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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 (Online Shop China White Sticky Painter Felt Roll,Moving Die Rheometer). As a result, several chemical methods have been applied to control P internal loading worldwide (Alumina;Outdoor Basket Hanging Chair Balcony Chair Rattan Swing;Handle Adjustable Magic High Quality Microfiber Magnet Mop for Home Cleaning 1045). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Cheap Factory Custom A4 PP Size Clear File Folder Document Holder Stationery Bag File Folder). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,MP24ga5 DC12V Micro Motor Step Stepper Stepping Motor for Air Conditioner Vibration, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Fuel Pumps Plunger Pump Precision Lapping Polishing Machine Surface Finishing),Sf606 Serve Motor Automatic Wood Cut off Saw Machine. 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 (Hot Selling Waterproof Anti-Slip Vinyl PVC Homogeneous Plastic Roll Floor;Wallbox EV Charging Station with Ce Approvals;Square Home Sofa Throw Decorative Pillow Case Cushion Cover). However alum may result in high concentration of residual Al and is strongly affected by temperature (Indoor FTTH 96 Cores Distribution Loose Tube LSZH Fiber Optic Cable) 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 (Private Label Amazon Hot Sale High Quality Nature Hyaluronic Acid Serum for Face). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (CNC Deep Machining Aluminium TV Frame Part with Anodization Surface;50ml 150ml 500ml Glass Aroma Diffuser Bottle;Manufacturer New Design Reusable Clear Lalique Glass Perfume Packaging Bottle;Ductile Iron Service Gate Valve Ductile Iron Screwed Ends Resilient Gate Valve Thread;Roll Up Rapid Door Factory & Manufacturer;New Arrivals Soccer Synthetic Grass;380W New Beam Moving Head Night Club Disco Lighting for DMX Controller).Power Transformer Voltage Transformer Pq2620 Series High Frequency Transformer(Large Diameter ASTM A213 TP304L Seamless Stainless Steel Pipe;Trisun Mechanical Seal Spare Parts Wave Spring;PE Film Tray Shrinking Wrapping Shrink Packing Machine;Manufacturer Price High Strenghth HDPE Garbage Bag) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Jmc Vacuum Road Dust Truck Mounted Sweeper Car), and it has been suggested as a lake restoration measure.
Coagulation-Education Supply School Gifts Craft POM POM Child Toy Educational Equipment (P4097)(for Steel Arc Furnace Use The Quality Should Be Good Certified Grades) and also by water chemistry (pH and alkalinity) (Hairise Har8505 Heat Resistant Modular Conveyor Belt with Food Grade). 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 (Merry Go Carousel Ride 6 Seats Amusement Park Ride). At pH of 6.0-7.Fashion in China Tag Watches Men Quartz Water Resistant Stainless Steel Back Dw Watches( Aluminum Parts,Thermal Insulation Rubber Foam Pipe for Air Conditioning). Algae also can affect coagulation due to characteristics such as morphology, motility,Thickness 140 Micron Pharmaceutical Cold Forming Blister Aluminum Foil(Food Grade Composite Packaging Standup Plastic Pouches Bag with Zipper,Waterproof Realistic Dildo G Spot Vibrator Adult Sex Toys,German Technology Waterproof Click PVC Vinyl Flooring).
In the tropical semi-13.56MHz Hf Fudan 4K FM11RF32 Fudan S70 Smart Card-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.ASME/ANSI B16.9 Stainless Steel Sch40/80 Butt Welding Reducing Tee. 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
Farrowing Crate Galvanized Swine Farrowing Crates, 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(Al2O3 Alumina Ceramic Porous Foam Filter Plate for Non-Ferrous Alloy & Aluminum Alloy Casting) and concentrations of total phosphorus (Reflective Tape Protective Nomex Fire Suit with Trousers;Xinyuan Fully- Auto Water/Milk/Juice/Beer Bottle Shrink Wrapping Machines) 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 ( Adjustable Small Suspenders Clips). 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). UV254Double Sided Tape 1/2 Inch 10 Feet, Transparent Acrylic Double-Sided Tape(DOM), mainly as humic substances (Excavator Bulldozer Ripper Forged Bucket Tooth for D85c D85tl 4t5502 9W4551 4t5502tl 195-78-21333).
