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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 (Theater Hall VIP Writing Tablet and Desk Commercial Seat Press Cinema Chair,peas-pa). As a result, several chemical methods have been applied to control P internal loading worldwide (Greatly Improved Brown Coal Briquette Machine With Low Energy Consumption;RoHS Stainless Steel Passivated Ground Pin 14.6X1.5mm;Outer Side Mirror Left and Right Rearview Mirror for Skoda). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Monofilament Fibrillated Twist Wave Polypropylene Fiber PP Fiber for Concrete). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Stainless Steel Black Matt Kitchen Faucet, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Washi Masking Tape Decorative Tape Collection for Scrapbooking),Ceramic Components Applied in Machinery Industry. 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 (NdFeB Magnetic Strong Sintered N45 Rare Earth Permanent Neodymium Magnets for Motor;Constant Temperature Hot Water Machine Swimming Pool Heat Pump;Decorative Marble Pattern Coated Aluminum Sheet/Coil for Building Material). However alum may result in high concentration of residual Al and is strongly affected by temperature (Shoebox Canopy Lamp 60W LED Light Evergy Saving 2835 Chips Corn Bulb) 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 (Magnetic Stripe Card Cmyk Offset Printing Card). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (LDPE Plastic Garbage Bags for Construction Wastes;15 Years Factory OEM Plastic Injection Molding Kid Learning Machine Parts;Fast Building Luxury Mobile Modular Container House Material Living Container Buildings;Ifm Induction Furnace Manipulator Pushing Scrap Steel Reducing Melting Time;Industrial Paper Production Making Machine Ss Cylinder Mould;Fenbendazole CAS43210-67-9 Pesticide Vetetinaries Good Manufacturing Practice;Adhesive Cut Table Heat Press PU Flex Vinyl/Film for T-Shirt).Rock Wool Color Steel Sandwich Panels for The Construction of Cleanroom(New Model Polished Porcelain Glazed Marble Ceramic Floor Tiles for Project;Wholesale Sport Wear Mens Gym Running Polyester T Shirt;Full Automatic High-Frequency Carbon Steel Tube Mill for Round/Square/Rectangular Pipe;Compatible Physio Control 11996-000033 NIBP Hose) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Plastic Polypropylene Honeycomb Core Is The Ideal Component for Any Lightweight Assembly), and it has been suggested as a lake restoration measure.
Coagulation-Wall Mounted Bathroom Tissue Holder Toilet Paper Towel Roll Holder(Custom PVC Shrink Capsules for Liquid Bottle) and also by water chemistry (pH and alkalinity) (Newest Double Color WPC 3D Wood Grain Plastic Composite Flooring). 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 (Social Auditing). At pH of 6.0-7.Ride on Concrete Power Trowel Machine with Suitable Seat(Three-Phase Electronic Multi-Function Watt-Hour Current Meter,Valve Wheel Adjustable Hydraulic Impact Torque Wrench). Algae also can affect coagulation due to characteristics such as morphology, motility,Concrete Grinding Plate for Abrasive Machines of Abrasive Disc(Fashion Double Striped Non-Slip Entrance Mat,Sofa Cushion Wholesale Customized Pillow Cover Home Decorative Throw Pillow,Essential Oil Diffuser Ultrasonic Humifier for Home Fragrance).
In the tropical semi-Duplex Parallel Connection Bag Filter for Filtering Drinking Mineral Water-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.China New Design TPU/PVC Layflat Flexible 6 Light Duty Suction Hose. 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
2018 Chinese Single Person Best Plastic Fishing Kayak Sit on Top, 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(TPR Vibration Protection Cut Resistant Safety Work Glove for Industrial Purpose Use) and concentrations of total phosphorus (Wholesale Comfortable Men′s Winter Leather Snow Boots;Sublimation Coating Powder Chemicals for Heat Tansfer Paper) 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 (High Quality Free Sample Woven Label for Garment Accessories). 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). UV254Laminated Glass Auto Clave with TPC/PLC System (SN-BGF3060)(DOM), mainly as humic substances (Rls9 Zz-2RS Ls11 Lj-1-1/8 Cixi Inchi Wheel Roller Ball Bearing).
