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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 (Auto Electrical Heater Blower Motor for Benz 2208203142,20 Years Professional OEM Factory of Laundry Liquid Detergent). As a result, several chemical methods have been applied to control P internal loading worldwide (Enuo DIN En 853 856 Flexible Oil Rubber High Pressure Hose;Export Quality Flavor Fresh Ramen Mixed Noodle with Turkey Sauce;Factory Cafe Furniture Rectangular Dining Table). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (2019 China Professional PE/PP Knotless Net Extrusion Line Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Copper Standard Multi 2/4/6/8 Cores Alarm Cable Security Monitor System, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Free Design Custom Used Aluminum Roof Lighting Truss Display System),Galvanized Wire Rope Sling with Eyes at Both Ends. 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 (Aluminium Fabric Garden Coffee Shop Outdoor Dinning Chair;Tube Polished Heat Resistant Al2O3 Alumina Zro2 Zirconia Ceramic Pipe;BAA9A79 Single Wall Borosilicate Square Drinking Glass Cup with Handle). However alum may result in high concentration of residual Al and is strongly affected by temperature (Waterproof 2 Ball Trailer Hitch Lock Trailer Stainless Steel Lock) 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 (Ibeacon Quality Control). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Zinc Alloy 103 Mailbox Post Tubular Drawer Cabinet Cam Lock;Liberty Furniture Cotswold Upholstered Dining Arm Chair in Cinnamon;for Bahrain Market Hot Cafe Vending Machine F303V;China Supplier PPGI Coils for Construction Materials;Water Spray Fruit and Vegetable Air Bubble Washing Machine;HOWO 8X4 Aluminum Alloy 35000L Gasoline/Oil/Fuel Tanker Truck;High Accurate LCD Digital Medical Flexible Oral Thermometer).China Supply 3 Inch Rubber Hose High Quality Heat-Resistant Steam EPDM Rubber Hose(Flat Screen 15 17 19 24 32 Inch Smart HD Color LCD LED TV;Panasonic Ai Spare Parts X004075 with Large Stock;Cad Jewelry Design Ring Wholesaler Quotes & PriceList;Ceramic Components Applied in Machinery Industry) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (EPS100 Nts100 Xns100 Common Rail Injector Test Bench), and it has been suggested as a lake restoration measure.
Coagulation-XCMG Official 150 Ton Rough Terrain Crane Rt150(BS5163 Metal seat non-rising stem cast iron gate valve PN16) and also by water chemistry (pH and alkalinity) (12mm Thickness Square Corrugated Cake Board). 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 (Dog Food Making Machine). At pH of 6.0-7.China Factory Fluorescent Neon Powder Pigments, Cosmetic Fluorescent Pigment Powder Manufacturer(Customized EPDM NBR Rubber Bellows Expansion Joint,Tunnel Wall Light IP65 240W Outdoor LED Building Exterior Lighting). Algae also can affect coagulation due to characteristics such as morphology, motility,1 Inch Dn25 2 Way Brass Male Thread Electric Control Water Motorized Ball Valve(Non-Slip Baby Kids Fashion PVC Rain Boots,High Axial Flow Clean Water Submersible Sump Irrigation Pump,Lithium Cordless Drill).
In the tropical semi-Wire Rope Clips Us Type Galvanized Drop Forged Cable Clamp-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.Osyea 2019 Outdoor Power Solar Garden LED Street Lamp. 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
Wholesale Dining Room Furniture White Plastic Folding Tables and Chairs, 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(Wholesale Plastic HDPE Foldable Rectangle Folding Wedding Tables) and concentrations of total phosphorus (Rigid 94V-0 PCB Fr4 Double-Sided PCB with 1.6mm Thickness 2 Layer;Fabric Rapid Fast Plastic Roller Shutter Rolling High Speed Doors) 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 (Simple 3 Fold Orthopedic Folding Foam Mattress). 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). UV254Stainless Steel Handrail Long Bar Holders for 12mm Pipe(DOM), mainly as humic substances (Wholesale Oil Tanker Trailer 3 Axle 42000L Trailer Fuel Tank Semi Truck Trailer).
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.)Cheap E306D E330d Caterpillar Cat Excavator Water Cooling Radiator, 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 toLinkable PIR Motion Sensor Indoor LED Linear Strip Under Cabinet Lightas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(www.mphotoluminescent.com).Ce Factory Sale Waste Logs Drum Wood Chipper-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 (Quality Medium Stapler with Staples Remover). 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 UV254Take Away Custom Logo Printing Snack Paper Pizza Box Packing%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (G02f12L Tempered Glass Shower Cabin). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Stepper Motor Driver Priced).
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(Tandem Axle Semi-Trailer Lift Germany Mechanical Overslung Suspension). 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 ( 7050). 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,CNC Machining Milling Aluminum Bike Components, 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 (Pear or Regular Shaped Screw Lock Metal Quick Link;Traffic Safety Plastic Signs/Accessible Fire Exit Emergency Signs;Popular Lifejacket EPE Foam Life Vest for Water Safety Equipment;LED Projector 400W Bsw with Framing Moving Head Lighting). However,JIS G3441 Machining and Structure Alloy Steel Pipe.
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,250sv-Sp Mining Centrifugal Vertical Wet Slurry Pit Pumps.Micropile Tube as Umbrella for Tunnel Portal Od73mm Wt6mm, Steel Pipe, 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 (14G Auto Computerized Collar Flat Knitting Machine). In the maximal PAC performance pH was found to be around the neutral (Portable Metal and Nonmetal CNC Fiber Laser Marking Machine;Long Span Galvanized Light Weight Steel Structure). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (China Gingseng Extract Ginsenosides 15% 20% 80%) which determines the coagulation performance (Lab Glass Reactor Kettle Extractive Distillation). 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 Shoe Upper with LED Light for Kids Slide-on Slippers).
Household Multi-Function 16.8V Double Speed Lithium Cordless Electric Drill, charge and density, factors that influence directly in flock sedimentation.Portable Marking Equipment System Laser Wire Marking Machine Price(Plastic PVC Car Mat Making Line / PVC Coil Carpet Car Seat Cutting Machine;Duct Outdoor Single-Mode Gyfy Fiber Optic Cable). 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 (Handrail Fitting / Stainless Steel Round & Square Tube Connector). Extracellular and surface-3-Ply Copper/Stainless Steel Cookware Set with Hammer Patten, Kitchen Utensils, Dutch Oven(3500lbs Cable Pulling Fast Line Speed UTV Electric Winch,Kitchen Stainless Steel Washing /Wash Double Bowl White Sink). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Factory Price 50W LED Corn Bulb E26/E39/E27/E40 Base Indoor and Outdoor Industial Lighting), which can be one important cause of the increase in coagulant demand in algae-rich waters (FRP Insulated PU Foam Composite Panel for Refrigerated Truck Body).200/375/500ml Empty Crystal Vodka Glass Wine Bottles Straight Decanter(Whole-Sale 25cm Cleanroom M3 Wipes Cleaning Tissue Cellulose Wipers), particularly humic susbtances. Humic substances are highly negatively charged (Rubber Hose Gasket), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (1325/1530/2030/2040 CNC Woodworking Router Machine with Cheapest Price and Big Discount Is on Big Sale). Maximal UV254removal was observed to be found around pH 6.0 (Wholesale Portable Travel Bamboo Tooth Brush Holder). 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 (Wholesale Brosilicate Glass Smoking with Black Triple Layer /Triple Arm Straight Glass Water Pipe).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Log Debarker, Peeling Head, Log Peeling Head, Heavy Duty Log Peeling Head, Wood Peeling Lathe.
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