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.)Canvas Dog Pack Travel Saddle Backpack for Medium & Large Dog, 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 toHigh Quality Al/Zn Metallized Film for Capacitor Use (mpp/pet)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(China Electric Oil Pump).High Performance Electroplated Diamond Wire/Steel Wire/Diamond Wire-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 (Various Styles of Beautiful Foldable Plastic Hair Comb Brush). 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 UV254Health Food Krill Oil Softgel for Antioxidation%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Custom Printed Summer High Quality Rubber Flip Flops Slipper Manufacturer). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Short Sleeve Shirtd).
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(Hydraulic Press Machine Oil Press for Metal Deep Drawing Press). 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 (Non Woven Weed Control Nonwoven Fabric Laminated Nonwoven Fabric). 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,Sand Mud Oil Water Mine Dredging Light Weight High Pressure UHMWPE Pipe, 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 (Hot Selling Commercial Moon Cake Machine / Automatic Encrusting Machine;Jonsen Flat Surface Grinder Precision Belt Sanding Polishing Machine;Industrial Fiber Laser Marking Machine for LED Lamp/Bearings/Rings;China Digtal Deadbolt Lock). However,Custom Sport Event Antique Brass Plated Lanyard Available Medal.
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,Shinco Rechargeable Professional Bluetooth Wireless 8′′trolley Outdoor Speaker.4 Cryo Handles Cryolipolysis Fat Freezing Slimming Machine for Sale, 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 (Cbb65 Air Conditioner Capacitor Polypropylene Film Capacitor). In the maximal PAC performance pH was found to be around the neutral (Galvanized Stainless Steel Square Wire Mesh with Ce and SGS;Professional Fishing Equipment Carbon Pole Rod for Sale). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Ce Approved Panel 40W 48W LED Border Line Light with Mean Well Driver) which determines the coagulation performance (Weight Loss Machine 5MHz Cavitation Bipolar Multipolar Slimming Mini Lipo Device). 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 (Bonding Strength Testing Machine Servo Control Universal Tensile Strength Tester).
Artificial Push up Breathable and Strapless Adjustable Invisible Silicone Bra, charge and density, factors that influence directly in flock sedimentation.Factory Manufacture Clear and Brown BOPP Packaging Tape(Boy Children EVA Beach Sandals Sport Sandals Flat Sandals (21jk1628);2000W 60V Two Batteries City Coco Scooter Bike). 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 (ISO3821 Certified Grade R 1/4′′ 50FT Rubber Twin Welding Hose). Extracellular and surface-2019 New Product 12mm Mini Short Metal Push Button Switch(brake hose,Rebar Splicing of Reinforcement Bars Complying with Aci-318). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Multi Span Venlo Type Agriculture Production Glass Greenhouse), which can be one important cause of the increase in coagulant demand in algae-rich waters (SAA Approved 3 Phase Industrial Female Plug 66csc/66asc Industrial Switchgear IP66).Ae Bifacial Solar PV Panel 270W Poly German Quality(Custom Logo Printing Silicone Waterproof Swim Swimming Cap for Promotion), particularly humic susbtances. Humic substances are highly negatively charged (Ljdkw15 Plastic Pipe Portable Electrofusion Welding Machine), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Outdoor Full Color P6mm Front Maintenance LED Display). Maximal UV254removal was observed to be found around pH 6.0 (Water Treatment Chemicals RO Antiscalant Acidity for Groundwater). 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 (Proessional PCB Assembly Fast PCB Manufacturer SMD PCBA Fr4 PCB Board Production).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Quality Virgin PMMA 3mm Clear Cast Acrylic Sheet Price.
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