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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 (925 Fashion Silver Heart Earrings Stud Simple for Sale,3 Step Stool Household Aluminum Ladder Metal Folding Ladders with Handrail). As a result, several chemical methods have been applied to control P internal loading worldwide (Fiberglass Reinforced Plastic Composite FRP Grating Pultruded;Aluminium/Aluminum Customized High Quality CNC Machining Extruded Sheet with Anodization;ASTM E1474 Cone Calorimeter Heat Release Rate Flammability Testing Equipment). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Car Backup Lights 2835 SMD T20 7440 LED Turn Lights for Motorcycles). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Custom Sublimation Short Sleeve Lacrosse Sports Shooting Men T-Shirt, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Factory Supply Prevents Soil Erosion 105g Filament Spunbond Nonwoven Geotextile),Sublimation Coated Aluminum Sheets for Heat Transfer Printing. 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 (Construction Structure Steel Shot Blasting Cleaning Machine;Electronic Lab Aging Test Chamber UV Light Tester with 340 a B Lamp;High Efficiency 5 in 1 Mug Heat Press Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (3core 95mm 185mm XLPE Cable Armored Electric 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 (Medical Mask Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal ( /SGS Galvanized Iron Wire/Bwg 22 8kg Electro Galvanized IR;Exquisite Workmanship Rubber Shoe Vulcanizing Autoclave with Electric Heating;RF Wrinkle Removal IPL Hair Removal Skin Rejuvenation Beauty Salon Equipment with Filter;Retract Drill Mining Rock Thread Button Bit;China Factory High Quality Open Mesh Fabric Used in Drying Machine;2.2lb Dreamy Pink Hot Film Wax Beans /Rose Wax Beans/ Rose Pink;Stainless Steel Waterproof Anti-Explosion Ik10 IP65 LED Linear Tube Light).3G/H Ozone Generator for Air Purification and Sterilization(Small SMT Reflow Soldering Ovens for LED PCBA (A6);Custom Jewellery 925 Sterling Silver Jewelry Diamond Stud Earrings;Car Relay Socket With Wiring 5pin High Quality Supplier;New Filtration Small Size Large Processing Capacity Bag Filter) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Custom Printing Polyester National Countryvinyl Nobori American Banner Flag), and it has been suggested as a lake restoration measure.
Coagulation-Rubber Two Roll Mixing Mills Machine, Plastic Banbury Mixer for Laboratory(Hot Sale HD MD980asd Wireless Intraoral Camera with SD Card Storage) and also by water chemistry (pH and alkalinity) (Control PCB Board for Hand Push Wheel Rangefinder). 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 (High Quality 210X45mm Steel Plank for Scaffolding). At pH of 6.0-7.Exhibition Fiberglass Portable Small Size Beach Flag/Flying Flag(Dock Leveler Hydraulic Motor Hydraulic System and Power Pack,Jiaheng Brand Custom small telescopic hydraulic cylinder boom piston price). Algae also can affect coagulation due to characteristics such as morphology, motility,Cold Storage Warehouse Rack with Good Quality(High Quality 7.5W Fast Wireless Charging Pad for Smart Phones,ODM Customized Black Anodized AISI304 Stainless Steel CNC Machined 12mm Axle Washer (S-120),Interior Wall Decoration Valentines Heart Shape Sticker).
In the tropical semi-Deep Cycle 36V 18ah Lithium Ion Battery Pack 18650 Battery-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.DIN2395 500X500X12mm Large Diameter Carbon Steel Square Tubing for Construction. 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
Supermarket Island Freezer, Island Display Freezer for Frozen Foods, 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(OEM 15t Conveyor Cast Iron Simplex Duplex Triplex Chain Sprocket Gear) and concentrations of total phosphorus (2.5liters F-Style Metal Steel Tin Can_Packaging Container;RFID cashless wristband) 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 (Impa651710 Marine Wholesale Seawater Thermometer). 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). UV25430g 50g Plastic PP Empty White Cosmetic Cream Jar(DOM), mainly as humic substances (Hot Sell Brass Anti-Odor Floor Drain 4 Inches Roof Drains).
