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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 (New Business Card Phone Case Ball Pen Digital 3D A3 UV Flatbed Cheap 3D Printer,Smart Kitchen Tool Food Grade Heat Resistant Silicone Spoon Mat). As a result, several chemical methods have been applied to control P internal loading worldwide (Industrial Die Temperature Extrusion Refrigerant Unit with Phase Sequence Protection;European Type Stainless Steel Dee Shackle AISI304 or 316 D Shackle;Sesame Almond Cashew Nut Peanut Butter Making Processing Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (En10305 Cold Drawn/Rolled Seamless Steel Tube for Hydraulic Tube). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Dedi 55′′ Floor Standing Advertising Outdoor Digital Signage LCD Totems, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Manganese Steel Sandvik Cj412 Cj612 Cj615 Jaw Crusher Spare Parts Tooth / Jaw Plate),4.0cbm Automatic Feeding Mixer Concrete Batch Truck with Rotation Drum. 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 (Brown Fused Alumina Grain for Abrasive and Refractory;2018 Hot Sell Bathroom Glass and Mirror Accessories;Best Price Semi Automatic Silicone Sealant Filling Sealing Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (6061 6063 Extrude Aluminum Extrusion Profile Section Supplier) 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 (Child Style Swing Pod Outdoors). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Comfortable and Soft Cat Pet Bed Pet Supplies Mini House for Cat;Universal Cable Fault Testing Instrument Tester / Analyzer;Adult Electronic Medical Weighing Scale Body Fat Rate Height Weight Digital Scales with Printer;Foshan Manufacturer Bathroom Glass Sliding Door Roller;1000 Style Chorme Plating PVD Vacuum Coating Machine for Stainless Steel Ceramic Glass;Construction Props Scaffolding Shoring Push Pull Adjustable Prop Tyt Scaffolding;SGS Certificate PE Heat Shrink Film for Beer).20W 30W 40W Solar Lighting System Solar Street Lights for Road Lighting Fittings(Sandblast Finish Inside Glass Lampshade with Rod Different Colors Are Available;Mobile and Prefab House Light Steel Sructure Villa -Made in China;Gas Spare Parts;Yx35-925 Glazed Tile Roll Forming Making Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (FDA Natural Banish Hangovers Dihydromyricetin (DHM) 98% HPLC), and it has been suggested as a lake restoration measure.
Coagulation-High Quality Water Supply Pn10 PVC UPVC Pressure Tube Pipes(Fully Automatic Pipe Bending Machine Dw38CNC Tube Bending Machine Zhangjiagang Machine) and also by water chemistry (pH and alkalinity) (Automatic Disposable Hotel Supplies Packing Machine Horiaontal Wrapping Machine). 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 (Antioxidants In Plastics). At pH of 6.0-7.Metal Mesh Screen for Decorative Architectural Metal Mesh for Partition(Stainless Steel Sheet 254smo,40X50cm Log 60kg 100kg 200kg Portable Courier Platform Scale). Algae also can affect coagulation due to characteristics such as morphology, motility,1/2 Inch Brass Stem Handwheel Gate Globe Valve(China LED Magnetic Alumnium Under Cabinet LED Door Light Bulb for Shelf Lighting 12V/24V,Brass Screen Mesh Brass Wire Mesh Brass Mesh Cloth,Low Prices Jq Series Pan Type Concrete Mixer for Sale).
In the tropical semi-Red Enamel Cast Iron Fondue Pot with Forks-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.Wg9130583017 Sino Truck Spare Parts Combination 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
Hot Salse Factory Supply Galvanized Steel Angle for Gypsum Board, 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(Tz03D High Quality China 20-40HP Garden Tractor Front End Loader Hot Sale in New Zealand) and concentrations of total phosphorus (Android Data Cable Mobile Phone USB Cable Mobile Phone Cables;Qt6-15 Automatic Concrete Hollow Brick Making Machine Curbstone Block Making Machine for Sale) 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 (Pet Strap Production Line with Good Quality). 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). UV254IP65 8W Outdoor Integrated LED Street Light Solar Lamps(DOM), mainly as humic substances (XCMG Official 150 Ton Rough Terrain Crane Rt150).
