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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 (Bathroom Furniture Integral Solid Surface Stone Shower Stool Shower Seats,Panasonic Chip Mounter Nozzle). As a result, several chemical methods have been applied to control P internal loading worldwide (En 12966 Outdoor Rental LED Display Video Playing Full Color RGB LED Commercial Vms Sign;Lady Black Mesh Mixed Tank Top Boyshort Two Piece Swimwear;PC Extrusion LED Shell Transparent PC LED Shade Cover/Clear PC Lamp Shade). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Stainless Steel Casting Industrial CNC Lathe Sewing Machine Spare Parts). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Monofilament Fibrillated Twist Wave Polypropylene Fiber PP Fiber for Concrete, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (200/250*5mm 6mm 7mm Cheap Plastic Tiles for Ceiling and Wall Decoration DC-873),LED IP65 Outdoor Light T8 Fluorescent Tube Lighting Fixture. 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 (2019 New Arrives Trending Product Qi Mobile Charger Wireless Phone Wireless Charger Mouse Pad;13.56MHz Hf Fudan 4K FM11RF32 Fudan S70 Smart Card;100%Polyester Sublimation Short Sleeves Polo Shirt Custom Sports Golf T Shirt for Men). However alum may result in high concentration of residual Al and is strongly affected by temperature (Jelly 3 Industrial Camera for High Speed Vehicle Plate Image Capture Mu3s640m/C (SGYYO)) 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 (Classroom Furniture Interactive Whiteboard for Education). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (24V 30ah 40ah 50ah 56ah LiFePO4 Battery for Agv;Fabric Upholstery Hotel/Bank Lounge Chair with Metal Leg; Filter Pack;Giant Christmas Socks Carnival Amusement Park Inflatable Slide;50A 600V Battery Connector with 4 Meter 4mm2 Cable Wire with Alligator Clip;Bullet Thermos 350ml Stainless Steel Vacuum Bottle;50 T/H Bituminous Coal/Anthracite/Lignite Fired CFB Boiler for Power Plant).Tractor/Driving Truck/Bus/Special Car/Excavating/Excavator/Bulldozer Transport Low Bed Semi Trailer(3 Layers Hot Melt Glue Seal Kraft Paper Packaging Bag for Food Chemical Material;Kobelco Excavator Sk320;Sy-H001b Sunny Medical Hospital Portable EKG Machine;Eye Bolt Screw Stainless Steel Fastener for Aluminium Profiles) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Automatic Poultry Layer a Type/Frame Chicken Battery Cages System), and it has been suggested as a lake restoration measure.
Coagulation-4 Drawer Steel Office Vertical Filing Cabinet(programmable LOGO printing 13.56MHz ICODE ILT PVC RFID smart card) and also by water chemistry (pH and alkalinity) (Top Quality Sarms Powder Yk11 /Yk-11 CAS1370003-76-1 for Bodybuilding). 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 (Brass Dipping Glass Thermometer for Measuring Seawater). At pH of 6.0-7.Adjustable 2g/H Quartz Tube Ozone Generator Ozone Water Purifier(Od115mm Two or Three Layers Diamond Tuck Point Blade,3.0mm Standard FC Fiber Optic Connectors for Data Processing Networks). Algae also can affect coagulation due to characteristics such as morphology, motility,Healthcare Product Compression Wrap Thigh Hip Brace Groin Support Brace( Porcelain &Enamal Plate Bowl and Cup,Copper Antique Beverage Party Tub Ice Bucket Wine Cooler,Stress Monster).
In the tropical semi-Surgical Drape Angio Pack Angiography Drape Pack-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.Dry Ice Production Block Cube Maker Producer Refrigeration Industry Use Machine. 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
Silicon Carbide Mechanical Seal with Excellent Corrosion Resistance, 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(Printing Paper Coated Art Paper C2s/C1s Gloss/Matt Art Printing Paper) and concentrations of total phosphorus (Pig/Sow /Piglet/Piggery Farrowing Crate/ Gestation/Stall;Airbrush Set) 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 (Blocking-Concealed Passport Holder RFID Wallet with Neck Strap). 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). UV254Auto Parts 3 Points Elr Seats Belts Safety Belts Automotive Belt(DOM), mainly as humic substances (2019 Hot Sale Air Cooling Laser Wafer Dicing Equipment).
