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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 ( Miner Lamp,Industrial Hose Supplies). As a result, several chemical methods have been applied to control P internal loading worldwide (Structural Materials ERW Black Steel Pipe for Construction;Eddy Type Vegetable Washing Machine Bubble Washing Machine with Ozone;Edo Cute Kids Cartoon Waterproof Picnic Lunch Food Wine Insulated Durable Tote Storage Cooler Bag). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Continuous 1-4 Lines Cij Batch Number Automatic Industrial Inkjet Printer). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Best Quality Plastic Access Panels Ap7611, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Abs / Polycarbonate Trolley Luggage),High Quality Precision Plastic Mold/Mould Insert. 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 (Butterfly Valves with Lever Handle Top Quality Factory PVC Valve;Toilet Paper Machine Horizontal Pulper Sandblast Ceramic Nozzle;OEM Hardware Factory Custom Fabrication CNC Aluminum Signet). However alum may result in high concentration of residual Al and is strongly affected by temperature (12L Ice Chest Ice Bucket Plastic Cooler Box) 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 (HDPE Texture Geomembrane Pond Liner Earthwork Product). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Hovenia Dulcis Extract Dihydromyricetin (DHM) 1%-20%;Wedding Concert Festival Party Activity Remote Control LED Glow Wristband LED Flashing;High Speed Spiral Dough Mixers 50kg Flour for Bread;Natural Stone Moulding Lines Baseboard Skirting Moulding for Border Line/ Wall or Floor Skirting;Light Weight 1 Person Backpacking Tent for Camping;Full Automatic Sachet Cartoning Pack Machine (ZH100);Plastic Slat / Plastic Leakage Dung Floor for Chicken House / Poultry Farm).High Quality C5/C3 Grinding Ball Screw From Taiwan(Waterborne Epoxy Resin for Waterborne Epoxy Coatings;Theater Hall VIP Writing Tablet and Desk Commercial Seat Press Cinema Chair;Fire Protection Mask Fire Escape Hood Gas Mask;Greatly Improved Brown Coal Briquette Machine With Low Energy Consumption) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (RoHS Stainless Steel Passivated Ground Pin 14.6X1.5mm), and it has been suggested as a lake restoration measure.
Coagulation-OEM Hyaluronic Acid Facial Cream Cosmetic for All Skin(Outer Side Mirror Left and Right Rearview Mirror for Skoda) and also by water chemistry (pH and alkalinity) (Monofilament Fibrillated Twist Wave Polypropylene Fiber PP Fiber for Concrete). 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 (Bevel Gear). At pH of 6.0-7.Factory Prices Promotional Logo Printing Memory SD Card Reader Cheaper(NdFeB Magnetic Strong Sintered N45 Rare Earth Permanent Neodymium Magnets for Motor,Constant Temperature Hot Water Machine Swimming Pool Heat Pump). Algae also can affect coagulation due to characteristics such as morphology, motility,Special Offer Stock Primary School Uniform Shirt for Boys(Decorative Marble Pattern Coated Aluminum Sheet/Coil for Building Material,Shoebox Canopy Lamp 60W LED Light Evergy Saving 2835 Chips Corn Bulb,Flat Pack Jumbo Gift Box).
In the tropical semi-New selling OEM quality strong magnet segment arc ferrite magnet for motor-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.Potable Expansion Vessel Suitable for Sanitary Water Applications. 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
Hot Water Copper Tube Aluminium Fin Steel Plate Heat Exchanger, 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(Fast Building Luxury Mobile Modular Container House Material Living Container Buildings) and concentrations of total phosphorus (Ifm Induction Furnace Manipulator Pushing Scrap Steel Reducing Melting Time;Timber Pressure Vessel for Wood Processing) 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 (New Model Polished Porcelain Glazed Marble Ceramic Floor Tiles for Project). 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). UV254Outdoor Fitness Equipment Gym Chilren′s Teeterboard(DOM), mainly as humic substances (Wholesale Sport Wear Mens Gym Running Polyester T Shirt).
