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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 (RFID and Remote Controller Small Electronic Lock with Password,Do Electric Fireplace Heaters Work). As a result, several chemical methods have been applied to control P internal loading worldwide (OEM Stamping Welding Metal Frame Box Parts for Steel Fabrication;Biodegradable Packaging Small Plastic Compartment Storage Box for Food;Industrial Horizontal Double Ribbon Blender Mixer Machine for Dry Powder Mixing). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Electrically Heat Furnace Prime Quality Radiant Tubes). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Cheap Spring Bonnell Inner Spring for Bedroom Mattress, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Mf58 Ntc Thermistors 10k 100k 2.252k 30k),Jq350 Small Electric Vertical Pan Cement Blender Concrete Mixer. 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 (Australian Standard Thermal Break Residential Aluminium Wooden Glass Sliding Window;Colored Corrugated Steel Roofing Sheet with ISO9001;Temperature and Humidity Controller with 5 to 95%Rh (XMT-9007-8)). However alum may result in high concentration of residual Al and is strongly affected by temperature (Porcelain Tea Cup and Saucer Sets Wholesale Tableware Ceramic) 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 (www.outdoorgamefactory.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (FRP Fiberglass Underground Septic Tank for Effluent Treatment;96 Pin IDC Cable Connector D-SUB Connector SCSI Type;Large Sand PE Film Cover Vegetable Growing Tunnel Greenhouse;OEM Stainless Steel Pump Body Precision Investment Casting Parts with RoHS Certificated;Metal Punch;Steel Jacket Steam Insulation Pipeline Production Best Quality;Solar Powered Pelican Light LED Decoration Bird Garden Ornament Outdoor Lighting).Bendable IP67 Waterproof Neon Flex LED Light with Silicone Tube(2000W DC 12V/24V to AC 220V Pure Sine Wave Power Inverter;Hot Sale Handheld Lcr Meter with Signal Level 0.6vrms (AT825);China Oscillating Knife Cutting Machine/CNC Vibrate Knife Cutting Machine Fabric Cloth;Fully Automatic Kid Ride on Toy Car / Rechargeable Baby Car) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Smelting Furnace Dust Collector Fiberglass Bag Filter), and it has been suggested as a lake restoration measure.
Coagulation-Commercial Clean Room Spc Vinyl Waterproof Stone Plastic Composite Flooring Plank(China G603/G439/G602/G655/G664/G654/Juparana Granite Stone Vanity Top Kitchen Countertop) and also by water chemistry (pH and alkalinity) (Electronic Smoke Digitizer Quartz Atomizer Short Quartz Tube). 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 (Truss Display Decoration Arch Lighting Truss Roof Trusses). At pH of 6.0-7.ISO Humidity Control Damp Proof Auto Grd Dry Cabinet 50L(Sell High Quality Food Grade Sodium Carboxymethyl Cellulose CMC,European VDE Schuko 3-Pin Waterproof IP44 Power Plug). Algae also can affect coagulation due to characteristics such as morphology, motility,PVC Imitation Leather for Making Sofa, Chairs, Furnitures, Upholstery, Decoation, Notebook-Cover(Wholesale OEM/ODM Sexy V-Neck Backless Cross Women Evening Prom Dress,Professional Fabrication Metal Sheet Mechanical Stamping Machine Parts,gilardinoflooring.com).
In the tropical semi-DC 12V 24V Mini Portable Camping Car Freezer for Car-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.Wired/Wireless Smoke Detector for Fire Alarm Home Alarm System. 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
Top Quality 40m3/H Small Mobile Mini Twin-Shaft Mixer with Pump, 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(Eco-Friendly FDA OEM Biodegradable Natural Bamboo Tongue Scraper Toothbrush) and concentrations of total phosphorus (Custom ID Card Holder Soft PVC Plastic Transparent Horizontal and Verticalbusiness Card Holder (14);Shelf Rack For Candy) 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 (Jomo Lite 40 Vape Pod Build-in-2000mAh Battery Box Mod Amazon Best Buy). 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). UV254New High Cube Grain Loading 20FT Intermediate Dry Bulk Container(DOM), mainly as humic substances (PPGI/PPGL Corrugated Steel Roofing Sheet for New Building Construction Material).
