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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 (4 Fibers Wall-Mounted FTTH Distribution Box,Sheep And Goat Fence Panels). As a result, several chemical methods have been applied to control P internal loading worldwide (80kw Electric Canopy Diesel Generator Powered by Cummins with Ce/ISO;Vehicle Wheel Anti-High Temperature Zirconia Ceramic Seal Pump Impeller;Water Park Outdoor Playground with Water Spray Device for Sale). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Customized Logo Low Price Fashion Wholesale PVC Silicone Wristband for Merry Christmas Gift). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Outdoor Full Color P6mm Front Maintenance LED Display, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Advertising Banner Flags),Sachet Sauce Packing Machinery for Honey Stick. 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 (1/2 Inch Brass Stem Handwheel Gate Globe Valve;Commercial Coffee Roasters for Sale 1kg 3kg 6kg 12kg 120kg Coffee Roaster Machine Manufacturer;Perforated Decorative Aluminum Metal Curtain Wall Single Panel Sheet for Curtain Wall Decoration). However alum may result in high concentration of residual Al and is strongly affected by temperature (Waste Pet Plastic Bottle Crushing Washing Recycling Machine) 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 (Sinter Metallurgy Part in in Customer′s OEM Design). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Glass Mike Bottle 200ml 250ml with Screw Cap Straws;Liquid Laundry Detergent Small Single Bag Packing Machinery;2019 Shenzhen CNC Machining Companies CNC Small Aluminum Part;Cee/IEC 32A 5p 400V 3 Phase European Standard Plug;China Perforated Mesh;Semi-Automatic Hydraulic Leather Football Machine;15 Inch IP65 Waterproof Industrial Touch Screen Monitor).SPD Belt Conveyor Idler Frame, Roller Frame, Through Idler Frame(Modern Style Prefabricated Steel Structure Poultry House; Splicing Machine S6;6 Inch Wheel;Double Deck High Quality Aluminum Pontoon Boat for Sale) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Skin Cool Cold Hot Hammer Electroporation Machine for Facial Lifting (VS-885)), and it has been suggested as a lake restoration measure.
Coagulation-OEM High Quality Stainless Steel Ladies Anolog Wrist Watch Jewelry Diamond Watch 71092(Customization Industrial Steam Boiler Repair Parts Steam Economizer Boiler Pipes) and also by water chemistry (pH and alkalinity) (Floor Mounted Glass U Clamp Channel for Glass Balustrade). 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 (API J55 Steel Btc Thread Casing Coupling Manufacture). At pH of 6.0-7.3/8 CRV Industrial High Quality Quick Release Ratchet Handle Wrench(High Quality Curve Spear Tunnel Bolt for Concrete Ring,Brand New Forklift with Double Front pneumatic Tire). Algae also can affect coagulation due to characteristics such as morphology, motility,Aluminum/Aluminium Sliding Doors Philippines Price and Design System(Automatic Small Round Bottle Water Washing Filling Capping Machine,MP24ga5 DC12V Micro Motor Step Stepper Stepping Motor for Air Conditioner Vibration,Competive Price 1.8mm-8mm Rectangle/ Oval Lighting LED Wall Mirror for Home Decoration).
In the tropical semi-High Quality Double Link Ra DVI D 24+1 Pin Connector-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.Seu 2*8 AWG Concentric Service Entrance Cable. 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
Healong Company Customized Soccer Jersey for Club, 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(White/Gray Colors U-PVC Water Supply Pipe for Plumbing System) and concentrations of total phosphorus (Hot Sales Good Softness Red PE Protective Film Surface Protection for Color Steel Plate;Anti Dust Mask Zipper) 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 (Organic Bride Nylon Cosmetic Makeup Travel Bag Pencil 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). UV254Top Quality Abrasion-Resistant PVC Artificial Leather for Bedroom Furniture(DOM), mainly as humic substances (High/Middle/Low Back Office Chair / Executive Computer Chair / Ergonomic Mesh Office Chair).
