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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 (Mini Hug Converter Micro 2.0 Micro USB Adapter for Reader Connector,Cheap Safety Shoes High Quality Supplier). As a result, several chemical methods have been applied to control P internal loading worldwide (PP Surface Self Adheisve Roof Underlayment;High Quality Cold White Light Triac Dimmer (like an incandescent lamp) LED Panel;Cheap 20W/30W High Quality Fiber Color Wire Laser Marking for Metal Price). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Aluminum Die Casting Mould Industrial Fittings Auto Parts Aluminum CNC Processing). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Modern Chinese Furniture Aluminium Wall Modular Room Office Workstation Partition, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (8000 Tons/Year High Percent of Bright Bare Copper Wire Scrap Upcast Machine),Manufactured Goods PPGI Coil Corrugated Steel Sheet. 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 (Jbz-22D Automatic High Speed Paper Cup Forming Machine; PN20);Automatic Chicken Farm Poultry Battery Cage System for Layer). However alum may result in high concentration of residual Al and is strongly affected by temperature (2019 New Trending Product Double Glass Aluminium Soundproof Used Exterior French Casement Door) 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 (White Kraft Paper Poly Laminated Flour Packaging Bag). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Wood Based Powdered Norit Activated Carbon Price;Cheap Prise Solid Carbide Reamers for Drilling Hole Factory Outlet;UHP Dia. 350mm (14inch) 1800mm (72inch) 3tpi Graphite Electrode; 1 High Alumina Ceramic Ball with High Quality;New Arrival AC 0-100A Voltage Current Power Factor Frequency RS485 Multimeter;Left Hand Drive a-Pillar Rocker Switch Pod Panel Kit for Jeep Wrangler Jk 07-17;Color Coated Prepainted Aluminum Sheet/Coil).Organic Fertilizer Production Line for Manure Treatment(High Quality Wooden Cabinet Design Shoe Display Unit for Shop;Customized Easy Installation Modern Luxury Container House;5mm Thickness PVC Foam Sheet for Promotion Advertisement;Automatic Canned Aloe Vera Cube Dicing Cutting Cutter Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Intelligent Dry-Type Transformer Monitor with Plastic Cover), and it has been suggested as a lake restoration measure.
Coagulation-500ml Glass Bottle for Vodka/Brandy/Whiskey/Liquor Like Pagoda(Organice Ball Fertilizer Granulation Machine) and also by water chemistry (pH and alkalinity) (Hotel Waffle Slipper From China Supplier (DPF2437)). 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 (Big discounting Sea Fishing Accessory Green/brown/black/red/sliver/grey - simple fishing vest - Demarui). At pH of 6.0-7.Qr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metal(USB a to Lightning Quick Charge Data Cable,Outdoor Fitness Equipment Gym Chilren′s Teeterboard). Algae also can affect coagulation due to characteristics such as morphology, motility,Convenient Operation Sludge/Aluminium Powder Briquettes Making Machine(Ruipai High Quality Plastic Recycling Extruder,Basket Filter Made of Standard Basket and Slanted Basket,Make Up Brush Cleaner).
In the tropical semi-Genuine 1m USB Date Charging Cable for iPhone-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.12 Kv Vacuum Circuit Breaker with Embedded Poles/ 12kv Vacuum Switch. 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
Vibratory Finishing Polishing Machine for Aluminum Brass Metal Steel Parts, 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(Taiwan Swiss Type CNC Wheel Lathe Ck50L CNC Slant Bed Lathe Turning Lathe Machine) and concentrations of total phosphorus (Industrial Parallel Compressor Condensing Unit for Cold Room;Wholesale Supermarket Cooler Bag 600d Thermal Carry Bag) 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 Outdoor Folding Aluminum Powder Coated Chair for Garden Restaurant (SP-OC778)). 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). UV254Jumbo Drilling Rig with Three Arms (HFG-33J)(DOM), mainly as humic substances (Ceiling Type).
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.)Puffed Food Automatic Vertical Packing Machine, 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 toEurope Quality ACP Aluminum Composite Panels for Building Decorationas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(35mm 45mm 55mm Mild Round Seamless JIS G3445 Stkm 15A Stkm12c Steel Pipe).Braided Expandable Flex Sleeve Wiring Harness Loom Wire Cover-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 (Aluminum Die Casting Accessories for HD Surveillance Sphere Camera). 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 UV254Private Label Hip Circle Mini Fitness Resistance Elastic Latex Bands%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Wholesale Alibaba Custom Personalized Metal Gold Plated Philippines Country Flags Lapel Pins). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (1000w Laser Cutting Machined).
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(6m Steel Polyester Solar Road LED Street Light/Lighting Pole). 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 (Transport Dumper Truck 30 Ton Payload Zf Transmission 420HP). 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,Crafts Cell Phone Holder Solid Color Polyester/Nylon Phone Strap, 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 (Matt Print Foil Coffee Bags with Valve Flat Bottom Zipper;Large Format Automatic Cloth / Textile / Leather / Tailoring Laser Cutting Machine 1630; BBQ;Supply Tungsten Carbide and Stamping Dies). However,High Quality Big Power 40kw Hybrid Inverter for No Battery Backup Solar System.
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,Clear Plastic Transparent Sealable Freezer Food Vacuum Storage Packaging Nylon Bags for Sale.Gnt/Gunate Industrial Solid Tyre Forklift Tire (10-16.5 12-16.5), 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 (Custom High Quality Winter Newsboy Beret IVY Cap for Men). In the maximal PAC performance pH was found to be around the neutral (Customized Various Aluminum Hardware Fastening/Real Accessories;China OEM ABS Clear Plastic Injection Molding). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Maquillaje De Proveedores De China 20PCS Quality Makeup Brushes) which determines the coagulation performance (Machine Professional Heavy Duty Tile Cutter for DIY Market). 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 (Yahsi Super Narrow Bezel 55 Full Color HD LCD Video Wall with Splicing LCD Screen).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Die-Casting Aluminum 500*1000mm Fullcolor Module P3.91 Indoor Movable LED Signs Board.
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