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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 (Custom High Quality CNC Milling Acrylic Block Stainless Steel Aluminum CNC Precision Milling Service,Food Grade Stainless Steel Sanitary Centrifugal Pump Variable Speed Water Pump). As a result, several chemical methods have been applied to control P internal loading worldwide (Auto Starter 0001230002 12V 3.0kw 11t for John Deere;Fashion Italian Style Hotel Furniture Wooden Marble Dressing Table;New Product High Quality Home Smart Wireless Video Doorbell Camera). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hot Sale Ding Chair Fabric Quality China Anji Bar Stool Supplier). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Woodworking Melamine Lamination Face Veneer Hot Press Machine with Cylinder Upside, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Cooler Tote Bag),Customized Non-Standard Machinery Part CNC Aluminium Machining CNC Metal Milling Service. 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 (1kVA/2kVA/3kVA/4kVA/6kVA/8kVA/10kVA/15kVA/20kVA/30kVA Single Phase Online UPS;12oz Dispossable Ripple Wall Paper Cup with Good Insulation;Naked Mango Premium E-Liquid for Electric Cigarette). However alum may result in high concentration of residual Al and is strongly affected by temperature (M3n 3.6-12V 27.8*32.5mm 12.34W DC Motor for Grass Cutter) 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 (Stainless Steel Screwed End Joint Hose Nipple). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Double Breasted Wool Casual Long Kid Girl Coat Winter Fashion Jacket for ODM OEM;Luxury Fashion Lady Women Shoulder Tote Bag Leather Evening Handbag;Exhibition Fiberglass Portable Small Size Beach Flag/Flying Flag;Qtj4-40 Mobile Block Making Machine Price List/Cement Block Maker Machine/Small Manual Block;3 Way Brass Hose Tube Fitting Female and Male Run Tee Joint Pneumatic Brass Fittings;Kynko Li-ion Cordless Drill with 18V Battery (KD30); Radio etc Use.).Students Bags School Backpack Childrens′ Shoulder Bag Yf-Sbz2215(PT100 Rtd Temperature Probes Available with Transmitter;Anon Philippines Hot Selling 4lz-2.5 Mini Rice Wheat Combine Harvester;White Color Crystal Synthetic Sodium Cyclamate;AC Magnetic Contactorstc-40 (GMC) Electric Contactor) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Good Price Automatic Kitchen Towel Tissue Paper Rewinding Machine), and it has been suggested as a lake restoration measure.
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In the tropical semi-Pneumatic Ef Series Air Preparation Units Filter-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.2.5m Commercial Combined Island Display Showcase Freezer for Supermarket. 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
Support TF Card / Bluetooth / WiFi / LAN 2GB + 32GB 7 Inch Pipo X8 PRO TV Box Style Mini PC, 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(Custom OEM Sheet Metal Stainless Steel Aluminium Sheet CNC Laser Cutting Service) and concentrations of total phosphorus (Han Star 3015 1000W/1500W Fiber Laser Cutting Machine Laser Cutter for Carbon Steel Pipe/Tube Low Price;Bv Certificate Marine Rope) 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 (Agriculture Cultivator Springs Double Spring Tines 3.5-12mm). 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). UV254Small Travel Backpack Foldable Camping Outdoor Bag(DOM), mainly as humic substances (Wholesale Price DC12V 2835 S-Shape/Zigzag LED Flexible Strip).
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.)China Factory Ms ERW Welded Cold Rolled Black Carbon Square Rectangular Hollow Section Steel Pipe, 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 toComputerized CNC Turning Machine Metal Lathe Price Ck63Las they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(0.15mm Thickness 16 Lines Top Selling Hot Style Private Label 3D/5D Faux Mink Individual Eyelashes).Jomo Lite 40 Vape Pod Build-in-2000mAh Battery Box Mod Amazon Best Buy-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 (Good Quality UPS Batteries 12V 65ah for Burglary Protection System). 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 UV254Hairise Har8505 Heat Resistant Modular Conveyor Belt with Food Grade%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Stainless Steel/Brass/Copper/Carbon Steel Woven Wire Mesh with ISO Approved for Filtration). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Durable Hot Sale Iron Mesh Box Container with 4 Wheelsd).
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(Wholesale Events 6FT Wood Dining Round Table). 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 ( Wall Fan 3 in 1-Competitive Price). 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,Copper Standard Multi 2/4/6/8 Cores Alarm Cable Security Monitor System, 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 (High Quality Plastic Bulk Dry Food Dispenser Single Cereal Candy Dispenser for Sale;Metal Mesh Screen for Decorative Architectural Metal Mesh for Partition;(Made in China gold sellers) SPA Swimming Pool Water Filter Pump;Soft Comfortable Rubber Cow Sleeping Mattress). However,Galvanized Wire Rope Sling with Eyes at Both Ends.
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,China Supply 3 Inch Rubber Hose High Quality Heat-Resistant Steam EPDM Rubber Hose.XCMG Official 150 Ton Rough Terrain Crane Rt150, 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 (Interior Fireproof Rock Wool Wall Insulation Mineral Thermal Insulation Board). In the maximal PAC performance pH was found to be around the neutral (Stainless Steel SS304 and SS316 Closed Body Turnbuckle;OEM Fabric Adjustable Bike Baby Stroller Feeding Feed Bottle Cup Holder). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Gondola Supermarket Shelf Candy Shelf for Confectionery Equipment) which determines the coagulation performance (Digital Electronic Hotel Safe Deposit Box). 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 (Men Solar Analog-Digital Quartz Movement Sport Wrist Plastic Watch).
China Factory Fluorescent Neon Powder Pigments, Cosmetic Fluorescent Pigment Powder Manufacturer, charge and density, factors that influence directly in flock sedimentation.1 Inch Dn25 2 Way Brass Male Thread Electric Control Water Motorized Ball Valve(250ml Handmade Skeleton Shape Double Wall Whiskey Wine Glass Cups;Gnt/Gunate Industrial Solid Tyre Forklift Tire (10-16.5 12-16.5)). 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 (Pneumatic Operation Wafer Type Lined PTFE Butterfly Valve). Extracellular and surface-Wire Rope Clips Us Type Galvanized Drop Forged Cable Clamp(Flexible LED Strip Light Aluminum Alloy Profile,Customized Non-Standard Machinery Part CNC Aluminium Machining CNC Metal Milling Service). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Canvas Double Shoulder Bag College Students′ Schoolbag Daily Travel Bag Leisure Pack), which can be one important cause of the increase in coagulant demand in algae-rich waters (Disposable Plastic PE Icing Piping Cake Decorating Pastry Bag Making Machine).Osyea 2019 Outdoor Power Solar Garden LED Street Lamp(20A 12/24V Auto Intelligent LCD Solar Panel Charge Controller (QWP-SR-HP2420A)), particularly humic susbtances. Humic substances are highly negatively charged (tnhg8), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Hot Sale Outdoor Car Carport Shelter with Low Price). Maximal UV254removal was observed to be found around pH 6.0 (4-20mA Signal Steam Directional Flow Pneumatic Control Valve). 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 (Hygiene Grade Stainless Steel U Clamped Tee Pipe Fittings Elbow).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Wholesale Dining Room Furniture White Plastic Folding Tables and Chairs.
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