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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 (Ferrite Magnet Used in Motor as Magnetic Strip,Agricultural Parts L Type Rotary Tiller Blade Wholesaler Quotes & PriceList). As a result, several chemical methods have been applied to control P internal loading worldwide (Three Lines Production Three Side Seal Pouch Making Machine;Cement Roofing Sheets Pigment Yellow Iron Oxide Prices;Oversized Canvas Travel Tote Luggage Weekend Duffel Bag). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Air Cooler Skin Cooler Zimmer Cryo Skin Cooling Device). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Precision CNC Auto Spare Machinery Parts for Car-Mounted Mobile Power Bank, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (List Of Locksmith Tools),Factory Price BV Designer Handbag Genuine Leather Women Purses Real Leather Ladies Handbags. 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 (Multi-Functional Heat Reflux Ethanol Extraction and Concentration Equipment 200L for Herb;New Design Customized Juice Beverage Canning Machine;EPS Sandwich Panel Forming Machine Production Line with High Quality). However alum may result in high concentration of residual Al and is strongly affected by temperature (PCBA Indutrial Control Assmebly Quick Turn PCB Assembly) 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 (cnmirant). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Garden Metal Natural Rusty Flower Decoration Product;8FT Wood Log Debarker Machine for Plywood Machinery;Aluminium Foil Cup Lids Metal Stamping Parts/Deep Drawing Parts;China Magic Panel Matrix 36X15W Single LED Controllable LED Beam Moving Head Light;Waterproof Picnic Beer Can Ice Cooler Bag;2 Storey Worker Living Block Container House Supplier;Waterproof and Moldproof Marble Floor Grouting).Tsudakoma Zax-N Air Jet Looms Year 2007 210 Cm 2861 Dobby Weaving Textile Machinery(Colourful Carbonless Paper NCR Printing Paper 50GSM/55GSM;Qgd Series 3 Inch Deep-Well Submersible Electric Screw Water Pump;Advertising Outdoor Display;Hex Phillips Torx Slotted Bits Ratchet Hand Screwdriver Sets) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Custom Outdoor Event Pop up Canopy Easy up Advertising Tent), and it has been suggested as a lake restoration measure.
Coagulation-5mm Wall Mounted Hotel LED Lighted Bathroom Mirror(High Quality Folding Training Study Table with Wheels Sf-10f) and also by water chemistry (pH and alkalinity) (Glow in The Dark Pigment Luminescent Luminous Powder). 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 (Textured Paint Exterior Concrete Walls). At pH of 6.0-7.Best 1.75mm 3mm ABS PLA 3D Printer Filament Supplier 1kg 5kg for 3D Printing Clear ABS Filament(Custom Personalized Logos Cheap Neck Printed Custom Polyester Lanyards Ribbons with ID Card Holder,Wear Resistant Steel with Hardness 58-62 HRC). Algae also can affect coagulation due to characteristics such as morphology, motility,China Wholesale Hot Sale Microfiber Car Cleaning Towel(Korea Glittery Heat Transfer Film /Vinyl for Clothes/T-Shirt Printing Cdg-16 Light Multi,Popular Selling Sausage Casing Making Machine,500w Electric Scooter).
In the tropical semi-530ml Glass Drinking Water Bottle with Silicone Sleeve&Handle Lid-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.Cylinder Borosilicate Glass Cooking Oil Bottle with Spout. 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
11oz Heat Transfer Sublimation Hot Water Change Color Magic Mug (Matte), 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(Good Sale Lfc Sand Preparation and Casting Molding Line) and concentrations of total phosphorus (Vegetable Herb Garden Hand Tools with Storage Box;Bearing 607 2rs) 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 (Wholesale Factory Prices Ceramic Hair Curler Magic Hair Curler). 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). UV254Hot Selling SAA Rcm Listed CCT Changeable LED Down Light(DOM), mainly as humic substances (Decorative Metal Aluminum Steel Room Divider Modular Partition for Hotel Restaurant).
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.)Ferrous Sulphate Heptahydrate for Water Treatment, 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 toWaterproof Hammock Pet Seat Cover in Car for Dog Blanket by 600d Ad18072as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Airport X Ray Scanner).Factory Made Pneumatic Adjustable Gas Piston 600n for Garden Chair-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 (7). 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 UV254NF3, Nitrogen Trifluoride, Liquid Gas, 99.99~99.999%%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Sleeve Block Truss for 290mm/400mm Aluminum Spigot Roof Lighting). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Zxm-La522 Glass Straight Line Edging Machine with Diamond Cup Wheelsd).
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(Suitcase Belts Continuous Dyeing and Finishing 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 (Makeup Case Toiletry Bag for Women Skincare Cosmetic Pouch). 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,Recoil Steel Hot Coiled Extension Coil Compression Heavy Duty Spring, 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 (Ytpd173r140-4.0 Ultrasonic Focusing Piezoceramic Transducer for Beauty;2mm-15mm Smart Switchable Screen Mirror Glass for Sale (S-F7);220kv Composite Suspension Insulators for Transmission and Distribution Line;Cow Leather Glove). However,Colorful Commercial PVC Vinyl Flooring for Office.
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,Microblading Supplies Private Label Disposable Tattoo Pen Eyebrow Manual Pen with Blades.Nordic Creative Barstool High Foot Chair Modern Minimalist Cafe Counter Seat Restaurant Home, 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 (Rectangle Custom Various Color Metal Label Tag Sticker Handbag/Luggage Hardware). In the maximal PAC performance pH was found to be around the neutral (Customized CNC Machining Checking Fixture for Automotive Bracket;PS Foam Food Container Production Line PS Lunch Box Forming Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Customized Precision CNC Mechanical Parts with Steel) which determines the coagulation performance (25kg/Bag Pigments Chrome Green Colors). 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 (China Products/Suppliers. Prefabricated Metal Shed Steel Structure).
Strong BOPP Laminated 25kg 50kg Rice Polypropylene Sack, charge and density, factors that influence directly in flock sedimentation.Cg125 Motorcycle Parts Metal Motorcycle Foot Kickstand Side Stand Spring(Outdoor LED Street Pole Advertising Business Double Sided LED Signs;HD Small Pixel Pitch Full Color P1.667 Indoor LED Display for Meeting Room). 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 (Ventilation Back Draught Damper Volume Control Damper One Way Shutter Actuators). Extracellular and surface-Seamless Circular/Square/Rectangular Steel Tube(www.cnbdlift.com,Hand Tools Mini Wire Brush Set for Construction 3PCS OEM). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Food Grade Titanium Dioxide F-200 Pigment), which can be one important cause of the increase in coagulant demand in algae-rich waters (Silicone Rubber Pin Insulator/Polymer Composite Insulator (10kv-33kv)).Construction Equipment 1.5 Cube Materials Portable Concrete Mixer(Customized Waterproof Backpack Canvas Laptop Bag), particularly humic susbtances. Humic substances are highly negatively charged (Avss Wire and 4 Pin Tyco Connector Automotive Wire Cable Harness), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Medical Acupoint Patch with Sterile Wound Patch for All People). Maximal UV254removal was observed to be found around pH 6.0 (Carbide 4 Flutes HRC60 Blue Coated Milling Cutters). 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 (Lockey Loto Durable Standard Safety Gate Valve Lockout with Ce).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Construction Product Metal Steel Galvanized Flooring Deck for Wholesaler.
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