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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 (China Gingseng Extract Ginsenosides 15% 20% 80%,Digital Shelf Label). As a result, several chemical methods have been applied to control P internal loading worldwide (PVC Shoe Upper with LED Light for Kids Slide-on Slippers;Plastic PVC Car Mat Making Line / PVC Coil Carpet Car Seat Cutting Machine;Duct Outdoor Single-Mode Gyfy Fiber Optic Cable). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Handrail Fitting / Stainless Steel Round & Square Tube Connector). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Easy Maintenance Automatic 6000PCS/H Egg Tray Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Paint Tin Cans),Used Jam/Tomato/Chilli Pasty Manual Filling Machine with Sauce Material. 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 (Kitchen Stainless Steel Washing /Wash Double Bowl White Sink;Factory Price 50W LED Corn Bulb E26/E39/E27/E40 Base Indoor and Outdoor Industial Lighting;FRP Insulated PU Foam Composite Panel for Refrigerated Truck Body). However alum may result in high concentration of residual Al and is strongly affected by temperature (Whole-Sale 25cm Cleanroom M3 Wipes Cleaning Tissue Cellulose Wipers) 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 (Shipping Container House Builders). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (1325/1530/2030/2040 CNC Woodworking Router Machine with Cheapest Price and Big Discount Is on Big Sale;Wholesale Portable Travel Bamboo Tooth Brush Holder;Wholesale Brosilicate Glass Smoking with Black Triple Layer /Triple Arm Straight Glass Water Pipe;Stationary Asphalt Mixing Plant From 100tph to 400tph;Electric Lighting Wiring Connector & Crimp Ring Terminal Open Barrel Terminals (HS-DZ-0094);V9 37kw 220V 380V Various Motor Type Control Flexible and Adaptable AC Drive;Automatic Non-Woven T-Shirt Bag Making Machine with High Efficient).Korea Glittery Heat Transfer Film /Vinyl for Clothes/T-Shirt Printing Cdg-16 Light Multi(Belt Driven Oil Lubricate H-Pump Reciprocating Two-Stage Piston Air Compressor (RT1.5/12.5); Non-Contact Thermometer Gt750;All Gears Metal Steel Gap Bed Advantages Lathe Machine for Sale (CHB6250 );Personal Skin Care Silicone Sonic Facial Cleansing Brush) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (UV Coating Surface Treatment and Indoor Usage Plastic PVC/WPC/Spc Flooring Extruder Machine), and it has been suggested as a lake restoration measure.
Coagulation-Glossy Silvery Anodized Aluminium Profile for Windows and Doors(Hot DIP Galvanized Scaffolding Hook-on Ladder Ringlock Scaffolding with Hooks (RML)) and also by water chemistry (pH and alkalinity) (Customized Thread Cutter of M105*3.0 Large Cutting Tools for CNC Machine Tools). 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 (China Clear Laminated Glass). At pH of 6.0-7.Shoebox Canopy Lamp 60W LED Light Evergy Saving 2835 Chips Corn Bulb(ASTM A53 Black Round Metal Carbon ERW Steel Pipe,Motorcycle Parts Motorcycle Brake Caliper and Brake Master Cylinder for Wave110). Algae also can affect coagulation due to characteristics such as morphology, motility,Electronic 4-20mA 0-5V 0-10V Pressure Sensor Switch with on/off PNP/NPN Switching(Alumina Ceramic Foam Filter for Aluminum Casting,Two Sides Grey Silicon Coated Fiberglass Waterproof Roofing Fabric Cloth,Anti-Vandal and Waterproof Pushbutton Switches).
In the tropical semi-Best Quality Plastic Wall Plug Expansion Anchor-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.Cast Iron Casserole Pot Roaster with Cover 7L Oval Dutch Oven. 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
Automatic Disposable Hotel Supplies Packing Machine Horiaontal Wrapping Machine, 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(Quick Drying Waterproof Silicone Sealant Construction Adhesive Glue for Glass) and concentrations of total phosphorus (12mm LED RGB String Light/ LED Pixel with SD Card Controller;Customerized OEM Matel Stamping Weld Agricultural Machinery Parts Harvester Parts) 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 (Manufacturers Wholesale Microfiber Car Cleaning Towel). 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). UV254Good Quality UPS Batteries 12V 65ah for Burglary Protection System(DOM), mainly as humic substances (High Precision Machinery Plastic Parts with Injection Mold).