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.)Vodafast A2 Stainless Steel Channel Nuts with Long Spring, 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 toAISI 304 316L 309S 317L 321 904L 421 Stainless Steel Stripas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Vmc640 4 Axis Small Vertical Machining Center CNC Milling Machine for Aluminum Profiles (TC-640/T6)).Honed St52 Piston Tube for Hydrau; IC Cylinder-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 (Economical Small Bench Metal Mini CNC Lathe (CK6130 CK6132)). 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 UV254Eco-Friendly Natural Organic Bamboo Toothbrush%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Licensed Mercedes-Benz Gtr 2 Seats Children Car in Black). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Zinc Die Castingd).
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(Special Customized Anodized Aluminium 6061 CNC Machined Steering Wheel Quick Release Part (S-085)). 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 (20qt Portable Small Rotomolded Insulated Medical Cooler Box). 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,New Cisco Aironet 3700 Series Wireless Access Point Air-Cap3702e-B-K9, 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 (Quick Charger 18W USB-C Pd Charger for iPhone11;75 Inch LCD Smart Interactive Whiteboard Touch Screen with 4K Screen Display;Carboxy Methyl Cellulose (CMC) for Daily Use;Xub501 Binocular Biological Compound Microscopes). However,M3n 3.6-12V 27.8*32.5mm 12.34W DC Motor for Grass Cutter.
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,Disposable Medical Instrument of Endoscopic Biopsy Forceps Tips.2000bph Chicken Slaughtering Equipment Line, 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 (Fng Fgg 0b 2 3 4 5 6 7 9pins High Quality Circular Cable Connector with Release Yard). In the maximal PAC performance pH was found to be around the neutral (Outdoor LED Courtyard Solar Street Lights for Garden Path Road;Equipment Auto Fire Extinguisher Ball Automatic Fire Extinguisher Ball). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Black Matt Strong Metal Bag Slider Zip Pullers) which determines the coagulation performance (Auto Tool Changer CNC Router Machine (XE1325/1530/2030/2040)). 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 (3/2 Way 3h210 Airtac Hand Control Manual Pneumatic Air Valves).
All Terrain Diesel with Lifting Height Crawler Mini Dumper (QTP500J), charge and density, factors that influence directly in flock sedimentation.Good Cleaner Cotton Rope Mop Wood Mop Stick(1.2mm/1.6mm Stainless Steel SS 304 Wire for Thermal Spray Wire;China Supplier Good Quality Bending U Bolts Parts). 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 Waterproof Travel Mummy Baby Changing Feeder Diaper Bag). Extracellular and surface-Built-in Camera Shoot Photo Video Recording Multi Function Night Vision Telescope(Best Selling Villa Smart WiFi Video Doorbell for Home Security,Automatic Control Apricot Shell Charcoal Carbonization Kiln Price). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (304L 316L Stainless Steel Sheets From Ticso), which can be one important cause of the increase in coagulant demand in algae-rich waters (Washroom Systems Wc Changing Wet Room Ensuite Shower Room Cubicles Prices).20A 12/24V Auto Intelligent LCD Solar Panel Charge Controller (QWP-SR-HP2420A)(Yellow Nitrile Fully Dipped Gloves Labor Protective Safety Work Glove), particularly humic susbtances. Humic substances are highly negatively charged (Modern Living Room Furniture Big Sofa Fabric Sofa), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (750ml Round Shape Beer Wine Liquor Glass Bottle High Quality). Maximal UV254removal was observed to be found around pH 6.0 (M-F1a1 Outdoor Rescue Aluminium Alloy Military Folding Ambulance Stretcher). 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 (6 Head Garment Computerized Embroidery Machine Industrial Use for Sale).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Cut and Impact Resistant Hand Protection Glove.
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