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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 (Synthetic Fiber Filter Rolls Filter Media for Air Conditioning,Forged Eye Lags). As a result, several chemical methods have been applied to control P internal loading worldwide (Must 4kw 2HP Pump Power Inverter Ags Bts Available;Prefab Factory Price High-Quality Modern Shipping Container Clinic;Comfort Rubber Cow Stable Stall Rubber Matting/Mattress/Mat with Fabric Insertion). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Customized Dummy Animal Teething Toy Design Baby Pacifer). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Customized Cutting Tool Solid Carbide Tool Taps (TS-100002), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Alumina Aluminum Oxide Filtration Fabric Filter Belt),Three Lines Production Three Side Seal Pouch Making 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 (KERONG Electronic Keypad Digital Combination Hardware Glass Locks For Lockers′ Safes;High Purity Calcined Alumina Micro Powder for Ceramics Refractories;Kids Waterproof Cow Leather Wool Felt Warm Fur Boots for Winter). However alum may result in high concentration of residual Al and is strongly affected by temperature (Coating Precision CNC Auto Spare Machinery Parts Turning and Milling Industry) 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 (Protective Knee Pads For Work). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (10 Supply Water Pipe Insulation HDPE Outer Pipe;Coms Camera Factory Vari-Focal Lens DVR Camera Web Camera Bullet;Reducer Hydraulic Fitting with Swivel Nut (2D);High Manganese Mn13cr2 Mn18cr2 Jaw Plate Crusher Parts;Aluminium Downpipe Downspout Elbow Roll Forming Machine;Colorful Commercial PVC Vinyl Flooring for Office;Auto Air Poppet Valves Cover Plastic Mould / Mold).Auto Price Crankshaft Position Sensor 90919-05043(African Trapezoidal Triangular Pulley Roller for Sliding Gate Door-Silvery;High Sensitivity Metal Detector for Security Inspection;Filling Machine Khs;High Power/Torque Density 7.5kw 2500rpm AC Servo 3 Phase Motor) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (10W Auto Oval Work Car Light Blue Red LED Forklift Warning Head Lamps), and it has been suggested as a lake restoration measure.
Coagulation-Food Grade PVC Water Suction Hose / PVC Corrugated Suction Hose(Prefab Multifunctional Steel Structureg for Wholesales Construction Material) and also by water chemistry (pH and alkalinity) ( Paper Bags). 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 (27 FT Cabin and Hard Top Aluminum Leisure Boat for Fishing). At pH of 6.0-7.Karl Mayer Machine Warp Knitting Spare Parts Karl Mayer Machine Pulley Belt(A2 Fireproof Inorganic Mineral Material for A2 ACP Panel ACP Sheet,304 Stainless Steel Pipe Manufacture in China). Algae also can affect coagulation due to characteristics such as morphology, motility,Textile Screen Printing Mesh Polyester Material(Hospital Equipment 23L Benchtop Autoclave,Light Controller DMX Controller for Stage Light,Personalized U Shape Cute Funny Plush & Stuffed Pillow).
In the tropical semi-Hot Selling HOWO Heavy Truck 371HP Dump Truck, Tipper, Dumper Truck-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.High-Class Sld-6121 Paper Sticker High Speed Slitting 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
Factory Price Smart Handheld Printer V5 Hand Jet Printer Handheld Code Printer for Carton, 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(Fasion Style Custom Indian Embroidery Patch) and concentrations of total phosphorus (Cummins auto diesel engine motor 6ISBE parts 4892338 starter motor;OEM Professional Molding Maker Custom Plastic Injection Mold Shanghai) 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 (Plastic Reflective Raised Pavement Marker Road Stud). 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). UV254Farm, Garden Irrigation Gasoline Water Pump Wp20, Wp30, Wp40(DOM), mainly as humic substances (Automatic Acrylic Plastic PVC Plate Bending Machinery Improved Style).