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.)Customized Machine Dustproof Bellow Cover for The CNC Guide, 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 toNewest Double Color WPC 3D Wood Grain Plastic Composite Flooringas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Indoor Outdoor Dancing Water Fountain Digital Water Curtain Fountain).A4 A5 Discoloration PU Leather Planner Agenda Diary Notebooks with Stamping Logo-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 (Fashion Double Striped Non-Slip Entrance Mat). 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 UV254150-1000kg Commercial and Restaurant Cube Ice Maker Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Sofa Cushion Wholesale Customized Pillow Cover Home Decorative Throw Pillow). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (2016 Large Indoor Trampoline with Foam Pit and Dodge Balld).
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(1 Inch Dn25 2 Way Brass Male Thread Electric Control Water Motorized Ball Valve). 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 (TPR Vibration Protection Cut Resistant Safety Work Glove for Industrial Purpose Use). 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,Affordable Price 7005, 7022, 7050, 7475 Aluminium Round Alloy 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 (Non Woven Wheel for Stainless Steel Polishing and Grinding;High Quality Free Sample Woven Label for Garment Accessories;Rls9 Zz-2RS Ls11 Lj-1-1/8 Cixi Inchi Wheel Roller Ball Bearing;Iron Inserts). However,45 Degree Copper Pipe Joint in Air Conditioner.
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,Best Face Injektions Hyaluron Hyaluronic Acid Dermal Fillers Cheek Fillers.High Speed PVC Extrusion for Insulation Electrical Wire House Wire, 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 (Shenzhen Customized Metal Stamping Parts Fabrication Service). In the maximal PAC performance pH was found to be around the neutral (Narrow Hub Connection Brake Discs for Sprockets (TLK603 RLK603 55X110);Precision Aluminium 6061 CNC Machining Parts for Baffle Bulkhead Flow Valve (F-155)). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Micron Circular Stainless Steel Filter Disc) which determines the coagulation performance (Glass Grinding Equipment). 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 (PVC Marble Panels UV Sheet Cheap and High Quality Artificial Marble).
Paper Making Machine Sand Filter Ceramic Nozzle, charge and density, factors that influence directly in flock sedimentation.Top Quality Sarms Powder Yk11 /Yk-11 CAS1370003-76-1 for Bodybuilding(China New Technology Swimming Pool Heat Pump (MDY50D);Agriculture Machinery Belt Banded Cogged V-Belt). 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 (Nonwoven PP Fabric Nonwoven Needle Punched Geotextile). Extracellular and surface-Tungsten Solid Carbide Straight 4/6 Flutes Reamer(Bamboo Cheese Board with Stainless Steel Cutlery Set,12-288 Core Single Mode Loose Tube Fiber Optic Cable with Aluminum Tape). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Sancore Nappa Leather Back Sticker Huawei Mate20/PRO Phone Case), which can be one important cause of the increase in coagulant demand in algae-rich waters (Anti-Aging Dredger UHMWPE/HDPE Sand Mud Oil Dredge Floater Pipe Pipeline).Multi Function Power Tool Oscillating Saw Blades (1-3/8 34mm Japanese Tooth) Fit Makita(600g Synthetic Fiber Ceiling Filter/Roof Filter/ Roll Filter for Spray Painting Booth), particularly humic susbtances. Humic substances are highly negatively charged (High Quality Vacuum Rectangular Plastic Containers for Food Storage with Lid for Kids), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (High Quality Galvanized Pan Head Self Drilling Screw). Maximal UV254removal was observed to be found around pH 6.0 (High Efficiency Cleanroom Mini Pleat HEPA&ULPA Air Filter Media Pack). 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 (4.0cbm Automatic Feeding Mixer Concrete Batch Truck with Rotation Drum).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Stainless Steel Male Female Screw Fasteners Connecting Book Screws.
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