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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 (High Chrome Cast Iron Ball Forged Steel Ball Grinding Media,Dia. 35mm Abl Tube Suppliers Cream Packaging Tube). As a result, several chemical methods have been applied to control P internal loading worldwide (Stainless Steel Welded Woven Metal Wire Mesh Basket for Filter;Factory Price Luxury Autism Heavy Duty Weighted Mink Blanket;Household Thermometer Electronic Temperature and Humidity Meter Monitor). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (4.5qt Camping Nonstick Wholesale Cast Iron Dutch Oven Bread Pan). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,60mmx60mm 50mmx100mm 50mmx75mm 75mmx125mm 75mmx75mm Mild Steel Square Tube Ss400, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (EVA Houseware Fridge Mat),Hot Sale Brass Chrome Metal Dish Toilet Bathroom Fitting. 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 (Tractor Trailer Cable Truck 7 Core Spiral Coiled Electric Cable for Tractor & Trailer;9000-12000 BTU Air Conditioning /Cabinet Air Conditioner for Marine;Twist Lock Power Cord). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hyaluronic Acid Gel Microneedling Device for Meso Serum Mesotherapy Solution) 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 (Film Sanitary Shoes Cover Dispenser Machine Sticky). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Indoor HD LED Sign Board for Advertising LED Display Screen;Automatic Packaging Filling Machine for Concentrated Liquid Detergent Pod; with Windproof;Food Grade Biodegradable Stand up Pouch Kraft Paper Packaging Bag with Zipper;Professional Fishing Equipment Carbon Pole Rod for Sale;Manufacture Tempered Glass Door Stainless Steel Curved Bottom Patch Fitting;New Design Hot DIP Galvanized Pig Gestation Stall).Denso Nozzle G3s32 for 295050-056#1465A351 Common Rail Injector System(High-Class Leather Cover Business Agenda Organizer Planner Notebook;High Strength PVC Foam Board for Building Materials;Best Selling Cheap Factory Direct Classic Style Bed Fitted Sheet;Custom Foldable Storage Basket with Metal Handle and Lid) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Customized Normal Temperature Feed Channel Cylinder for Stacker Reclaimer), and it has been suggested as a lake restoration measure.
Coagulation-Wholesale Custom Logo Printed Chocolate Candy Box(Professional Mechanism Hydraulic Oil Headrest for Barber Chair) and also by water chemistry (pH and alkalinity) (Terex Cone Crusher Spare Parts Concave Mantle and Bowl Liner). 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 (Metal Snap On Button). At pH of 6.0-7.Custom Wedding Music Video Brochure Box Gift Ring Jewelry Box with LCD(Adjustable Folding Infant Feeding Baby Highchair,THK Misumi Hiwin Linear Ball Bearing Block Bearing Gl25ca). Algae also can affect coagulation due to characteristics such as morphology, motility,Floating 8-12mm HDF Class 32 Waxed Waterproof Oak Wood Laminate Flooring(Disc Neodymium N35 N45 N40 N42 N38 N48 N52,Factory Price 304 304L 316 316L 321 Inox Stainless Steel Coil / Sheet / Plate,Heavy Duty Rack Supported Steel Panel Mezzanine for Warehouse with ISO/SGS).
In the tropical semi-LED Car Work Light of 51W 6inch with off-Road Spot Beam-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.Long Using Time Rechargeable Cordless Hair Clipper. 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
Water Oil Liquid Level Measurement Devices Glass Level Gauge, 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(Small Silent Biogas Electric Generator for Biogas Plant) and concentrations of total phosphorus (Factory Ultrasonic Herb Solvent Extraction Equipment with Discount;En124 D400 Medium Duty Ductile Iron Manhole Covers Mould) 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 (Ktz Series Best Slurry Pump Sewage Submersible Pump). 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). UV254Manufacturer Black Painting Seamless Carbon Steel Tube Hose Pipe(DOM), mainly as humic substances (High Quality Genuine Leather Luxury Casual Shoes Sneaker for Men Fashion Sneaker Shoes for Men).
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.)Small Electric Winch New Product 220V Mini Electric Winch, 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 Prefabricated High Rise Steel Structure Apartments Hotel Buildingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Corrugated Cardboard Sheet Cutting Machinery).Custom Clear Acrylic Chinese Tea Table (BTR-Q1012)-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 (Electronic Leak Detector Sf6 Gas Leak Detector So2 Analyzer). 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 UV254Ngk Spark Plug for BMW 7 12120037607 Bkr6equp Double Laser Platinum%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (ASTM A335 P11 Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (High Efficiency Scc206A Water-Based Green Cutting Fluid From Chinese Supplierd).
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(Best Factory Price Metallic Honor Medal with Neck Ribbon). 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 (Water Play Equipment Inflatable Gym Air Track Mat). 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,Vending Machine 12.1 Inch Embedded or Open Frame Capacitive Touch Screen Monitor, 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 (Wall Mounted Bathroom Tissue Holder Toilet Paper Towel Roll Holder;Colorful Glass Straw Drinking Straw Reusable Borosilicate Glass;Silicon Carbide Mechanical Seal with Excellent Corrosion Resistance;High Quality 50ohm Flexible PTFE Insulation Coaxial Cable Rg400). However,Small Portable Hand Cotton Picking Machine in India China Picking Cotton Machine.
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,Online Hot Sale 5 Tier Silver Home Organizer Shelving.Genuine Car Spare Auto Parts 48531-80581 for Shock Absorber, 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 (Hot High Quality Self Service Car Wash Equipment). In the maximal PAC performance pH was found to be around the neutral (Pedstal Electric Stand Fan 5 Speed Control Air Cooler;Manufacturers Sell Direct Bullet Design Red Hollow Crown Lipstick Tube). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (High Quality Asphalt Waterproof Emulsion Bitumen Emulsion Coating) which determines the coagulation performance (Universal Replacement Parts for Car Seat Headrest). 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 (Fashion Watch Factory Swiss Quartz Women Wrist Branded Watch (WY-001H)).
Replacement EPE Eppensteiner Filter Element (8260P10S000P), charge and density, factors that influence directly in flock sedimentation.Women′s Foam White Lettering-Print Cotton T-Shirt(Commercial Industrial Fast Food Chicken Electric Gas Pressure Deep Fryer for Mijiagao;20HP Copeland Scroll Compressor Zr250kce-Tw7-522). 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 (Prefab Prefabricated Lightweight Steel Structure Construction Processing Plant Metal Workshop). Extracellular and surface-Long Range Passive EPC Gen2 Monza Chip UHF RFID Wet Inlay(Bridge Opening Towline Plastic Towline Cable Drag Chain,Professional Industrial Cr-V Combination Plier for Cutting). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Pneumatic Air Fitting Female Straight for PU&PA Hose (Metric Size-R(PT) Thread Type)), which can be one important cause of the increase in coagulant demand in algae-rich waters (Women Footwear Ballerina Casual Shoes With High Quality).Factory Direct Sale Hotfix Laser Motif Customer Desgined for Decoration(250sv-Sp Mining Centrifugal Vertical Wet Slurry Pit Pumps), particularly humic susbtances. Humic substances are highly negatively charged (Dc Geared Motor), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (3*42mm Armoured NBR Sheathed Round Electric Submersible Oil Pump Power Cable). Maximal UV254removal was observed to be found around pH 6.0 (Fast Dry Sublimation Transfer Paper 100GSM 74inch for Polyester Printing). 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 ( Enginerring Machine).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Rubber Wheel Stopper Car Parking Blocks Rubber Speed Cushion.
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