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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 (JAC 4X2 3ton 5ton Refrigeration Truck Freezer Box Truck,Radio Broadcasting). As a result, several chemical methods have been applied to control P internal loading worldwide (OEM Stamping Parts Aluminum Profile Stamping for Child Safety Seats;Automatic Fresh Fruit Juice Bottle Natural Fruit Canning Machine;Aluminum Motor Housing Used in The Electromotor / Electric Motor Industry). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Quality Medical Disposable Pen Type Blood Collection Needle). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Environmental Protection Material PLA Sheet for Cup Lid Tray Forming, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Spiral Dough Mixer in Kitchen Equipment with 16kgs (MF-40L16)),New Product Automatic Powder Machine for Filling and Packing Spices. 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 (Multifunctional RF/40K Body Vacuum Roller Weight Loss Beauty Salon Cavitation Beauty Equipment;Full Automatically Wp Line Powder Jet Mill Micronizer in Agriculture Field;Professional Super-Automatic Tyre Changer Without Lever). However alum may result in high concentration of residual Al and is strongly affected by temperature (Plastic PE HDPE LLDPE LDPE Irrigation Water High Speed Pipe Extruder Making Machines) 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 (Trending Products Nose Strips Vacuum Suction Blackhead Remover Vacuum). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Power Transformer Voltage Transformer Pq2620 Series High Frequency Transformer;Exdiibt4 Explosion Proof Type 10kw Power Inverter Built in Low Frequency Transformer;Stainless Steel Sanitary Pipeline Three-Stage Emulsion Mixing Pump;American Double Hung Thermal Break Aluminum Window in China;Chip Wooden Block High Quality Supplier;Best Industrial Coal Fired Steam Boiler Manufacturer in China;7 Colorful 240 Degree Wide Lens Mini Speaker Smart WiFi Camera of Night Light Wc001y13).LED Video Wall PCBA&PCB and LED PCB Design, 15 Years LED PCB Circuit Board China Supplier(18X18 Asian Black Iron Square Tube/Black Square Steel Pipe Seamless;Luxury Modern Bathroom Furniture Sanitary Ware Solid Surface Basin;Aluminum Anodized Profile/ Tubing for Solar Rack 6005 T5;Monofilament Fishing Tackle Green Nylon Fish Net) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Used Fashion Summer Children′s Dress Unsorted), and it has been suggested as a lake restoration measure.
Coagulation-Mini Hug Converter Micro 2.0 Micro USB Adapter for Reader Connector(Longboard or Skateboard Ball Bearings 608zz 608-2RS) and also by water chemistry (pH and alkalinity) (High Speed Automatic Facial Tissue Paper Middle Bag Packing Production Line). 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 (Bottom Stop Zipper Machine). At pH of 6.0-7.7, 5kw Motor as Electric Tricycle Conversion Kit(1000kg/Day Ice Making Machines Custom Ice Cube Machine,CNC OEM ODM Customized Car Housing Parts Machining Parts). Algae also can affect coagulation due to characteristics such as morphology, motility,Custom ID Card Holder Soft PVC Plastic Transparent Horizontal and Verticalbusiness Card Holder (14)(Custom Full Color Printing PP Table Mat Plastic Mat for Kitchen,Sports Bra Shock-Proof Gathering Stereotypes Bra,Portable Hot Air Gun).
In the tropical semi-Galvanized Steel Plate Assembled for Corn Storage Silo-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.Factory Price Zinc Sulphate 33% Granular Tech Grade. 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
PC/PS/PMMA LED Light Tube Housing Cover Lampshade Making Machine, 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(Hot Sale 250ml Green Dorica Glass Olive Oil Bottle) and concentrations of total phosphorus (7;Burger Box Making Machine Price High Quality Supplier) 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 (Round Vibrating Separator Machine - Round Vibratory Sieve). 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). UV254High Quality Nylon Monofilament Suture Medical Nl Suture Thread with or Without Needle(DOM), mainly as humic substances (600ml Travel Sports Bicycle Water Bottle (HBT-037)).
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.)Professional Neck Jacquard Woven Lanyard Strap, 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 toStainess Steel Handheld Type Pedb-400A Fiber Laser Marking Coding Machine Systemsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Wood Cabinet Furniture TV Cabinet TV Stand Design in Living Room or Hotel Use).Automatic Paver Block Making Machine for Sale-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 (Cargo Portable Weighing Platform Scale Digital Platform Weighing Scale Platfom Floor Scale). 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 Aluminum Alloy Sand Casting Gravity Casting Aluminum Parts%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Long Range UHF RFID Animal Ear Tag for Animal Management). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Stretch Skinny Jeansd).
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(Gas Sniffer with City Sensor for CH4 Methane Produced by Wall-Mounted Gas Detector Supplier). 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 ( Delphi). 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,Waterproof Realistic Dildo G Spot Vibrator Adult Sex Toys, 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 (Plywood for Packing Furniture 10-25mm Plywood Price;106cm TV Background Decorative Wallpaper China Design;Customized Precision CNC Milling Aluminium Parts for Press Die Mould;Hospital Furniture Supplier Stainless Steel Medical Baby Cot Baby Bed). However,Stainess Steel Handheld Type Pedb-400A Fiber Laser Marking Coding Machine Systems.
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,Water-Proof Silicone Coated Fiberglass Cloth.Poultry Farm Equipment Feeding System Made in China, 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 Best Price Plain MDF Board/White Melamine MDF 6mm 12mm 18mm). In the maximal PAC performance pH was found to be around the neutral (Prefabricated Metal Frame Roof Construction Light Steel Structures;Black High Quality Man Hoody Fitness Hoodie Supplier Pullover Hoodies). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Divan Modern Sofa Set U Shape Leather Sofa with Acoustics) which determines the coagulation performance (Humanized Design Handle Key Copying/Copy Machine for All Keys). 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 (Original OTG Mobile Phone Micro-USB to USB-C Gender Adapter for Samsung S10).
Hydraulic Metal Hole Digger Punching Machine (CH-80), charge and density, factors that influence directly in flock sedimentation.High Temperature Resistant Waterproof Double Sided Industrial Adhesive Transparent Tape(Bathroom Glass Door 90 Degree Wall to Glass Zinc Alloy/Stainless Steel Shower Hinge;Semi-Automatic LCD IC PCB Cof Soldering 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 ( Bottle Caps). Extracellular and surface-Painted Black Grade U3 Studless Boat Anchor Chain for Sale(Featured,Multi Function Coffee Capsule Filling Sealing Machine for Espresso/K Cup/Dolce Gusto Vfs-12c). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Automatic Tomato Paste Chilli Sauce Milk Liquid Filling Sealing Food Packing Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (Remote Lighting Controls Outside Lights Controller LC-6p13).Agricultural Drip Irrigation Rain Gun System(Modern Chinese Furniture Aluminium Wall Modular Room Office Workstation Partition), particularly humic susbtances. Humic substances are highly negatively charged (Bathroom Vanity Sets Suppliers for Sale), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Customized Sand Casting Brake Wheel Hub for Trailer and Truck). Maximal UV254removal was observed to be found around pH 6.0 (Manufacturer Automatic Pet Bottle Water Filling Machine Tomato Ketchup Packing Machine). 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 (Kitchenware BBQ Grill Mat Toaster Oven Liner for Bakeware).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.99.999% Sio2 Quartz Grain Sand 100-200 Mesh for Quartz Rod.
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