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.)Bh36/Dh36/Ah36 Hot Rolled Marine Steel Shipbuilding Plate, 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 toAuto Styling Car Interior Accessories Central Armrest Storage Glove Trau Box for Rangeras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(200 Amp Plasma Cutter).Portable Marking Machine Table for Height Adjustment-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 (Professional Manufacturer Large IR Touch Screen Monitor 32 43 55 65 Inch for Commercial Kiosk). 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 UV254Hovenia Dulcis Extract Dihydromyricetin (DHM) 1%-20%%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Heavy Duty Double Ladder Trailer Top Tent). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (11.8Lovely Pink Rabbit Children′s Backpack Bos-1235/30cmd).
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(99% Nano Grade Electronic Use Titanium Dioxide). 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 (18mm Znse Focal Lens 10600nm CO2 Laser Engraver Cutter Focus 1.522.5). 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,Best Quality Popular Lovely Washable Pet Accessories Luxury Soft Dog Bed, 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 (12V DC Vehicle Charger Superior Suction Cup Auto Car Electric Fan;Water Oil Liquid Level Measurement Devices Glass Level Gauge;OEM Agricultural Combine Painted Conveyor Driving Chain Sprocket;m.gmcmagnet.com). However,AC Magnetic Contactorstc-40 (GMC) Electric Contactor.
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,Large Outdoor Water Park Slide/Water Turntable Amusement Equipment.CPVC Pipe Extrusion Line/PVC Pipe Production Line, 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 (0.5-1.5mm Broken Silica Gel with 35% Moisture Absorption in 25kg Bulk Bag). In the maximal PAC performance pH was found to be around the neutral (Resealable Ziplock Round Bottom Biodegradable Food Packaging Pouch Wholesale in China;Best 1.75mm 3mm ABS PLA 3D Printer Filament Supplier 1kg 5kg for 3D Printing Clear ABS Filament). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Manual Brass Button Time Delay Auto Stop Urinal Flush Valve (C-16)) which determines the coagulation performance (Quality Die Casting Aluminum for Light Cup / Heat Sink /Lighting Housing with SGS). 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 (High Heat Resistant Silicone O Ring for Thermos/Bottle/Glass Jar).
Stainless Steel Tube Mill for Decorative, Construction Pipes Price, charge and density, factors that influence directly in flock sedimentation.Energy Saving One Step Automatic Tritan Pet Blow Molding Machine(Bzw-20ts Servo Large Terminal Crimping Machine;Hot Sell Peptides Follistatin 315 Price--Factory Direct Supply 99% Purity). 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 (Car Cooling Spare Parts Compressor Magnetic Clutch). Extracellular and surface-Commercial Automatic Ultrafine Air Jet Mill for Sale(C855hdx C855kcsb C87bf K1ls-2244-2869 C100 24.43sb Scarifier Blade Tools,Jingsun High Efficiency 380W 400W Perc Mono Solar Panel). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (2 in 1 Baby Feeding Chair Kids Eating High Chair), which can be one important cause of the increase in coagulant demand in algae-rich waters (250W /500W/750W/1000W Big Power Fat Tire Electric Mountain Bike/Snow Bike/Electric).Carnival Rides Samba Balloon Race Happy Swing Jellyfish for Sale(Linear Position Magnetic Position/Motion Sensor 150mm), particularly humic susbtances. Humic substances are highly negatively charged (Stainless Steel Non Return Swing Single Disc Wafer Check Valve), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Support TF Card / Bluetooth / WiFi / LAN 2GB + 32GB 7 Inch Pipo X8 PRO TV Box Style Mini PC). Maximal UV254removal was observed to be found around pH 6.0 (Flexional Soft Head Electronic Digital Thermometer). 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 (Cal117 (TB117) Flame Retardant Fire Barrier Batting Felt).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.3 in 1 Flat Noodles Data Transfer Charger Cable for Android/Ios.
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