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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 (New Design Neoprene Beer Can Cooler,Chiller Condensing Unit). As a result, several chemical methods have been applied to control P internal loading worldwide (Cheap Price Woodfree Offset Writing Printing Paper;High Quality XCMG Truck Mounted Crane Sq3.2sk1q/K2q in The Philippines;Two Upright Frame Steel Plate Warehouse Storage Light Duty Rack). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Custom Wall Hanging Flower & Plant Plastic Garden/ Nursery Pots). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Shanghai Port Adjustable Steel Hinge for Security Wooden Door, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Frameless Simple Beveled Bathroom Mirror with Good Price),High Quality Watermark Brass Square Bottle Trap in Gold. 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 (New TF Card Head Fone Retractable Audifonos PARA cellular Bluetooths Headphone;Fancy Corn Starch Disposable Round Plate with Stripe for Party;Ce Approved Disposable Blood Bag for Ozone Blood Therapy). However alum may result in high concentration of residual Al and is strongly affected by temperature (Coconut Shell Activated Carbon for Drinking Water Treatment) 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 (Tea Leaf Plucking Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (100ml Boston Round White Matte Plastic Pet Nursing Care Toner Bottle;Digital Pistol Safe Box / 4-Number Digital Safe Box;China Manufacturer Plastic Material Black Masterbatch PE PP Resin;Braided Nylon Aluminum Magnetic Micro USB Cable for Smart Phone;Electric Heat Hot Air Tea Moringa Leaf Herb Drying Machine;China Manufacturer Single Use Blue Hospital Reinforced Surgical Gown with Knitted Cuff;Hot Selling 30W Fractional CO2 Laser Vaginal Tightening Machine).PVC Edge Banding Printing Machine Tape Banding Machine Wire Banding Machine(Electronic Writing Board Finger Touch Infrared Interactive Board for Interactive Kids Games;Cmyk Printed Colorful Logo Wholesale Luxury Fancy Art Paper Shopping Gift Bag with Ribbon;Portable Permanent Hair Removal 808nm Diode Laser / Skin Laser Rejuvenation Machine;Ductile Iron Grooved Rigid/Flexible Couplings Fire Fighting Pipe Fittings) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Professional Effective Shockwave Belly Fat Removal Machine/ Shockwave Slimming), and it has been suggested as a lake restoration measure.
Coagulation-High Aluminum Insulating Ceramic Fiber Paper for Industrial Kilns(Horizontal Flat Bed CNC Metal Lathe (CAK6140 CAK6150)) and also by water chemistry (pH and alkalinity) (2019 LCD PRO Hot Ionic Straightening Brush (Q20)). 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 (Glass Plate 1 Gang Switch). At pH of 6.0-7.Bookcase Solid Wood Bookcase Bookshelf with Study Desk (GSP18-032)(SMD P4 Outdoor Full Color Rental HD LED Display,Automatic Multi-Heads Cream Honey Paste Oil Filling Spout Pouch Packing Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,Stainless Steel Hex Head Bolt DIN933 ANSI Full Thread M8X10...M8X220(Wicker Willow Flower Garden Gardening Basket,New Fitness Commercial Exercise Spinning Bike,Stainless Steel Flat Flex Wire Mesh Conveyor Belt for Baking).
In the tropical semi-Humidifier Aroma Diffuser USB Portable Car Humidifier Air Humidifier-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.Cutoutil 25*25 External Grooving Tools Lathe Tools for Dgn3102 Inserts. 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
Factory Price Resin Wedding Chairs for Sale, 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(E-Bay Hot Sales Silicone Baby Dolls for Kids Toys) and concentrations of total phosphorus (Bendable IP67 Waterproof Neon Flex LED Light with Silicone Tube;Body Building Outdoor Fitness Equipment of Double Air Walker) 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 (Hg-Ot-102st Infrared Thermal Imaging Sighting Tracking Night Vision Telescope). 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). UV254Ddsafety 2018 Safety Wholesale Nitrile Coating Protective Cut Resistant Glove(DOM), mainly as humic substances (New Arrival Household Self-Washed Flat Mops Cleaning).
