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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 (Potable Expansion Vessel Suitable for Sanitary Water Applications,Face Serum). As a result, several chemical methods have been applied to control P internal loading worldwide (IP65 Waterproof Exterior Hanging Batten Linear Lighting LED Tri-Proof Light;Transformer-Base Factory Equipment UPS 3 Three Phase in 3 Phase Output 60-400 kVA Online UPS;Forged Custom Exterior French Door Wrought Iron Double Entry Doors). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (92 16: 9 Motorized Projection Screens with Black Casing). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Three Phase Fan Water Pump Electric Asynchronous Induction Motor, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (15mm Thin Wall 316L 309S Stainless Steel Tube),Star Necklace Jewelry Wholesale Fashion 925 Sterling Silver Necklace Jewelry. 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 (China Supplier Customized Pressing Stamping Parts; 4 Butanediol Bdo CAS 110-63-4 with Lowest Price;Marine Studless Link Anchor Chain for Sales). However alum may result in high concentration of residual Al and is strongly affected by temperature (Woma Acrylic Shower Panel Cubicle Room for Old People (Y698)) 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 (New Arrival Korean Fish Crips Mobile Canteen Van). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (15t/H Hot Selling Professional Factory Price Palm Nut Crusher Machine with Ce;Rugged Construction Material for Steel Screens for Platforms and Floor Channels.;Htzh-2h Portable Sf6 6-in-1 Gas Comprehensive Analyzer;Cemented Carbide Round Rods;Party Game Factory & Manufacturer;Shenzhen Customized Fr4 FPC Flexible Circuit Board Customized PCB Manufacturing PCB;Difference Between PPGI and PPGL of Price and Type).Competitive Wholesale Price Nicotine Salt E Liquid Vgod Mango Bomb( Dumper Truck; ISO9001;Artificial Grass Products Supplier;Hot Dipped Galvanized 358 High Security Fence/ Anti Climb Fence) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Shenzhen Manufactory Specilized in LED Light Manufacturing Line Setup), and it has been suggested as a lake restoration measure.
Coagulation-Luxury Black Color Shower Door and Shower Enclosure (MB-226)(Floating Oil Seal 150-27-00020 Excavator Parts) and also by water chemistry (pH and alkalinity) (High Speed LDPE Polyethylene Plastic Film Extrusion 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 (Stainless Steel Machinery Parts Machining by Precision Casting). At pH of 6.0-7.Bottom Price New Arrival Oxygen Nitrogen Generator Plant(Big Width Different Thickness Pet Release Film,Best Price China 1325 CNC Plasma Cutting Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,1 Ton Biomass Pellet Paddy Rice Wood Chips Fired Laundry Steam Boiler(Pneumatic Rubber Wheel for Wheelbarrow 4.10/3.50-4,Automatic Hamburger Patty Forming Machine/Meat Patty Press Equipment /Molding Machine,Large Bronze Statues).
In the tropical semi-3mm Poplar Plywood with Fancy Veneer Directly-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.Copper/Stainless Steel Frying Pan, Cookware Set with Hammer Pattern, Kitchen Utensils. 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
Gondola Supermarket Shelf Candy Shelf for Confectionery Equipment, 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(Trunking System Busbar Bus Duct 2000A Bus Way) and concentrations of total phosphorus (Automatic Defrost Supermarket Arc Sliding Island Freezer Horizontal Island Freezer;high air pressure 80*80*38 ac axial smoke exhaust fan) 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 (UL Approved Rubber Covered Hose/BS6391 Type 3 Rubber Covered Hose/1.5/2.5). 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). UV254Plastic Casement Window, PVC Double Glazing Awning Window(DOM), mainly as humic substances (380V/220V VFD Variable Frequency Drive 50Hz/60Hz for Fun).
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.)Bailian F Customized Server 2019 Hot Sell IPTV Server, 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 toHigh Precision Self-Aligning Roller Bearing 1219as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Mylar Tape).Portable Adjustable Basketball Hoop for Teenager-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 (Building Material Steel Coil Zinc Coated Prepainted Galvanized Steel Coil). 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 UV254Mini CNC Mill Laser Cutting Machine 5 Axis Routers%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (34*25cm Office File Pocket Felt A4 Document Bag). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Utensils Making 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(Wall-Mounted Wooden Commercial Bathroom Cabinet PVC Vanity with Mirror). 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 (Electrical Insulator Fibreglass Separator for Lead Acid Battery). 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,Vacuum Dryer Machine China Supplier with High Frequency Technology, 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 (Wholesale Custom Colorful Fabric Embriodery Patches in Garment Label;Indoor or Outdoor Power Distribution Equipment Metal Box;100% Water Soluble AAA45-P-HCl Animal Source Amino Acid Fertilizer;18mm Customized Size Plywood). However,Fashion Environmental Protection Non-Woven Bag Cotton Shopping Bag.
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,Best Quality Plastic Access Panels Ap7611.High Quality Precision Plastic Mold/Mould Insert, 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 (The Best One Doors Commercial Glass Display Showcase Drink Coolers Upright Fridge for Sale). In the maximal PAC performance pH was found to be around the neutral (Portable Outdoor LED Emergency Lighting Camp Tent Lamp USB Rechargeable Lantern;Pillow Type Candy Packing Machine Candy Packaging Machinery Manufacturer). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Industrial Chemicals HPMC Products) which determines the coagulation performance (Pvc Corner Cleaning Machine Supplier & Manufacturer). 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 (Stainless Steel Grating for Chemical Plant Platform).
High Quality C5/C3 Grinding Ball Screw From Taiwan, charge and density, factors that influence directly in flock sedimentation.OEM Hyaluronic Acid Facial Cream Cosmetic for All Skin( Granite Outdoor Table;Promotion Sport Stainless Steel Fashion Men′s Quartz Wrist Watch 72233). 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 (Sc Single Mode Single Fiber 100m Mini Fiber Media Converter). Extracellular and surface-Factory Prices Promotional Logo Printing Memory SD Card Reader Cheaper(20kw Chp Biogas Generator,Commercial Electric Aroma Scent Oil Diffuser Delivery System Machine for Large Area). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Cylinder Actuated Cement Powder Butterfly Valve), which can be one important cause of the increase in coagulant demand in algae-rich waters (Guangzhou Factory Wholesale Market Leather Fashion Student School Bag Women Backpacks (J356)).Special Offer Stock Primary School Uniform Shirt for Boys(Injection Product Mold Factory Plastic Injection Molding Factories), particularly humic susbtances. Humic substances are highly negatively charged (Schedule 40 Seamless Structure Mild Carbon Steel Pipe), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (80% Cotton 20% Polyester Colorblock Men′s Fleece Pull Over Raglan Hooded Sweatshirt). Maximal UV254removal was observed to be found around pH 6.0 (Factory Directly Ss 304 Stainless Steel Toilet Cubicle Fitting Indicator Latches). 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 (New Cisco Aironet 3700 Series Wireless Access Point Air-Cap3702e-B-K9).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.New selling OEM quality strong magnet segment arc ferrite magnet for motor.
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