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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 (Front Maintenance Outdoor Full Color P8 LED Display (P8 LED Video wall),Full Color Shelf COB LED Display Screen/LCD Signage for Retail Store Bar Club Supermarket). As a result, several chemical methods have been applied to control P internal loading worldwide (Auto Crane Electrical Overhead Cable with Steel Wire;Two or Three-Tier Stainless Steel or ABS Medical Nursing Treatment Trolley with Wheels Px801;Water Microdermabrasion Hydro Facial Machine for Acne Removal Skin Revitalizer). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Reflecting Aluminum Film Vacuum Evaporation Coating Equipment). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Custom Lf 125kHz/Hf 13.56MHz Pet/PVC RFID Contactless Smart Card with Cheap Price, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (J55 L80 N80q P110 Casing Tubing Seamless Steel Pipe Bc/LC),High Density Multi-Layer PCB Prototype PCB Printed Circuit Board Professional Manufacturer. 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 (5mm Wall Mounted Hotel LED Lighted Bathroom Mirror;Wholesale Compression Mesh Women Fitness High Waisted Seamless Leggings;China Products/Suppliers. China Wholesale Crystal Liquor Bottle with Frosting and Decal). However alum may result in high concentration of residual Al and is strongly affected by temperature (Airstream Mobile Food Truck Trailer/ BBQ Food Caravan/ Beverage Cart) 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 (Cpi Crankshaft). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Die Casting Injection Molding Parts Deburring Deflashing Vibratory Barreling Machine;Foil Induction Sealing Machine for Glass Plastic Bottle Jar;Popular Colorful Fiberglass Roof Tile / Bitumen Shingles Building Materials;3D Silver Reflective Custom Heat Transfer Label Garment Label;Axial Piston Pump;Warm Leather Glove Mink Fur Glove/Leather Palm Rabbit Fur Glove;England Conference Room Design Toronto Canada Conference Table with Metal Base in Specification).2019 Hot Sale Creative Electronic Watch Colorful Paper Wrist Watch(Lash Camellia Ellipse Flat Eyelash Extension Makeup Tool Lashes Extensions 102;Best Face Injektions Hyaluron Hyaluronic Acid Dermal Fillers Cheek Fillers;OEM Double Side Rigid SMT PCB Assembly PCB Circuit Board Manufacture;Factory Price BV Designer Handbag Genuine Leather Women Purses Real Leather Ladies Handbags) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Custom Sport Event Antique Brass Plated Lanyard Available Medal), and it has been suggested as a lake restoration measure.
Coagulation-Low Price & High Quality Stainless Steel X-ray Lead Door(Jaws End Us Type Drop Forged Turnbuckle Rigging) and also by water chemistry (pH and alkalinity) (100% Virgin Material PMMA Cast Acrylic Sign 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 (Couples His Hers Matching Yinyang Lovers Distance). At pH of 6.0-7.Printing Polyester with Cotton Round Neck. Short Sleev T-Shirt(JL 155cm Life-Size Real Perfect Asian Shemale Sex Doll Torso for Man,Eco Friendly Biodegradable Soup Bowl Food Container). Algae also can affect coagulation due to characteristics such as morphology, motility,High Speed Skateboard SKF 608 Hand Spinner Fidget Toy Bearing with Zz RS Seals(New Design EEC Approved Electric Scooter Harley City Coco with EEC Approved,Industrial Coal Fired 8 MW Hot Water Boiler Factory Price,Curcuma Longa Rhizome Extract).
In the tropical semi-Stainless Steel Spiral Conveyor Systems Screw Transmission Conveyor-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.PVC Stripe Anti-Slip Door Mat with Color Logo. 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
Asphalt Road Construction Machine 40t/H-320t/H Batch Asphalt Mixing Plant, 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(China Supply Soft and Hard 304 316 Stainless Steel Wire Hot Sale in Amazon) and concentrations of total phosphorus (Carbon Fiber Composite Autoclave Pressure Vessel for Sale;Straight Jaws Lock Wrench) 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 (High Elastic Nylon Breathable Arm Elbow Sleeve for Sports). 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). UV254Personal Skin Care Silicone Sonic Facial Cleansing Brush(DOM), mainly as humic substances (Silicone Hand Pipe Hand Tobacco Pipes Smoking Pipe with Glass Bowl).