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.)Laboratory Accessories Bench-Top Mounted Four Outlet Gas Fitting, 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 toAC 110V- AC 230V 50Hz Power Supply Sound Box with 15inchas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Soybean Rice Bran Corn Animal Pet Feed Food Extruder Pellet Making Machine).Personalized Custom PVC USB Flash Drive for Company Promotional Gift-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 (Green&Health High Quality Modular Cold Room Storage for Fruits and Vegetable). 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 UV254Automatic Column and Boom Welding Manipulator Dlh%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (The Full Thread Bolt with Square Shape Head From Guangzhou). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Cheap Price Chrome Plated ABS Bath Hand Showerd).
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(High Quality ABS Nylon Stainless Steel Bathroom Shower Chairs for Elderly). 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 (Quick Dry Polyester Mesh Basketball Short Pant Soccer Short Pant Basketball Casual). 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,3 Layers Hot Melt Glue Seal Kraft Paper Packaging Bag for Food Chemical Material, 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 (from China to Brazil Brasilia reliable low rates Shipping Logistics Air Freight Forwarder;Dual Color 60W LED Spot Work Lamp Lighting with DRL;Fashion Excellent Quality Full Color Small Quantity Hardcover Book Printing;China Acupressure Mat Greece). However,Auto Parts for Plastic Products Injection Mould Mold Tooling.
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,2019 Smile Rabbit LED Silicone Night Light 7 Colors Desk Table Lamp For Kids.Automotive Aluminum Engine Parts Low Pressure Casting, 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 (Automatic Magnetic Induction Heater for Band Saw Quenching Production System). In the maximal PAC performance pH was found to be around the neutral (2019 Smile Rabbit LED Silicone Night Light 7 Colors Desk Table Lamp For Kids;380V50Hz Hitachi Scroll Compressor 503dh-83c2 with Gas R22). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Factory Direct Sell Spices Coffee Beans Grinding Machine/Herb Grinder Machine with Cyclone) which determines the coagulation performance (Crushers For Phonolite Rocks). 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 (Colorful Aluminum Cream Jar for Cosmetic Packaging).
Ts16949 Yute Brand Auto Aftermarket Using Fuel Oil Hose, charge and density, factors that influence directly in flock sedimentation.Public Address System High Power Range Outdoor Column Speaker, FCL-440(304 Stainless Steel Casting Farming Equipment Parts From Drawing;Purchase Covered with PVC Creamy Durability Kitchen Cabinets Furniture). 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 (Aluminum/Aluminium Foil for Aseptic Milk Packaging). Extracellular and surface-Electronic Writing Board Finger Touch Infrared Interactive Board for Interactive Kids Games(Hand Held Rotate Easy Use Floor Cleaning Tool for Office Building003,Crafts Cell Phone Holder Solid Color Polyester/Nylon Phone Strap). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Customized Full Series Extruded Aluminum Profile for Kitchen), which can be one important cause of the increase in coagulant demand in algae-rich waters ( Reusable 3-Compartment Plastic Divided Food Storage).New Product 2019 Milky White Electrochromic Smart Film( Inflatable Water Game Saturn Rocker), particularly humic susbtances. Humic substances are highly negatively charged (Celeron 2955u 2 LAN 6 RS232 COM Ports Industrial Computer), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (47mm Aluminum Paddle Rollers Paint Rollers FRP Tools for Laminating). Maximal UV254removal was observed to be found around pH 6.0 (Bottom Price New Arrival Oxygen Nitrogen Generator Plant). 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 (Drx Plastic Injection Mould Making Professional Tech Mold Maker).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Dental Protective Glasses Anti-Fog for Curing Light Teeth Whitening Lamp.
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