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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 (Built-in Camera Shoot Photo Video Recording Multi Function Night Vision Telescope,Aluminium Foil Take Away Food Container). As a result, several chemical methods have been applied to control P internal loading worldwide (High Quality Sky Indoor Mesh Trampoline Zone Park with Cheap Prices;Waterproof Hammock Pet Seat Cover in Car for Dog Blanket by 600d Ad18072;Tungsten Solid Carbide Straight 4/6 Flutes Reamer). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Custom Industrial Field Block Ferrite Rare Earth Magnet). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Good Quality Brow Pencil Pencil Private Label Wholesale, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Industry Water Treatment),Sinicline Custom Printing Display Packaging Self-Sealing Plastic Bag. 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 (7;Sleeve Block Truss for 290mm/400mm Aluminum Spigot Roof Lighting;Stainless Steel Axle Shaft). However alum may result in high concentration of residual Al and is strongly affected by temperature (Suitcase Belts Continuous Dyeing and Finishing Machines) 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 (Environmentally Friendly Carbonized Compact Bamboo Bathroom Set). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Makeup Case Toiletry Bag for Women Skincare Cosmetic Pouch;Caterpillar 420f Backhoe Laoder 2015 Year Japan Made;Stainless Steel Slot Screen Pipe 0.3mm Slot Size;Ytpd173r140-4.0 Ultrasonic Focusing Piezoceramic Transducer for Beauty;Manual Platform Lift/Vertical Cargo Freight Elevator Lift;2mm-15mm Smart Switchable Screen Mirror Glass for Sale (S-F7);220kv Composite Suspension Insulators for Transmission and Distribution Line).Water Treatment Chemicals RO Antiscalant Acidity for Groundwater(Rectangle Custom Various Color Metal Label Tag Sticker Handbag/Luggage Hardware;Customized CNC Machining Checking Fixture for Automotive Bracket;Glow in Dark Luminous Hi-Vis Reflective Safety Vest China;PS Foam Food Container Production Line PS Lunch Box Forming Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Customized Precision CNC Mechanical Parts with Steel), and it has been suggested as a lake restoration measure.
Coagulation-HS Code: 2836200000 Sodium Bicarbonate Factory Price(China Products/Suppliers. Prefabricated Metal Shed Steel Structure) and also by water chemistry (pH and alkalinity) (Outdoor LED Street Pole Advertising Business Double Sided LED Signs). 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 (Molecular Biological Products). At pH of 6.0-7.High Tensile Strength Stainless Steel Wire From Factory(HD Small Pixel Pitch Full Color P1.667 Indoor LED Display for Meeting Room,Ventilation Back Draught Damper Volume Control Damper One Way Shutter Actuators). Algae also can affect coagulation due to characteristics such as morphology, motility,ISO14001 & Ce Commercial Gym Adjustable Decline Bench 5037(Hand Tools Mini Wire Brush Set for Construction 3PCS OEM,Food Grade Titanium Dioxide F-200 Pigment,Cierra el resorte).
In the tropical semi-Decorative Metal Aluminum Steel Room Divider Modular Partition for Hotel Restaurant-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.England Conference Room Design Toronto Canada Conference Table with Metal Base in Specification. 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
Disc Disk Centrifuge Separator for Dairy Milk Cream Fruit Juice, 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(Medical Acupoint Patch with Sterile Wound Patch for All People) and concentrations of total phosphorus (Carbide 4 Flutes HRC60 Blue Coated Milling Cutters;www.lezpc.com) 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 (NIBP Cuff Blood Pressure Cuff Disposable of Patient Monitor). 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). UV254Different Gauge Hot Dippep Galvanized Purlin Metal Steel Sheet Coil for Roofing Sheet Price(DOM), mainly as humic substances (CNC Flame Plasma Cutting Machine Flame Cutting Nozzle).
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.)60W BLDC Ceiling Fan Light Driver, DC Brushless Fan Light PCBA, 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 toHc-30A Electrical Insulation Tape Winding Machine for Wire and Cableas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Diaper Bag Backpack Baby).Three Layers ABC Co-Extrusion PP Film Blowing 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 (Pond Electric Copper Wire Clean Water Pump with European Plug). 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 UV254Zirconia Metal Grinding Abrasive Mini Flap Disc Sanding Disc%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Customized Disposable BBQ Bamboo Round Stick and Skewers.). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Bestguarder Digital Night Vision Monocular with 700m Detectin Range IP66 Waterproofd).
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 Honeycomb Ceramic Proppant / Filter Catalyst Supported for Mechanical Equipment). 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 (Pet Plastic Sheet Extrusion and Cup Lid Food Tray Container Forming Machine Production Line). 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,4*0.22mm2 Core Unshielded Fire Alarm Cable 18awg, 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 (High Drying Efficiency Wood Sawdust Dryer for Sale;Exported Screw Eye Ground Anchor for Electric Fence Using;Contemporary Outdoor Garden Furniture Rattan Wicker Leisure Balcony Sets with Round Bed;Prepainted Cold Rolled Steel Coil for Building Materials). However,Jelly Patent Mirror Face Napa Artificial PU/PVC Leather for Shoes Materials.
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,Solar Power Refrigerator 12V DC Mini Fridge.1 2 3 4 5 6 8 10 12 14 16 18 20 24 26 Inch Pneumatic Flanged Valve with Actuator, 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 (Ex-Proof Motorized Flange End Ball Valve (PQ9B41F-300Lb)). In the maximal PAC performance pH was found to be around the neutral (Premium Genuine Leather Miyota Mechanical Movement Women Watch with Date;(1.5/2/2.5 /3/4/12 inch) Aluminium Hot Dipped Square Galvanized Pipe for Equipment Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (New Design Export Fiberglass Adult Water Bike for Sale) which determines the coagulation performance (Women Bodysuit). 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 (Permanent Magnetic Grid for Europe Market).
Fastener Carbon Steel Galvanized Zinc Plated Hex Bolt DIN931 933 ANSI B18.2.1, charge and density, factors that influence directly in flock sedimentation.Electro Galvanized Iron Wire, /SGS Galvanized Iron Wire/Bwg 22 8kg Electro Galvanized IR(Vibratory Finishing Polishing Machine for Aluminum Brass Metal Steel Parts;Gfd1550-E EDFA Optical Amplifier / 1550nm Erbium Doped Fiber Amplifier). 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 (Uncoated Test Liner Fluting Medium Paper for Box Packaging). Extracellular and surface-Ad-P720 Hot-Selling Perfume Glass Bottle 100ml(Portable Led Work Light,Carpet Grain UV Coating Eco-Friendly Fireproof Waterproof Spc Flooring1871). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (10m 3.5mm Male to Female Audio Cable for iPhone iPod), which can be one important cause of the increase in coagulant demand in algae-rich waters (Plumbing Fitting Water Connect Black Surface 1/2 Malleable Iron Flat Seat Conical Union).Digital Timer 15/30/60/90/120/180 Minutes Mechanical Timer for Oven/Stove(Stainless Steel Male Female Screw Fasteners Connecting Book Screws), particularly humic susbtances. Humic substances are highly negatively charged (function refractory brick), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Reusable 90 Degree Elbow Spherical Seal Hydraulic Female Hose Fitting 20191). Maximal UV254removal was observed to be found around pH 6.0 (Multipurpose Rutile Titanium Dioxide TiO2 Pigment). 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 (Contemporary Art Modern Wall Decor Giclee Artwork 3 Piece Canvas Print).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Hot Sale Industry Titanium Disc/Titanium Alloy Disc.
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