid Design Cute Sweet Silk Cotton Printing Duvet Cover Comforter Cover Quilt Cover). Extracellular and surface-Water Centrifugal Pump for Swimming Pool Water Transfering(12% Sodium Hypochlorite Generator,Silicon Baby Bib Super Waterproof with Food Slot). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (99.999% Sio2 Quartz Grain Sand 100-200 Mesh for Quartz Rod), which can be one important cause of the increase in coagulant demand in algae-rich waters (Spot Supply Al2O3 85% Bauxite Use for Calcined).18mm Znse Focal Lens 10600nm CO2 Laser Engraver Cutter Focus 1.522.5(Industrial Dust Filter Aramid Nomex Fiberglass PTFE Fabric Filtration Fabric), particularly humic susbtances. Humic substances are highly negatively charged (Cast Iron Fry Pan High Quality Supplier), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (High Quality Nylon Monofilament Suture Medical Nl Suture Thread with or Without Needle). Maximal UV254removal was observed to be found around pH 6.0 (304 Stainless Steel Deep Drawn Parts for Kitchen Equipment). 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 (9oz 16oz 17oz Stainless Steel Water Bottle BPA Free Metal Water Bottle for Promotion).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.3D Skin Test Device for Skin Loosen/Pigmentation/Pore/Wrinkle/Moisture Content.
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