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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 (16800mAh 800A Car Emergency Battery Booster Portable Jump Starter,BNC Video Power HD Cable Security CCTV Camera DVR Record Extension). As a result, several chemical methods have been applied to control P internal loading worldwide (Best Design Commercial Plastic /Po Film Greenhouse for Tomato and Vegetable;Closed Cargo Box Garbage Truck/Rubbish Collector Diesel Engine Tricycle;High Quality Antibiotics Powder Enrofloxacin CAS 93106-60-6). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Pool Copper Wire Self-Priming Centrifugal Pump with Stainless Steel Impeller). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,7 Liters Vertical Type Commercial Butchery Manual Sausage Filler, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Zap Brand Laundry Washing Detergent Powder Packing 200g),E-Bay Hot Sales Silicone Baby Dolls for Kids Toys. 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 (RFID and Remote Controller Small Electronic Lock with Password;OEM Stamping Welding Metal Frame Box Parts for Steel Fabrication;Biodegradable Packaging Small Plastic Compartment Storage Box for Food). However alum may result in high concentration of residual Al and is strongly affected by temperature (Industrial Horizontal Double Ribbon Blender Mixer Machine for Dry Powder Mixing) 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 (Customized Metal Blank Promotion Gift Key Finder). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Electrically Heat Furnace Prime Quality Radiant Tubes;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);OEM Small Parts Processing CNC Aluminium Machining CNC Milling Machining;Porcelain Tea Cup and Saucer Sets Wholesale Tableware Ceramic;FRP Fiberglass Underground Septic Tank for Effluent Treatment).AAC Block Making Machine Line Supplier/AAC Block Machinery(96 Pin IDC Cable Connector D-SUB Connector SCSI Type;Large Sand PE Film Cover Vegetable Growing Tunnel Greenhouse;White Fireproof Pvc Panel;OEM Stainless Steel Pump Body Precision Investment Casting Parts with RoHS Certificated) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Steel Jacket Steam Insulation Pipeline Production Best Quality), and it has been suggested as a lake restoration measure.
Coagulation-Desktop Fiber Laser Marking Machine with Computer Price $3300(Solar Powered Pelican Light LED Decoration Bird Garden Ornament Outdoor Lighting) and also by water chemistry (pH and alkalinity) (2000W DC 12V/24V to AC 220V Pure Sine Wave Power Inverter). 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 (Cabina de espray de la pintura de los muebles de China). At pH of 6.0-7.Eco Recycled Kraft Paper Box for Salad and Lunch(Hot Sale Handheld Lcr Meter with Signal Level 0.6vrms (AT825),Fully Automatic Kid Ride on Toy Car / Rechargeable Baby Car). Algae also can affect coagulation due to characteristics such as morphology, motility,Heavy Duty Galvanized Stacking Steel Pallet Shelving with Posts(Smelting Furnace Dust Collector Fiberglass Bag Filter,China G603/G439/G602/G655/G664/G654/Juparana Granite Stone Vanity Top Kitchen Countertop,New High Quality 3D Brick Pattern PVC Wall Paper for Home Decoration).
In the tropical semi-Guangzhou High Quality Spare Parts 2 Years Warranty Fit for BMW and Mercedes Benz-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.Custom Design Stainless Steel Sheet Metal Fabrication Box Cover. 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
Digital Printing Pillow for Sofa with Metallic Printing, 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(European VDE Schuko 3-Pin Waterproof IP44 Power Plug) and concentrations of total phosphorus (Wholesale OEM/ODM Sexy V-Neck Backless Cross Women Evening Prom Dress;Relay 40a) 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 (Waterproof Straight Male Female Sensor Connector). 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). UV254Micron Circular Stainless Steel Filter Disc(DOM), mainly as humic substances (Eco-Friendly FDA OEM Biodegradable Natural Bamboo Tongue Scraper Toothbrush).
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.)Wholesale Portable Travel Bamboo Tooth Brush Holder, 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 toJomo Lite 40 Vape Pod Build-in-2000mAh Battery Box Mod Amazon Best Buyas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Cup Wire Wheels Brush Set & Reduced Wire Breakage and Longer Life).High Quality Folding Us Plug 5V 1A USB Travel Charger-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 (White Chemical Coating Powder for Fast Dry Sublimation Paper). 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 UV254Tubular Polyethylene Plastic Film Blowing Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Trenchless Directional Tricone Drill HDD Reamer). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Antirust Chicken Layer Cage Designsd).
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(Nyp Rotor Type Oil Pump High Viscosity Internal Gear). 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 (BPW Spring Mechanical Steel Oil Fuel Diesel Tank Semi Trailer for Sale). 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,LED Screen Facial Comedo Nose Blackhead Cleanser Zit Extractor Tool, 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 (OEM / ODM Steel Material Controllable Piston Gas Lift Pressure Adjustable Gas Spring for Bus Seat;Special Customized Anodized Aluminium 6061 CNC Machined Steering Wheel Quick Release Part (S-085);20qt Portable Small Rotomolded Insulated Medical Cooler Box;Popular Design Double Bridge Women Metal Sunglasses). However,Custom Dye Sublimation Printed Phone Lanyard ID Badge Holder with Logo Custom.
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,Auditorium Chairs for Public Furnitures, School Furnitures, School Chairs (R-6130).Chrome Steel Cam Follower CF4 for Machine Parts, 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 (Creative Stainless Steel Guitar Shape Patch Empty Platinum Bottle Opener). In the maximal PAC performance pH was found to be around the neutral (1020 Schedule 40 Black Ew Steel Pipe 2 Inch Black Iron Pipe;Quick Charger 18W USB-C Pd Charger for iPhone11). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (75 Inch LCD Smart Interactive Whiteboard Touch Screen with 4K Screen Display) which determines the coagulation performance (Full Body Massage Shiatsu Kneading Neck and Shoulder Massager). 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 (Carboxy Methyl Cellulose (CMC) for Daily Use).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Resealable Ziplock Round Bottom Biodegradable Food Packaging Pouch Wholesale in China.
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