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.)50 Bend PVC Pipe/Belling PVC Pipe/Making Machine, 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 toSmall Camping Inflatable Roof Tent with Strutas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(12mm Marine Plywood Manufacturers Cheap Price).50 T/H Bituminous Coal/Anthracite/Lignite Fired CFB Boiler for Power Plant-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 (Hot Sale 3 Players Mini Amusement Carousel Horses Rides Carousel Merry Go Round Kiddie Ride). 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 UV254Factory Flint Lighter Disposable Cheap Chinese Lighter Plastic Lighter%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Esavior 30W All in One Solar LED Light Street Light Motion Sensor Energy Saving Outdoor Light). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Lotus Root Flour Making Machined).
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( Grass Cutting 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 (Honglang New Wood Burning Stove Fan of 4 Blades (HL-800C1)). 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,High Speed Wheel Hub Bearing/Automotive Wheel Bearing Units/Wheel Bearing, 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 (ANSI B16.5 Stainless Steel SS316 Forging Blind Flange;Sintered Rare Earth NdFeB Magnetic Permanent Neodymium Block Magnet for Motor;Professionally Made Aluminum Magnesium Die Casting Die;Medical Part Plastic Moulding). However,PVC Plank /Spc Click/ Popular PVC Flooring/DIY Flooring/Building Material/Vinyl Floor/Tile/Plank.
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,Automatic Mango Juicer Filling Machine / Canned Juice Production Line.Modern 60W Glass Table Lamp for Office Bedroom Home Decor, 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 (Auto Spare Parts Aluminum Air Suspension Lowering Springs Coilover). In the maximal PAC performance pH was found to be around the neutral (Interior Decorative Soundproof Acoustic Foam Sponge Panel (AFSYF50-5);China Cup Set Handmade Coffee Cup and Saucer Set). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (NEMA IP65 Wall Mount Electric Metal Cabinets) which determines the coagulation performance (Car Garage Use Mini Induction Heater for Bolt and Nut Heating). 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 (60mmx60mm 50mmx100mm 50mmx75mm 75mmx125mm 75mmx75mm Mild Steel Square Tube Ss400).
China Qingdao Factory Interlocking PVC Garage Floor, charge and density, factors that influence directly in flock sedimentation.Waterproof Carbon Fiber Hard EVA Case for 3D VR(Ceramic Floor Tile Wear Resistant Tile Non-Slip Floor Tile;Hight Quantity Micropore Tfc-3012-300gpd RO Membrane). 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 (4*0.22mm2 Core Unshielded Fire Alarm Cable 18awg). Extracellular and surface-100% Leak Proof, Auto Seal Stainless Steel Travel Mug Cup (SH-SC36)(Hot Sale DIN603 Carriage Bolt China Manufacture Fastener,Strong BOPP Laminated 25kg 50kg Rice Polypropylene Sack). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation ( CNC Milling Machine (VMC850)), which can be one important cause of the increase in coagulant demand in algae-rich waters (20W 18V Low Price PV Module System Power Supply DC USB Charger Monocrystalline Solar Panel Ce FCC).Rubber Recycling Machine Powder Tire Derived Fuel Machine Small Tyre Recycling Plants(Horizontal Double Ribbon Mixer Machine for Mixing Dry Powder), particularly humic susbtances. Humic substances are highly negatively charged (Luxury Black Color Stainless Steel Shower Enclosure (MB-204)), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Black Acrylic Steam Shower Room Cabin with 6mm Tempered Glass). Maximal UV254removal was observed to be found around pH 6.0 (860-960MHz Rfif UHF Price Label for Jewelry Programmable RFID Tag). 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 (Jiusheng Brand Wj-3cbm Diesel Engine LHD for Mining Conveyor).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Cheap Customized PVC Rubber Book Mark Clips with Any Logo Design for Promotion/Advertising (XF-BM10-).
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