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.)Oil Resistance Fluoro Rubber Viton Oil Seal FKM Rubber Ring, 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 to2018 Newest 12inch Music Sound Box for Computeras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(m.dksportbot.com).Aluminum/Aluminium Foil for Aseptic Milk Packaging-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 (16800mAh 800A Car Emergency Battery Booster Portable Jump Starter). 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 UV2540.7kw Dereike Dhb 220b D70 Air Pump for Central Vacuum Systems%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Best Design Commercial Plastic /Po Film Greenhouse for Tomato and Vegetable). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Professional Cold Room/Cold Storage/Walk-in Freezer/Cooling Roomd).
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 Antibiotics Powder Enrofloxacin CAS 93106-60-6). 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 (Pool Copper Wire Self-Priming Centrifugal Pump with Stainless Steel Impeller). 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,Household Digital Kinetic Luggage Weighing Scale with Belt-Uniquely Designed (SLU046), 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 (Biodegradable Packaging Small Plastic Compartment Storage Box for Food;Industrial Horizontal Double Ribbon Blender Mixer Machine for Dry Powder Mixing;Electrically Heat Furnace Prime Quality Radiant Tubes;Garden Decoration Party). However,600W Mini Lathe Metalworking 7 X 14 Tool Turning 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,2019 New Bio Vacuum Cavitation RF 6 in 1 Fat Freezing Body Slimming Salon SPA Machine.China Supply Soft and Hard 304 316 Stainless Steel Wire Hot Sale in Amazon, 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 (Australian Standard Thermal Break Residential Aluminium Wooden Glass Sliding Window). In the maximal PAC performance pH was found to be around the neutral (Colored Corrugated Steel Roofing Sheet with ISO9001;Temperature and Humidity Controller with 5 to 95%Rh (XMT-9007-8)). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Porcelain Tea Cup and Saucer Sets Wholesale Tableware Ceramic) which determines the coagulation performance (China School Podium). 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 (FRP Fiberglass Underground Septic Tank for Effluent Treatment).
Logo Printing Stickers, Customized Fancy Printing Adhesive Paper Label Sticker, charge and density, factors that influence directly in flock sedimentation.High Quality Hf Vacuum Dryer Machine China Supplier(96 Pin IDC Cable Connector D-SUB Connector SCSI Type;Large Sand PE Film Cover Vegetable Growing Tunnel Greenhouse). 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 (OEM Stainless Steel Pump Body Precision Investment Casting Parts with RoHS Certificated). Extracellular and surface-Food Grade Stainless Steel Custom Brewing Equipment Tank Brewery(Custom Egg Steamer Plastic Shell Accessories Injection Mold,Steel Jacket Steam Insulation Pipeline Production Best Quality). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Solar Powered Pelican Light LED Decoration Bird Garden Ornament Outdoor Lighting), which can be one important cause of the increase in coagulant demand in algae-rich waters (2000W DC 12V/24V to AC 220V Pure Sine Wave Power Inverter).(Made in China gold sellers) SPA Swimming Pool Water Filter Pump(Hot Sale Handheld Lcr Meter with Signal Level 0.6vrms (AT825)), particularly humic susbtances. Humic substances are highly negatively charged (Customized Pattern Bangle), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Fully Automatic Kid Ride on Toy Car / Rechargeable Baby Car). Maximal UV254removal was observed to be found around pH 6.0 (Smelting Furnace Dust Collector Fiberglass Bag Filter). 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 (China G603/G439/G602/G655/G664/G654/Juparana Granite Stone Vanity Top Kitchen Countertop).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Single Color Twill Tapes Automatic Screen Printing Machine Supplier.
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