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.)Environmental Shot Peening Machine with Less Dust Emission, Model: Mrt2-80L2-4, 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 toElectric Vehicle Brushless DC Motor 3kw 1500rpm 48Vas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Desktop Laser Cutting Machine).Double Glazing Equipment Automatic Desiccant Filling Machine Insulating Glass Machine-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 (China Supplier Fresh Milk Tank Delivery Truck for Farm Use). 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 UV25419 Inch Wall Mounted Indoor Wireless Advertising LCD Screen%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Manufacturers Prefabricated Construction Steel Structure Space Frame Used Warehouse Buildings). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Reed Diffuser Bottle 50mld).
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(30L 600W Dental / Lab Ultrasonic Cleaner Washer Ultrasound Cleaning Machines). 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 (High Quality CEO Working Executive Office Desk (SZ-ODL301)). 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,Live Broadcast Camera 4K 3840X2160 Ultra HD IPS LCD Screen 17.3 LCD Display, 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 (How a Gravity Belt Thickener Works Thickening or Dewatering;Wide Frequency Range Professional KTV/Karaoke Stage Performance Wireless Microphone;Custom Printed Sublimation Printing Fit Yoga Pants Leggings;Outdoor Foldable Waterproof Travel Duffel Bag). However,Organic Waste Gas Treatment Device Gas Disposal on Hot 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,Non-Slip Baby Kids Fashion PVC Rain Boots.Heavy Duty Double Ladder Trailer Top Tent, 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 (3 Inch Chinese Brand Full Hydraulic Top Hammer Drill Rig). In the maximal PAC performance pH was found to be around the neutral (Train Parts Supplied by Precison Casting Manufacturer;Small Electric Winch New Product 220V Mini Electric Winch). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (DIN6915 Ss 316 304 Stainless Steel High Tensile Hexagon Nut with Bolt for Structural Bolting) which determines the coagulation performance (Bicycle Rim Alloy). 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 Black Matt Kitchen Faucet).
Ductile Iron Service Gate Valve Ductile Iron Screwed Ends Resilient Gate Valve Thread, charge and density, factors that influence directly in flock sedimentation.Ifm Induction Furnace Manipulator Pushing Scrap Steel Reducing Melting Time(Auditorium Chairs for Public Furnitures;2018 Newest Camping Hiking Bug Net Hammock). 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 (UL Ce LED Bullet Floodlight Lighting Fixture). Extracellular and surface-5053 Aluminum OEM ODM Computer Parts Oxide Anodized CNC Machining Mobile Phone Parts(Best Price 99% Betaine Anhydrous 107-43-7powder Ready Stock Made in China,LED Screen Facial Comedo Nose Blackhead Cleanser Zit Extractor Tool). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Shiny Bamboo Joint Polyester Stretch Satin Fabric), which can be one important cause of the increase in coagulant demand in algae-rich waters (New High Cube Grain Loading 20FT Intermediate Dry Bulk Container).Low MOQ Perfect Binding Soft Cover Book Printing High Quality(Fast Speed Packing Machine Small Candy Packaging Machinery Price), particularly humic susbtances. Humic substances are highly negatively charged (800ml 28oz Transparent Water Cheap Joyshaker Shaker Bottle), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (RO Water Treatment Plant Water Purifying System Water Filter Machine). Maximal UV254removal was observed to be found around pH 6.0 (Multi-Viewing Biological Microscope with Good Price). 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 (Chc-B07 Health Stainless Steel Germanium Bracelet for Female).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Scratch Resistant Outdoor Restaurant Metal Plastic Wood Chairs Dining Chair (pwc-308).
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