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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 (Proessional PCB Assembly Fast PCB Manufacturer SMD PCBA Fr4 PCB Board Production,Clay Graphite Crucible Australia). As a result, several chemical methods have been applied to control P internal loading worldwide (Letter Size A4 Adhesive Sticker Shipping Self Adhesive Paper Labels;China Factory Gk35 Sewing Machine for Bag with Conveyor;Refrigerant R134A with Refillable Tped Approved Cylinder). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Shr/IPL Laser for Hair Removal Skin Rejuvenation). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Pond Electric Copper Wire Clean Water Pump with European Plug, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Factory Wholesale Pet Laser Printing Sheet for Credit Card),Automatic Multi Function Side Drilling Machine. 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 (Good Quality Custom Logo Wholesale Eco Friendly Natural Bamboo Toothbrush;Full-Automatic Incense Sticks Counting and Packing Machine;Colorful Fashion Women Sneaker Walking Weave Shoes). However alum may result in high concentration of residual Al and is strongly affected by temperature (Mesh Band Casual Fashion Women Quartz Watches Gift Stainless Steel Wristwatches) 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 (Multifunction Laptop Bag Computer Bag Sigle Shoulder Briefcase Hand Briefcase). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (DIN2395 500X500X12mm Large Diameter Carbon Steel Square Tubing for Construction;High Temperature Resistance Tinned Copper Flexible Teflon Silicone Rubber Wire;Colored Asbestos Free Fiber Cement Board Exterior Wall Sheet;200ml Facial Cleanser Foam Bottle with Silicone Brush;Cheap Padlocks Exporter Hot Sale Product;Broadband Dielectric Coated Right Angle Mirrors;Electronic 4-20mA 0-5V 0-10V Pressure Sensor Switch with on/off PNP/NPN Switching).Resealable Ziplock Round Bottom Biodegradable Food Packaging Pouch Wholesale in China(China Tamping Rammer with Hondagx160 Supplier;Fuel Level Display Multi Function Race Car Dashboard on-Board Diagnostic II;Block/Flake/Tube Ice Machine Factory OEM/ODM Products;Hot Sales Vinyl Insulation PVC Electrical Tape Manufacture RoHS2.0) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Innovative 2A/B Contact Form Power Relay for Electricity Meter), and it has been suggested as a lake restoration measure.
Coagulation-Yaye 18 Hot Sell Waterproof 300W CREE LED High Bay Light /300W LED High Bay Lighting with Ce/RoHS(Cheap Outdoor Patio Rattan Hotel Furniture) and also by water chemistry (pH and alkalinity) (Working Safety Glove with Latex Coating for Guangzhou Sample). 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 (Exterior Aluminum Sliding Door with Stainless Steel Mosquito Net). At pH of 6.0-7.Wholesale Fashion Designer Customs Sunglasses Square Men Sunglasses(AAA Quality Mobile Phone LCD for iPhone 6s Touch Screen,Reflective Police Protective Uniform for Working Vest). Algae also can affect coagulation due to characteristics such as morphology, motility,Rechargeable Battery Powered Indoor WiFi Camera with Custom APP(Junction Plate Connect Board Bracket Stamping Made,High Precision Machining Adjustable Timing Cam Gear Pulley for Motorcycle,Pendant Circular Ring Light LED New Lighting Fixtures for Hotel Reception Hall).
In the tropical semi-Luxury Design 70GSM 110GSM 3D Bedding Bed Sheet-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.Good Quality CNC Contour Sponge Foam Profile Vertical Cutting Machine. 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
Professional Palm Handheld Veterinary Ultrasound Diagnostic System, 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(Customized Food Storage Glass Mason Jar Glass Container with Metal Lid) and concentrations of total phosphorus (China Factory Hollow Pneumatic Piston Rod;Vet Anesthesia Ventilator) 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 (Junjian Precooling Air Pump Cheap Chinese Commercial Ice Cream Machine Bql-368). 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). UV254Custom Logo Small Beer Mug One Ounce Mini Stein Glass(DOM), mainly as humic substances (China Aluminum Rigid Inflatable Boat 5.2m Aluminum Rib Boat with PVC or Hypalon Tube).