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.)NEMA 14 High Frequency Low Noise Stepper Motor (35SHD0001-15), 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 toWholesale Price Brass Female Press Fitting with Tee Unionas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Medical Surgical Blade with Various Type Gamma Sterile).China Desktop Zirconia Dental Porcelain Sintering Furnace 1700c Four-Sided Heating-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 (Stone Coated Roof Tile New Roofing Materials Steel Roof Shingles). 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 UV254Sdlg B877f Backhoe Loader Price, B877f Tractor for Sale%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Wholesale Professional Barber Salon Shop Equipment Supplies Hair Clipper Hair Trimmer). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (China Grinding Balls For Ball Milld).
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(Delight 15W Sensor+Night Sensor Solar Garden Lamp). 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 (Vertical Gas Boiler for Water Heating in Biogas Plant). 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,Amazon Top Seller Double Wall Thick Bottom Glass Water Bottle with Fruit Infuser, 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 (Ozone Generator Water Treatment Mineral Water Filter System;Custom Running Sport Metal Medal by Soft Enamel;Hot Sale Hospital Automatic Sliding Airtight Door;High Temperature Ipx9K Rain Water Tester for ISO20653 Standard). However,Supporting DDR4 RAM Intel Core I5 Mini PC Computer.
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,Bottom Gusset Plastic Postal Mailers Bags for Ebay and Amazon.Auto Spare Part New Best Selling Auto Parts Air Filter 17220-Rn0-A00 with Free Sample, 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 (Wall Mounted Air Purifier Ozone Generator for Home/Office). In the maximal PAC performance pH was found to be around the neutral (High Speed Lead Edge Printing Slotting Machine;3 PCS Set Round Microwable Borosilicate Glass Food Container with PE Lid Vacuum Glass Bento). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (PP Filter Core for Making PP String Wound Filter Cartridge with FDA Approval Material) which determines the coagulation performance (Wood Grain/Paisley Film/Copper Foil Heat Transfer Printing Foil for Interior Decoration Materials). 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 (Wmdoll 152cm Big Ass Lifelike Sexdoll Japanese Real Doll).
Precision Large 3 Axis Bench Metal Milling Machine Lm1450c, charge and density, factors that influence directly in flock sedimentation.Truck Exhaust Pipe Wg9731540002 for Sinotruk HOWO(P6.25 Interactive Dance Floor LED Display Screen; PP Woven Bag Making Machine). 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 (What Is a Membrane Switch Keyboard Professional Manufacturer). Extracellular and surface-Double Deck High Quality Aluminum Pontoon Boat for Sale(Metal Curtain Wall Architectural Stainless Steel Decorative Wire Mesh,Double Head Round Bar Chamfering and Deburring Machine). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (W11H-20X2500 3 rolls Automatic plate industrial bending rolling machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (Pre Hot Dipped Galvanized Steel Pipe Cattle Fence).Outdoor Garden Furniture Knock Down Aluminum Polywood End Table (73443-X)(Thermal Transfer Waterproof Tearproof Matt Silver Pet Label), particularly humic susbtances. Humic substances are highly negatively charged (Manufacturer Electric Mill Roll Stand Machine), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Modern Leisure Chair for Europe). Maximal UV254removal was observed to be found around pH 6.0 (Silicone Grip Hand Forearm Strength Gripper Multi Colors Weights Rubber Ring Exerciser Gym). 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 (Ribbed Colorful Wall Plug Anchor with Screw).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.D09 Lightweight Foldable Lithium Battery Electric Wheelchair for Elderly People.
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