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.)Commercial Industrial Fast Food Chicken Electric Gas Pressure Deep Fryer for Mijiagao, 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 toWinter Warmer Windproof Ski Full Face Mask Cover Hat Cap Outdoor Sports Balaclavaas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(3mm Beveled Edge Clear Safety Silver Mirror Glass High Quality Supplier).220V Square Synchronous Grill Rotisserie Motor for Gas Cooker-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 (Water-Proof Silicone Coated Fiberglass Cloth). 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 UV2545r 200W LED Moving Head Beam 3 in 1 Stage Lighting%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Stable Quality Vacuum Heat Treatment Atmosphere Sintering Furnace). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Indoor or Outdoor FTTH 8port Wall Mount Fiber Optic Terminal Box and FTTH Distribution Boxd).
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(Custom Polyester Woven Patch Logo Snapback Hats). 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 (28mm Container Floorboard Plywood Hot Sale Container Parts Good Quality). 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,Picnic Lunch Bag Waterproof Tote Lunch Bag for Kids Adult, 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 (Double Side Painted Aluminium Coil Plate with PE Film;Cation Printing Effect Micro Fleece;2 Head Embroidery Machine Cap Flat T Shirt Embroidery;Home Reverse Osmosis RO Membrane Cleaning Water Treatment Filters Reverse Osmosis Membrane 3012-). However,Steel Structure Welding Steel Structure Metal Building.
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,Chc-B07 Health Stainless Steel Germanium Bracelet for Female, Oppbag.92 16: 9 Motorized Projection Screens with Black Casing, 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 (Tri-Axle 50tons 60tons 18m Low Loader Lowbed Trailer Axles). In the maximal PAC performance pH was found to be around the neutral (Girl Bedroom Mermaid Design Cute Sweet Silk Cotton Printing Duvet Cover Comforter Cover Quilt Cover;Silicon Baby Bib Super Waterproof with Food Slot). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (99.999% Sio2 Quartz Grain Sand 100-200 Mesh for Quartz Rod) which determines the coagulation performance (436 430 Stainless Steel Sheet Price Philippines Color Stainless Steel Sheet). 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 (Spot Supply Al2O3 85% Bauxite Use for Calcined).
Alloy 6063 T5 Temper Aluminium Extrusion Customized Round Tube/Flat Tubes, charge and density, factors that influence directly in flock sedimentation.Colorful LCD Display High Quality Cheap Price Optical Fiber Fusion Splicer, Splicing Machine S6(Industrial Dust Filter Aramid Nomex Fiberglass PTFE Fabric Filtration Fabric;High Quality Nylon Monofilament Suture Medical Nl Suture Thread with or Without Needle). 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 (304 Stainless Steel Deep Drawn Parts for Kitchen Equipment). Extracellular and surface-15m 17m 3 Arms R Shape Trailer Mobile Spider Concrete Placing Boom on Sale(Boho Gold&Silver Antique 3 Circle Hoops Pendant Earring for Women,9oz 16oz 17oz Stainless Steel Water Bottle BPA Free Metal Water Bottle for Promotion). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (10 Years Factory Free Samples Competitive Price Black Duct Tape with Custom Logo), which can be one important cause of the increase in coagulant demand in algae-rich waters (Optical Fiber Cable MTP/MPO Cassette for Data Center).Geekvape Aegis Squonk Tc Kit 100W Wholesale Price E Cigarette(High Tensile Wire Rope Lifting Jaw Jaw Turnbuckle Rigging), particularly humic susbtances. Humic substances are highly negatively charged (Chitosan with Glucomannan Dietary Supplement), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Touch Screen Digitizer LCD Display Assembly for Samsung Galaxy J720). Maximal UV254removal was observed to be found around pH 6.0 (Low Temperature Extended Stem Cryogenic Forged Steel Gate Valve). 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 (High quality 110V DC Power Supply for American Market).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Skin Cool Cold Hot Hammer Electroporation Machine for Facial Lifting (VS-885).
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