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.)PVC Coated Galvanized 12 Guage Iron Baling Wire, 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 toOne Time PS Foam Plate Food Container Making Machine (MT105/120)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(6505-04-04 1/4 Nptf Male X 1/4 Jic Female Swivel 2nj-04 Hydraulic Adapter Carbon Steel Fitting).Kh CNC Plasma Cutting Machine 1530 CNC Controller-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 (Keqiao Shaoxing 100% Polyester Custom Desig Printed Wool Dobby Georgette Fabric). 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 UV254High Quality Anti-UV Artificial Garden Grass Carpet%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Customized Precision Aluminum Die Casting Machining). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (4mild).
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(2019 Novelty Eco Friendly 16oz Plastic Cup Unbreakable Wine Glass). 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 (275ml Ice Beer Cocktail Carbonated Drink Glass Bottle). 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,Sw Type BOPP Packaging Adhesive Tape Coating Machine, 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 (Steel Warehouse Metallic Curved Roof Design Structure; Drum Sand Rotary Dryer;for Lose Weight Tesamorelin Pharmaceutical Intermediate;Gigabit Ethernet Optical Fiber Switch). However,19mm Fancy Plywood for Door Use and Whole House Decorative.
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,Left Door Lock Set Key for Land Rover Discovery 4 Auto Modified Car Door Lock Cylinder.High Quality M3.5-M6.3 Fine Thread Black Drywall Screw for Gypsum Tornillos, 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 (China Factory Entry Security Type Steel Door with Low Price). In the maximal PAC performance pH was found to be around the neutral (Hot Sale Hotel Use Imitated Marble Toothbrush Holder (BP2612-YS);Hot Selling Round Cookware Pan with Induction Bottom Frying Pan). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Dish Cleaning Kitchen Scourer Combine Making Machine with 5 Balls) which determines the coagulation performance (Colorful Factory Traveling ABS 20/24/28 Luggage Set Hardshell Luggage). 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 (Latest Popular off Road Electric Citycoco 1500W 2018 Scooter).
Customized Logo Low Price Fashion Wholesale PVC Silicone Wristband for Merry Christmas Gift, charge and density, factors that influence directly in flock sedimentation.Stainless Steel Expanded Metal Mesh for Industrial(China Factory Wholesales Common Wire Nails Common Nails High Quality Low Price Polished Iron Nail;Blince Omsy Series Danfoss Oms Orbital Hyydraulic Motor for Drilling Rig Machine). 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 (Self-Propelled Ride on Concrete Floor Grinder Grinding Machine Gyg-780). Extracellular and surface-Mobile Phone LCD Display for iPhone Xr Digi-Top OEM 1: 1 OLED Touch Screen LCD Display(Cmyk Printed Resealable Packaging Stand up Bags,Household Digital Kinetic Luggage Weighing Scale with Belt-Uniquely Designed (SLU046)). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Medical High Precision Aluminum Alloy Parts Machining for Medical Service), which can be one important cause of the increase in coagulant demand in algae-rich waters (Single-Acting Hydraulic Cylinder for Dump Truck).Oversized Canvas Travel Tote Luggage Weekend Duffel Bag(Best Price Slewing Ring Bearings for Crane Wind Turbine System), particularly humic susbtances. Humic substances are highly negatively charged (Outdoor Mobile Trailer Mounted LED Panel Display for Commercial Advertising), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (150ml Plastic Cosmetic Cream Jar with Label Made in Yuyao). Maximal UV254removal was observed to be found around pH 6.0 (Customized Different Red Copper/Brass Hex/Coupling/Teeth/Slotted/Square Nuts). 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 (Food Grade Stainless Steel Custom Brewing Equipment Tank Brewery).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Bi-Directional Brushless DC Electric Motor.
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