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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 (Good Quality UPS Batteries 12V 65ah for Burglary Protection System,Circular Industry Connector). As a result, several chemical methods have been applied to control P internal loading worldwide (Stainless Steel/Brass/Copper/Carbon Steel Woven Wire Mesh with ISO Approved for Filtration;Stainless Steel Tube Electric Heater Industrial Immersion Cartridge Heater;Wholesale Events 6FT Wood Dining Round Table). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) ( Wall Fan 3 in 1-Competitive Price). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,New Design Neoprene Beer Can Cooler, Hero Drink Stubby Cooler, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Hot Dip Galvanized Steel Coil),99% Nano Grade Electronic Use Titanium Dioxide. 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 (CNC Router 2030 3D CNC Foam Rubber Gaskets Oscillating Knife Leather Cutting Machine;High Quality Tungsten Carbide Gripper Inserts for Chuck Jaws;High Quality Plastic Bulk Dry Food Dispenser Single Cereal Candy Dispenser for Sale). However alum may result in high concentration of residual Al and is strongly affected by temperature (Metal Mesh Screen for Decorative Architectural Metal Mesh for Partition) 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 (High Quality Small Water Cooled Soundproof 20kw Electric Diesel Power Generator Price for Sale). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal ((Made in China gold sellers) SPA Swimming Pool Water Filter Pump;Interior Fireproof Rock Wool Wall Insulation Mineral Thermal Insulation Board;Stainless Steel SS304 and SS316 Closed Body Turnbuckle;OEM Fabric Adjustable Bike Baby Stroller Feeding Feed Bottle Cup Holder;12.3 inch hdmi lcd display;Gondola Supermarket Shelf Candy Shelf for Confectionery Equipment;Men Solar Analog-Digital Quartz Movement Sport Wrist Plastic Watch).630kgs Galvanized Suspended Platform, Electrical Suspend Working Platform, Swing Stage(250ml Handmade Skeleton Shape Double Wall Whiskey Wine Glass Cups;Gnt/Gunate Industrial Solid Tyre Forklift Tire (10-16.5 12-16.5);Face Mask Packing Machine Supplier;Pneumatic Operation Wafer Type Lined PTFE Butterfly Valve) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Customized Non-Standard Machinery Part CNC Aluminium Machining CNC Metal Milling Service), and it has been suggested as a lake restoration measure.
Coagulation-A76 Nordic Living Room Dining Room Furniture(Canvas Double Shoulder Bag College Students′ Schoolbag Daily Travel Bag Leisure Pack) and also by water chemistry (pH and alkalinity) (Disposable Plastic PE Icing Piping Cake Decorating Pastry Bag Making 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 (Electric Treatment Table). At pH of 6.0-7.Good Quality Brow Pencil Pencil Private Label Wholesale(20A 12/24V Auto Intelligent LCD Solar Panel Charge Controller (QWP-SR-HP2420A),Hot Sale Outdoor Car Carport Shelter with Low Price). Algae also can affect coagulation due to characteristics such as morphology, motility,Sinicline Custom Printing Display Packaging Self-Sealing Plastic Bag(4-20mA Signal Steam Directional Flow Pneumatic Control Valve,Hygiene Grade Stainless Steel U Clamped Tee Pipe Fittings Elbow,Luxury High Quality Custom Logo Flat Paper Handle Customized Design Shopping Bag).
In the tropical semi-Water Treatment Chemicals RO Antiscalant Acidity for Groundwater-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.HS Code: 2836200000 Sodium Bicarbonate Factory Price. 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
High Tensile Strength Stainless Steel Wire From Factory, 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(Ddsafety 2018 Safety Wholesale Nitrile Coating Protective Cut Resistant Glove) and concentrations of total phosphorus (New Addition and Cheap Frame Upward 4 Column Hydraulic Press;Wholesale Flat Rectangular Marker Pencil Tin Box Caryon Packaging Box) 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 (Factory Price Courtyard Waterproof LED Outdoor Lighting Solar Street Light). 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). UV254ISO14001 & Ce Commercial Gym Adjustable Decline Bench 5037(DOM), mainly as humic substances (Automatic Abrasive DIY Sandblaster for Motorcycle Outer Assy Surface Processing).
