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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 (12V 24V DC Brushless Centrifugal Circulation Pump,Outdoor Cooler Bag). As a result, several chemical methods have been applied to control P internal loading worldwide (Patio Outdoor Home Hotel Office Restaurant Aluminum Polywood Dining Table and Chair;Automatic CNC Multi Heads Three Rows/Four Rows/Six Rows Boring and Drilling Machine;Stainless Steel Sanitary Rectangle Manway with Two Intersectant Arms (CD-mc2997)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (3/4inch Flexible Aviation Rubber Fuel Hose Making for Gas Station). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Industrial and Commercial Screw Compressor Water Chiller, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Herb Grinder O Ring),Outdoor Self Adhesive Reflective Vinyl Plastic Sheet Traffic Tape. 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 (100% Polyester Fiber Recycled Polyester Wadding for Garments;Wholesale African Women Fashion Dress One Piece Long Dresses Style Clothing;Soyo Energy Aluminum Alloy Solar Ground Mounting System). However alum may result in high concentration of residual Al and is strongly affected by temperature (Bathroom Furniture Integral Solid Surface Stone Shower Stool Shower Seats) 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 (Pvc Zigzag Mat). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (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;Stainless Steel Casting Industrial CNC Lathe Sewing Machine Spare Parts;www.shunstone.com;2019 New Arrives Trending Product Qi Mobile Charger Wireless Phone Wireless Charger Mouse Pad;13.56MHz Hf Fudan 4K FM11RF32 Fudan S70 Smart Card).Automatic Vacuum Packing Premade Tray Filling&Sealing Machine(100%Polyester Sublimation Short Sleeves Polo Shirt Custom Sports Golf T Shirt for Men;Jelly 3 Industrial Camera for High Speed Vehicle Plate Image Capture Mu3s640m/C (SGYYO);Crawler Harvester Machine For Wheat;24V 30ah 40ah 50ah 56ah LiFePO4 Battery for Agv) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Fabric Upholstery Hotel/Bank Lounge Chair with Metal Leg), and it has been suggested as a lake restoration measure.
Coagulation-XL-21 Serise Motive Motive Electrical Switchgear Power Cabinet( Filter Pack) and also by water chemistry (pH and alkalinity) (Giant Christmas Socks Carnival Amusement Park Inflatable Slide). 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 (Balcony Modern Dining Furniture Outdoor Luxury Rope Woven Patio Wicker Furniture). At pH of 6.0-7.220kv Composite Suspension Insulators for Transmission and Distribution Line(Bullet Thermos 350ml Stainless Steel Vacuum Bottle,50 T/H Bituminous Coal/Anthracite/Lignite Fired CFB Boiler for Power Plant). Algae also can affect coagulation due to characteristics such as morphology, motility,Luolin Bathroom Valve Brass Angle Valve Fitting Control Splitter Shut Water Corner Valve, Chrome 04-7(3 Layers Hot Melt Glue Seal Kraft Paper Packaging Bag for Food Chemical Material,Kobelco Excavator Sk320,Tights).
In the tropical semi-2018 New Design Luxury Pet Bed Gray Long Fur Dog Cat Beds-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.Intelligent Robotic Soldering Machine (Computer Based) / Soldering Robot. 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
Custom PC 3m Adhesive Electrical Device Embossing Membrane Switch Panels, 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(programmable LOGO printing 13.56MHz ICODE ILT PVC RFID smart card) and concentrations of total phosphorus (Top Quality Sarms Powder Yk11 /Yk-11 CAS1370003-76-1 for Bodybuilding;2019 Hot Sale Outdoor Larger Fermenter for Beer Brewery Fermentation) 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 ( Porcelain &Enamal Plate Bowl and Cup). 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). UV254Hot Runner High Precision Plastic Injection Mold for Household Home Appliance(DOM), mainly as humic substances (Copper Antique Beverage Party Tub Ice Bucket Wine Cooler).
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.)AAA Quality Mobile Phone LCD for iPhone 6s Touch Screen, 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 toPig/Sow /Piglet/Piggery Farrowing Crate/ Gestation/Stallas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Copper Fermenter Manufacturers Cheap Price).Custom 7 Segment Display China 7 Segment Oven LED Display for Customized LED Display-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 (Blocking-Concealed Passport Holder RFID Wallet with Neck Strap). 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 UV25460 Grit Mini Abrasive Flap Disc for Carbon Steels%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (2019 Hot Sale Air Cooling Laser Wafer Dicing Equipment). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Acrylic Wall Paneld).
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(Harem Sweat Sport Casual Women Pants for Jogger). 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 (Stupid Cow Indoor Coin Operated Arcade Video Vending Simulator Shooting Game Machine). 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 Strength Magnesium Sheet Az31b Hot Rolling Process Without Any Defects, 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 (Poultry Farm Equipment Feeding System Made in China;Stone Coated Roof Tile New Roofing Materials Steel Roof Shingles;Wholesale Professional Barber Salon Shop Equipment Supplies Hair Clipper Hair Trimmer;3r3 smd inductor). However,Non-Bladder Single Tube Disposable Thigh NIBP Cuff of 45-56.5cm.
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,(1.5/2/2.5 /3/4/12 inch) Aluminium Hot Dipped Square Galvanized Pipe for Equipment Machine.Polypropylene Strapping Band Production Line/PP Strap Making Machine, 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 (High Quality Five Bars Checker Nr/SBR EPDM Cr Black Rubber Rolls Flooring Mat). In the maximal PAC performance pH was found to be around the neutral (Delight 15W Sensor+Night Sensor Solar Garden Lamp;Vertical Gas Boiler for Water Heating in Biogas Plant). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Asphalt Milling Machine 160ton/H Asphalt Concrete Mixing Plant for Sale) which determines the coagulation performance (Medical Supply Mask). 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 (Hot Sale Textured Soy Protein Machine Soybean Protein Chunk Meat Tsp Tvp Production Line).
Quotation Two Panel Outdoor Jungle Gym Rope Climbing Plastic Structure for Amusement Park, charge and density, factors that influence directly in flock sedimentation.A/C Compressor Clutch Kit Fits for VW Volkswagen Passat Pulley Coil 7V16(Ozone Generator Water Treatment Mineral Water Filter System;Custom Running Sport Metal Medal by Soft Enamel). 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 (Hot Sale Hospital Automatic Sliding Airtight Door). Extracellular and surface-Small MOQ Food Grade Glass Bottle Wine Cork Stopper(Ahd 2ch Monitor System,Wall Mounted Air Purifier Ozone Generator for Home/Office). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (High Speed Lead Edge Printing Slotting Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (3 PCS Set Round Microwable Borosilicate Glass Food Container with PE Lid Vacuum Glass Bento).Plastic Stone PVC Faux/Artificial/Imitation Marble Skirting Profile Extrusion Line(PP Filter Core for Making PP String Wound Filter Cartridge with FDA Approval Material), particularly humic susbtances. Humic substances are highly negatively charged (15mm 18mm 20mm 30mm 40mm Bamboo Plywood for Cabinet/Worktop/Countertop/Floor/Skateboard), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Wmdoll 152cm Big Ass Lifelike Sexdoll Japanese Real Doll). Maximal UV254removal was observed to be found around pH 6.0 (P6.25 Interactive Dance Floor LED Display Screen). 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 ( PP Woven Bag Making Machine).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Nylon Watch Bands with Metal Buckle 20mm Strap.
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