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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 (OEM CNC Machine Machining Textile Machine Accessories,14 Inch Laptop Backpack). As a result, several chemical methods have been applied to control P internal loading worldwide (Simple 3 Fold Orthopedic Folding Foam Mattress;Wholesale Oil Tanker Trailer 3 Axle 42000L Trailer Fuel Tank Semi Truck Trailer;Factory Price Resin Wedding Chairs for Sale). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Non-Bladder Single Tube Disposable Thigh NIBP Cuff of 45-56.5cm). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Hsc8 6-4A Mini-Type Self-Adjustable Crimping Plier, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (OEM Casting Service Automotive Parts Valve Cover Cylinder Head Cover),Customized Steel Wire Small Conveyor Belt System. 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 (Silica Gel Aerogel Thermal Insulation Materials Felts Fireproof Acoustic;Linkable PIR Motion Sensor Indoor LED Linear Strip Under Cabinet Light;20W 30W 40W Solar Lighting System Solar Street Lights for Road Lighting Fittings). However alum may result in high concentration of residual Al and is strongly affected by temperature (Round Pipe Welded Pipe Middle Size for Chemical Companies) 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 (Indestructible Steel Toe Work Shoes). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Quality Medium Stapler with Staples Remover;G02f12L Tempered Glass Shower Cabin;Cold Rolled Steel Coil Galvalume/ Hot Dipped Galvanized Steel;Tandem Axle Semi-Trailer Lift Germany Mechanical Overslung Suspension;Manufacture of Aluminium Composite Panel Price in India 4mm; 7050;115cm Mini Sex Doll for Man Big Breast Love Doll).12 Hooks Wood Coffee Mug Holder Rack for Kitchen Storage(Fancy Design Formal Dress Shirt Short Sleeve for Women;Pear or Regular Shaped Screw Lock Metal Quick Link;Grange Lap Fence Panel;Traffic Safety Plastic Signs/Accessible Fire Exit Emergency Signs) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Popular Lifejacket EPE Foam Life Vest for Water Safety Equipment), and it has been suggested as a lake restoration measure.
Coagulation-Industrial Fine Bubble Membrane Disc Air Diffusers for Waste Water(14G Auto Computerized Collar Flat Knitting Machine) and also by water chemistry (pH and alkalinity) (Portable Metal and Nonmetal CNC Fiber Laser Marking Machine). 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 M10 Nylon Washers). At pH of 6.0-7.Bearing Accessories Bearing Ball Bearing Rollers(Long Span Galvanized Light Weight Steel Structure,China Gingseng Extract Ginsenosides 15% 20% 80%). Algae also can affect coagulation due to characteristics such as morphology, motility,Automatic Control Apricot Shell Charcoal Carbonization Kiln Price(PVC Shoe Upper with LED Light for Kids Slide-on Slippers,Plastic PVC Car Mat Making Line / PVC Coil Carpet Car Seat Cutting Machine,Gel Cheertainer Container Supplier).
In the tropical semi-Water Cooled Vibrating Grate Boiler for Power Plant EPC-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.Anti Corrosion Zinc Rich Pure Epoxy Powder Coating. 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
Electric Convection Bread Bakery Oven Made in China, 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(Kitchen Stainless Steel Washing /Wash Double Bowl White Sink) and concentrations of total phosphorus (Factory Price 50W LED Corn Bulb E26/E39/E27/E40 Base Indoor and Outdoor Industial Lighting;49m Concrete Pump) 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 (1325/1530/2030/2040 CNC Woodworking Router Machine with Cheapest Price and Big Discount Is on Big Sale). 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). UV254Ce 20 Aluminum Frame City Electric Folding Bike with Lithium Battery(DOM), mainly as humic substances (Wholesale Portable Travel Bamboo Tooth Brush Holder).
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.)Brand New Forklift with Double Front pneumatic Tire, 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 toAutomatic Non-Woven T-Shirt Bag Making Machine with High Efficientas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(michemcel.com).Manufacture Tempered Glass Door Stainless Steel Curved Bottom Patch Fitting-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 (Personal Skin Care Silicone Sonic Facial Cleansing 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 UV254Car Fridge / Refrigerator Small for Hyundai Car%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (UV Coating Surface Treatment and Indoor Usage Plastic PVC/WPC/Spc Flooring Extruder Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Water Heater Accessories Hardware Packaging Machine Automatic Counting Screw Packaging Machined).
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(Customized Thread Cutter of M105*3.0 Large Cutting Tools for CNC Machine Tools). 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 (ASTM A53 Black Round Metal Carbon ERW Steel Pipe). 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,Cement Bag Manufacturer Kraft Paper Valve Bag for Cement, 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 (Two Sides Grey Silicon Coated Fiberglass Waterproof Roofing Fabric Cloth;Supply12HP Copeland Scroll Air Conditioner Compressor Zr144kce-Tfd-522 for Sale;15.6 Slim 30pin Edp Screen LCD Display N156BGA-Eb2 N156bge-Eb2 for Laptop Screen Replacement;Good Quality Galvanized Umbrealla Head Roofing Nails). However,W11H-20X2500 3 rolls Automatic plate industrial bending rolling machine.
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,Electric Commercial PC Roller Shutter Door for Sale.Custom Personalized Logos Cheap Neck Printed Custom Polyester Lanyards Ribbons with ID Card Holder, 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 (Quick Drying Waterproof Silicone Sealant Construction Adhesive Glue for Glass). In the maximal PAC performance pH was found to be around the neutral (12mm LED RGB String Light/ LED Pixel with SD Card Controller;Coupling Capacitor for No Partial Discharge Signal Detection). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (145g 5X5mm EPS Fiberglass Reinforced Wire Mesh Price for Plastering in Europe) which determines the coagulation performance (360 Degree Panoramic 2.0MP WiFi Smart Home Bulb IP Camera). 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 (Manufacturers Wholesale Microfiber Car Cleaning Towel).
Big Width Different Thickness Pet Release Film, charge and density, factors that influence directly in flock sedimentation.Spectrum Analyzer for Ferrous and Non-Ferrous Metals(High Precision Machinery Plastic Parts with Injection Mold; Type Dlo 2kv Msha). 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 (7 Custom Voice Blank Recordable Video Invitation Greeting Card). Extracellular and surface-18 Inches Double Shafts Driving Xk-450 Rubber Rolling Mill(Fashion Hot Sale Tortoise Shell Sunglasses,Easywell & Minston Electric Platform Scale with Height Meter BS-200lp). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Auto Styling Car Interior Accessories Central Armrest Storage Glove Trau Box for Ranger), which can be one important cause of the increase in coagulant demand in algae-rich waters (Burglar Alarm PIR Microwave Motion Sensor Srdt15).Animal Husbandry Equipment Cattle Farm Equipment Cattle Cow Headlock(Made in China Colored Heat Resist Strength Silicone Rubber O-Rings for Excavator), particularly humic susbtances. Humic substances are highly negatively charged (Airless Shot Blast Cleaning Machine), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Professional Manufacturer Large IR Touch Screen Monitor 32 43 55 65 Inch for Commercial Kiosk). Maximal UV254removal was observed to be found around pH 6.0 (Heavy Duty Double Ladder Trailer Top Tent). 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 (Deep Drawing 300tons Sheet Metal Stamping Hydraulic Press Machine 100tons).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Hydraulic Scrap Metal Baling Machine for Metal.
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