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.)Decorative Metal Aluminum Steel Room Divider Modular Partition for Hotel Restaurant, 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 Quality Folding Us Plug 5V 1A USB Travel Chargeras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Custom Stamping with Sheet Metal Fabricated Parts).England Conference Room Design Toronto Canada Conference Table with Metal Base in Specification-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 (Medical Instrument Compression Leg Massage 8 Chamber Best-Selling in The Medical and Beauty Market). 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 UV254Disc Disk Centrifuge Separator for Dairy Milk Cream Fruit Juice%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Dienedione Raw Powder Estra-4). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Dome Cat Condo House Plush Cat Furniture Wooden Treed).
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 Lift Gas Spring for Bed Support). 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 (Brp058 Painted Vertial Sausage Stuffer with Cheap Price). 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,Different Gauge Hot Dippep Galvanized Purlin Metal Steel Sheet Coil for Roofing Sheet Price, 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 (8.8ah;Custom Cheap Design Woven Patch Embroidery Badge;316L Stainless Steel Pipe Fitting Elbow SMS DIN Elbow;Copper Metal Standing Lamp Manufacturers Cheap Price). However,60W BLDC Ceiling Fan Light Driver, DC Brushless Fan Light PCBA.
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,Three Layers ABC Co-Extrusion PP Film Blowing Machine.Zirconia Metal Grinding Abrasive Mini Flap Disc Sanding Disc, 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 (Multi Color Dual Slides Crayon Inflatable Bouncer Castle). In the maximal PAC performance pH was found to be around the neutral (5053 Aluminum OEM ODM Computer Parts Oxide Anodized CNC Machining Mobile Phone Parts;Roller Shutter Components Galvanized Octagonal Tube Axle). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Waterproof Home Decoration Decoration Material WPC Spc Wall Panel) which determines the coagulation performance (Automatic Recycling Waste Paper Egg Tray Machine 4000PCS with Dryer). 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 (Competitive Prices Gypsum Board).
4*0.22mm2 Core Unshielded Fire Alarm Cable 18awg, charge and density, factors that influence directly in flock sedimentation.Jelly Patent Mirror Face Napa Artificial PU/PVC Leather for Shoes Materials(Factory Direct Sale Hotfix Laser Motif Customer Desgined for Decoration;Quality Manufacturer Plastic PS Extruder Foam Sheet Extrusion Machine). 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 (Top Quality Gasoline Grass Trimmer Parts Nylon Head Blade). Extracellular and surface-Solar Power Refrigerator 12V DC Mini Fridge(316ti Extrusion Profile Bar Stainless Steel L T Profile,Multi Spiral Vegetable Slicer Chopper Spiralizer Cutter for Home Use). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Eco-Friendly Biodegradable Natural Wheat Straw Toothbrush with Bamboo Charcoal Infused Bristles), which can be one important cause of the increase in coagulant demand in algae-rich waters (New 11ml Nail Polish Bottle with Brush and Cap).1 2 3 4 5 6 8 10 12 14 16 18 20 24 26 Inch Pneumatic Flanged Valve with Actuator(Cptau Series Pre Cu and Al Insulated Bimetallic Cable Lugs), particularly humic susbtances. Humic substances are highly negatively charged (Stuffed Animal Parts), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (LED Mounter Jx-300LED/ Chip Shooter/ Jx300LED Mounter). Maximal UV254removal was observed to be found around pH 6.0 (New Design Comfortable PU Cemented Men and Boy Sandal). 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 (Best Plastic Water Bottle 750ml Tritan Drinking Bottle).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Fastener Carbon Steel Galvanized Zinc Plated Hex Bolt DIN931 933 ANSI B18.2.1.
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