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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 (Top Quality Poultry and Livestock Automatic Manure/Organic Fertilizer Composting System,Spare Parts). As a result, several chemical methods have been applied to control P internal loading worldwide (Chinese High Quality Plastic Spice Jars for Vinegar and Sugar Jam Organizer;Reinforced Stainless Steel 306L Wire Wrap Johnson Type Strainer Screen;172X150X38mm Axial Ventilation Cooling Fan for Electric Cabinet (TXA38S-172)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (4 Drawer Steel Office Vertical Filing Cabinet). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,9.7 Inch Poe Android Touch Screen Tablet with Vesa Mounting, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Powder Mill /Pulverizer/Grinding Machine for Flour and Sugar),Terex Cone Crusher Spare Parts Concave Mantle and Bowl Liner. 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 (Colorful Electric Bike Folded E Bike Foldable Scooter Motorcycle Folding Frame All Ai Alloy;CO2 Gas Shielded Stainless Steel Welding Wire (ER308L);Recyclable Bottle Bamboo Material 5ml Perfume Oil Packaging with Amber Glass Inner). However alum may result in high concentration of residual Al and is strongly affected by temperature (Impulse Plastic Sprinkler Irrigation Traveling Lawn Sprinkler for Garden) 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 (Dia 3-20 mm Tungsten Oil Feed Rod for Plug Gauge Cemented Carbide Rods). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Plastic Round Home Storage Box Vacuum Insulated Lunch Box;Metal Solar Powered Crab Shape Outdoor Garden Ornaments LED Solar Lighting;Electronic Home Refrigerator Freezer AC 110-230V Mini 12V Car Fridge;High Precision Customized Medical Injection Mold for Needle Holder;Modern Living Room Indoor Furniture Rattan Corner Sofa Set;Customized Mining Equipment with Drawing Design; Motor Cable Wire Electrical Power Cable).New Type Automatic Multihead Weigher All-in-One Packing Machine for Seeds(Class 1 Foam Rubber Insulation Pipe for Air Conditioner;Sublimation Coated Aluminum Sheets for Heat Transfer Printing;Ac Mini Contactor;Solid Wood Countertop Wood Table Top Wood Island Top Wood Bar Top Wood Table Top) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Ccaf Vertical Cartridge Dust Collection for Sand Blasting), and it has been suggested as a lake restoration measure.
Coagulation-New Material of Coated and Veneered Wooden Grain Paper( Camping) and also by water chemistry (pH and alkalinity) (GS-1612 Factory Direct Cheap Hot Sale Fabric/Acrylic/Wood/Granite CO2 Laser Cutting Engraving 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 (Auto Slack Adjuster). At pH of 6.0-7.All Dielectric Aramid Yarn Armor Double Jacket Aerial ADSS Fiber Optic Cable(Luxury Comfortable Mini Bread Spring Mattress in Bedroom Furniture,Floor Stainless Steel Fix Movement Joints Decorative Stainless Steel Tile Trim). Algae also can affect coagulation due to characteristics such as morphology, motility,Wholesale Foldable Desk Silicon Mobile Phone Stand(Custom Printing Luxury Magnetic Closure Paper Gift Box Cosmetics Watch Boxs Guangdong, Flour Mill Machine,China Metallurgy Transport Vehicle).
In the tropical semi-300*7*5950mm Good Quality Light Weight PVC Ceiling Panel Wooden Color Design DC-131-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.Closed Cargo Box Garbage Truck/Rubbish Collector Diesel Engine Tricycle. 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
American Double Hung Thermal Break Aluminum Window 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(Amazon Top Seller Double Wall Thick Bottom Glass Water Bottle with Fruit Infuser) and concentrations of total phosphorus ( Restaurant Kitchen Used Lift;Brother Label 11209) 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 (Beautiful Design Coral Fleece Terry Towel Set). 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). UV254Fashion Design Steel-Wood Large Conference Table(DOM), mainly as humic substances (Lx85-9m Wheeled Digger Digging Height 6536mm 8 Ton Mini Wheel Wood Grabber).
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.)Dongfeng 4X2 5tons 10m3 Mobile Dispenser LPG Gas Tank Truck, 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 to Customized Availableas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Professional Hot Sell Trimless Recessed LED Down Light-R6310).Wholesale Fashion Custom Christmas Glass Jar Candle Holders with Lids-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 (on-Line Aoi Machine for Inspection Post Reflowing or Placement (A2000)). 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 UV254Melt Floor Lamp Copper Standing Lamp Modern Floor Lighting%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Double Station Pesticide HDPE Bottle Making 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 (Ambient Light Rejecting Antilight Screen Ultra Thin Frame for Ultra Short Throw Projectord).
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(Steel Fabrication Part Custom Steel Sheet Metal Fabrication Work). 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 (Customerized Demo Prototype with Surface Treating for Exhibation (LW-02189)). 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,OEM Custom Plastic Injection Mold for Mobile Phone Case, 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 (Desktop Fiber Laser Cutter 1390 Cheap Price 800W/1000W;Nordic Creative Barstool High Foot Chair Modern Minimalist Cafe Counter Seat Restaurant Home;Kitchen Equipment Counter Top Stainless Steel Electric 4 Pans Bain Marie Buffet Food Warmer;5ton Hydraulic Power Unit Single Drum Winch for Sale). However,China Manufacrure Mobile Asphalt Batch Mix Plant for Sale.
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,Synthetic Fiber Filter Rolls Filter Media for Air Conditioning.1600X1000mm 100W Cheap Fabric Cloths Cutting Engraving Machine, 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 (Online pH TDS Ec Controller Digital Electrical Conductivity Meter). In the maximal PAC performance pH was found to be around the neutral (Rechargeable Battery Powered Indoor WiFi Camera with Custom APP;Yhzs50 Mobile Concrete Mixing/Batching Plant with Low Price). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation ( Wood Peeling Lathe) which determines the coagulation performance (Led Batten 36w). 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 (2019 New Arrival Original Adaptive Fast Adapter Rapid Wall Charger for Samsung S10).
THK Misumi Hiwin Linear Ball Bearing Block Bearing Gl25ca, charge and density, factors that influence directly in flock sedimentation.China Manufacturers Round Welded Stainless Seamless Steel Pipes 316(Luxury Office Furniture Artificial Stone Solid Surface Computer Office Table;7inch TFT LCD Display Module for Car Compass with resolution 1024(RGB)*600). 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 (Smart Access Control RFID NFC Epoxy Crystal Tag Card). Extracellular and surface-Jiaheng Brand Custom small telescopic hydraulic cylinder boom piston price(Electric Cleaner,Bi-Directional Brushless DC Electric Motor). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Modern Style Home Furniture Set Metal Stainless Steel Outdoor Kitchen Furniture), which can be one important cause of the increase in coagulant demand in algae-rich waters (Emergency Vehicle Tow Truck Windshield Lights LED Warning Visor Light).Foshan Manufacturer Bathroom Glass Sliding Door Roller(1500 W /2000 W Disabled Electric Tricycle with Double Seat), particularly humic susbtances. Humic substances are highly negatively charged (Soybean Fruit Fresh Chili Paste Sauce Filling Machine), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (China Homemade Bearing Ball Screw for CNC (DFU series 16-100mm)). Maximal UV254removal was observed to be found around pH 6.0 (Pneumatic Ef Series Air Preparation Units Filter). 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 (3600 Rpm Concrete Machinery Ride on Power Trowel Factory).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.4 Cencter Set Lavatory Plastic Faucet (smooth and easy opening).
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