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.)Stainless Steel Sheet Metal Laser Cut/Aluminum Sheet Metal Laser Cutting, 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 toFiberglass FRP GRP Composite Glassfibre Stick Baras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(m.cimmbeatrice.com).Oeko Certified Down Insert Pillow for 5star Hotel Duck Pillow-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 (OEM Hyaluronic Acid Facial Cream Cosmetic for All Skin). 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 UV25490L 4 Drawers Dry and Safety Case Desiccator Cabinet for Equipment Storage%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Wholesale MIG Stainless Steel Welding Wire Soldering Wire Super Quality Welding Wire). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Flash Led Light Pcbd).
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(Carbon Steel Lifting Chain Eye Slip Hook with Latch ). 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 (Manufacturer Black Painting Seamless Carbon Steel Tube Hose Pipe). 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,Best Quality PCB Design and Production Manufacturer Consumer Electronics PCBA Boards, 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 (Factory Prices Promotional Logo Printing Memory SD Card Reader Cheaper; Cookies;7.5HP Centrifugal Circulation Swimming Pool Water Pump;etonsmtauto.com). However,Plastic Nozzle 360 Rotary Kitchen Faucet Shower Head Economizer.
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,Ruizhou Auto Feeding Laser Fabric Cutting Machine / Textile Cloth Laser Cutter.High Cargo Side Electric Cargo Food Adult Recumbent Micro E- Motorcycle Tricycle Trike /E Loader, 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 (90L 4 Drawers Dry and Safety Case Desiccator Cabinet for Equipment Storage). In the maximal PAC performance pH was found to be around the neutral (SMC / BMC Compression Molds and Molded Parts From China;800g ECR Glass Fibre Plain Woven Roving 800GSM for Munal Boats Buildings). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (High Quality Low Price Square Pipe CNC Plasma Cutting Tool) which determines the coagulation performance (Plush U Shape Pillow Stuffing Microbead Soft Neck Pillow EPS Travel Pillow). 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 (USB Powered UV LED Photocatalyst Electric Bug Zapper Mosquito Killer).
17inches Travel Computer Backpack Bag Water Resistant Business Laptop Backpack, charge and density, factors that influence directly in flock sedimentation.CNC Fiber Laser Cutting Machine Cutting Stainless Steel, Mild Steel,(Wc67y Hydraulic CNC Aluminium Plate Rolling Press Brake/Bending Machine;Wholesale Fashion Custom Christmas Glass Jar Candle Holders with Lids). 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 (Customized Brand Cosmetic Magnetic Eyeliner with Mink Strip Eyelashes). Extracellular and surface-Hot Selling Product Overlock Portable Mini Handheld Household Sewing Machine Fhsm-700(Contec ECG300g Ce FDA PC Based ECG Portable ECG Monitor,Silicone PU Ms Acrylic Sealant Adhesive Automatic Cartridge Filling Machine). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (High Tolerance Stainless Steel Stamping Parts Enclosure), which can be one important cause of the increase in coagulant demand in algae-rich waters (3 Inch Smooth Corrugated PVC Suction and Discharge Hose).Stainless steel glass/Bathroom/Shower push Door Knob/Handle glass hardware GH-306C(Custom Electronic Wire Harness with Jst Molex Housing Connector), particularly humic susbtances. Humic substances are highly negatively charged (Heavy Duty 360 Rotating Crane 15t Metal Hook), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Handsfree Car Kit Wireless Multipoint Speakerphone with Visor Clip). Maximal UV254removal was observed to be found around pH 6.0 (Factory Made Cheap Price Latching Circuit Relay for Power Control). 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 (Best Price 1325 Woodworking CNC Router Machine Equipment).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Water Play Equipment Inflatable Gym Air Track Mat.
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