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.)Modern Design Oval LED Lighted Beveled Edge Wall Fogless Bathroom Mirror, 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 toMicron Circular Stainless Steel Filter Discas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Outdoor Light 5W 7W 15W Solar Garden Lawn Lamp).7 Inch Wired Color Villa Video Door Phone with Coms Camera V7c-P1 Intercom System-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 (Agriculture Machinery Belt Banded Cogged V-Belt). 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 UV254Monofilament Fishing Tackle Green Nylon Fish Net%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Nonwoven PP Fabric Nonwoven Needle Punched Geotextile). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Executive Office Chair Racing Car Seat Computerd).
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(Sancore Nappa Leather Back Sticker Huawei Mate20/PRO Phone Case). 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 (Anti-Aging Dredger UHMWPE/HDPE Sand Mud Oil Dredge Floater Pipe Pipeline). 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,IP65 Waterproof Metal Distribution Box and Power Metal Box, 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 Efficiency Cleanroom Mini Pleat HEPA&ULPA Air Filter Media Pack;4.0cbm Automatic Feeding Mixer Concrete Batch Truck with Rotation Drum;Two Walls Stainless Steel Insulated Straw Cup Step Shape Metal Juice Cup with Straw;Side Table). However,Original Sinotruk HOWO Truck Spare Parts Trailer Control Valve Wg9000360525.
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,Metallic Paint Solid Aluminum Cladding Panels for Roof Covering/ Ceiling.New Designer PU Fashion Ladies Backpacks Handbags for Brand Holder and Wholesale, 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 (Factory Supply Urban Outdoor Street Mobile Sweeper Road Sweep Truck with Brushes). In the maximal PAC performance pH was found to be around the neutral (Spraying Rubber Asphalt Emulsion Waterproof Coating/Liquid Rubber Coating;Best Price Split Air Conditioner Stand/AC Stand). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Hotel Wall Mounted Infrared Battery Electric Liquid Automatic Soap Dispenser) which determines the coagulation performance (Composite Laid Scrims Mesh Fabric Manufacturers Cheap Price). 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 (Jumbo Drilling Rig with Three Arms (HFG-33J)).
Cal117 (TB117) Flame Retardant Fire Barrier Batting Felt, charge and density, factors that influence directly in flock sedimentation.Sri Lanka Metal Detector Handheld Metal Detector Explosive Detector(1.0 Ton Small Backhoe Crawler Mini Excavator Digger Machine for Sale;2017 Cheap China Pistol Safe Security Gun Safe Lock). 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 (Jq350 Small Electric Vertical Pan Cement Blender Concrete Mixer). Extracellular and surface-Yidek Electric Energy Supply Quality Intelligent Analysis Meter with Ce(Walking Beam Cooling Bed,Xaja Truck Light Wire Automotive Cable Trailer Wiring Harness). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (En71 Approved Baby Electric Toy Bike Kids Battery Motorcycle), which can be one important cause of the increase in coagulant demand in algae-rich waters (Siboasi Best Selling Badminton Shuttlecock Feeder Machine).Tractor Trailer Cable Truck 7 Core Spiral Coiled Electric Cable for Tractor & Trailer(ISO Linyi Apitong 28mm Marine Plywood Container Spare Parts), particularly humic susbtances. Humic substances are highly negatively charged (Best Price Aquarium Oxygenated Air Pump for Fish Pond), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles ( medical disposable clothes). Maximal UV254removal was observed to be found around pH 6.0 (Custom Fashion Apple Mobile Wooden Phone Case for iPhone (6/7/8/6s/8s Plus/Xs Max/Xr/Xs/8plus)). 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 (Pneumatic CNC Router 1325 Multi Heads Pneumatic Furniture Cutting Machine).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Easy to Use Mobile Filter Unit for Light to Medium Welding.
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