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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 (Heavy Duty Galvanized Stacking Steel Pallet Shelving with Posts,m.bestcontactor.com). As a result, several chemical methods have been applied to control P internal loading worldwide (Potato Chips Design Non-Toxic Silicone Baby Teether Toy;Duosida Quick Female Plug Connector Type 1 CCS Combo 1 Fast DC EV Charging Plug;JAC 4X2 3ton 5ton Refrigeration Truck Freezer Box Truck). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (OEM Stamping Parts Aluminum Profile Stamping for Child Safety Seats). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Lx85-9m Wheeled Digger Digging Height 6536mm 8 Ton Mini Wheel Wood Grabber, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (3DTALK DS200 Metal Frame Dental 3D Printer For Digital Dental Solution),Fast Inflatable Air Bag Sofa Lounge Lazy Chair Bag Camping Bed Beach Hangout. 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 (Automatic Fresh Fruit Juice Bottle Natural Fruit Canning Machine;Aluminum Motor Housing Used in The Electromotor / Electric Motor Industry;High Quality Medical Disposable Pen Type Blood Collection Needle). However alum may result in high concentration of residual Al and is strongly affected by temperature (Multifunctional RF/40K Body Vacuum Roller Weight Loss Beauty Salon Cavitation Beauty Equipment) 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 (Camera Lens Storage Suppliers for Sale). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Full Automatically Wp Line Powder Jet Mill Micronizer in Agriculture Field;Professional Super-Automatic Tyre Changer Without Lever;Plastic PE HDPE LLDPE LDPE Irrigation Water High Speed Pipe Extruder Making Machines;Power Transformer Voltage Transformer Pq2620 Series High Frequency Transformer;Fire Protection Mask Fire Escape Hood Gas Mask;Exdiibt4 Explosion Proof Type 10kw Power Inverter Built in Low Frequency Transformer;Stainless Steel Sanitary Pipeline Three-Stage Emulsion Mixing Pump).Factory Price Luxury Autism Heavy Duty Weighted Mink Blanket(American Double Hung Thermal Break Aluminum Window in China;Best Industrial Coal Fired Steam Boiler Manufacturer in China;Greenhouse Hydroponics Equipment for Agriculture Soil Less Cultivation;7 Colorful 240 Degree Wide Lens Mini Speaker Smart WiFi Camera of Night Light Wc001y13) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (18X18 Asian Black Iron Square Tube/Black Square Steel Pipe Seamless), and it has been suggested as a lake restoration measure.
Coagulation-100% Fabric Advertising Display See Through Mesh Banner Windproof(Luxury Modern Bathroom Furniture Sanitary Ware Solid Surface Basin) and also by water chemistry (pH and alkalinity) (Monofilament Fishing Tackle Green Nylon Fish Net). 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 (Oem Flat Head Nail). At pH of 6.0-7.Black Window Gable Boxes, 17*11*7cm Wedding/Baby Shower Favor Gift Box, Muffin Pastry Box(Used Fashion Summer Children′s Dress Unsorted,Longboard or Skateboard Ball Bearings 608zz 608-2RS). Algae also can affect coagulation due to characteristics such as morphology, motility,100mm Thickness China Roof/Wall EPS Sandwich Panel From China Suppliers(High Speed Automatic Facial Tissue Paper Middle Bag Packing Production Line,1000kg/Day Ice Making Machines Custom Ice Cube Machine,Tempered Glass Insulating Glass Cutting Table Glass CNC Machine).
In the tropical semi-Stainless Steel Rectangular Pipes for Balcony Guardrail-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.Jbz-22D Automatic High Speed Paper Cup Forming 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
10W Auto Oval Work Car Light Blue Red LED Forklift Warning Head Lamps, 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(Sports Bra Shock-Proof Gathering Stereotypes Bra) and concentrations of total phosphorus (2000W 10mm Stainless Steel Mild Steel Fiber Laser Cutting Machine Price;Aluminium Degassing) 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 (7). 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). UV254Flexible Plastic (PVC) Sheet with RoHS Standards (1mm-10mm)(DOM), mainly as humic substances (Factory Stocked 500ml Double Wall Plastic Glitter Water Bottle Diamond Lid Insert Layer).
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.)Customized Mining Equipment with Drawing Design, 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 toShielded Mini Ball Bearings with Anti-Rusty Stainless Steel Smr106zzas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Car Seat Cell Phone Holder).Custom Jewellery 925 Sterling Silver Jewelry Diamond Stud Earrings-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 (Stainess Steel Handheld Type Pedb-400A Fiber Laser Marking Coding Machine Systems). 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 UV254Food Quick Freezing Machine Type Industrial Freezer IQF Fruit Freezing Tunnels%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Frosted White Grey Blue Painted Glass Candle Jar with Wood Lid). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Household Small Manual Cbd Oil Extracting Machined).
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(Cargo Portable Weighing Platform Scale Digital Platform Weighing Scale Platfom Floor Scale). 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 (Long Range UHF RFID Animal Ear Tag for Animal Management). 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,Hight Quality Air Filter C1250 for Mann and Atlas Air Compress, 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 ( Delphi;Combination Lock Protect Weed Smoking Accessories in Black or Customization Hot Sale Bag Backpack;Meat Processing Cooling Flake Ice Making Machine (Shanghai Factory);Tradional Chinese Herbs Supplier). However,Industrial Paraffin Wax/Powder/Slab/Paraffin Wax Chemical Formula.
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,Tri-Axle 50tons 60tons 18m Low Loader Lowbed Trailer Axles.Colorful Mobile Phone Accessory Dull Polish Back Cover PC Phone Case for Meizu Note 6, 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 (Plywood for Packing Furniture 10-25mm Plywood Price). In the maximal PAC performance pH was found to be around the neutral (106cm TV Background Decorative Wallpaper China Design;Customized Precision CNC Milling Aluminium Parts for Press Die Mould). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (China Best Price Plain MDF Board/White Melamine MDF 6mm 12mm 18mm) which determines the coagulation performance (Different AWG Size Customized High Temperature Cable PTFE Electric Wire). 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 (Prefabricated Metal Frame Roof Construction Light Steel Structures).
Women′s Mesh Contrast Pleat Fashion Black Tank Top, charge and density, factors that influence directly in flock sedimentation.Folding Pile Driver Machine with Hydraulic Power(Black High Quality Man Hoody Fitness Hoodie Supplier Pullover Hoodies;Divan Modern Sofa Set U Shape Leather Sofa with Acoustics). 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 (Original OTG Mobile Phone Micro-USB to USB-C Gender Adapter for Samsung S10). Extracellular and surface-Compatible for Nellcor/Neusoft Reusable SpO2 Sensor Adult/Neonatal Finger Clip SpO2 Sensor(High Quality SMC FRP Watertight Waterproof Manhole Cover BS En124,Bathroom Glass Door 90 Degree Wall to Glass Zinc Alloy/Stainless Steel Shower Hinge). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Semi-Automatic LCD IC PCB Cof Soldering Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters ( Bottle Caps).Bottle/Cup Electrical Tunnel/ Steam Tunnel for Shrinking Sleeve Labeling Machine(Multi Function Coffee Capsule Filling Sealing Machine for Espresso/K Cup/Dolce Gusto Vfs-12c), particularly humic susbtances. Humic substances are highly negatively charged (Medical Bathroom Safety Rotatable Swivel Seat Shower Bath Chair), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Automatic Tomato Paste Chilli Sauce Milk Liquid Filling Sealing Food Packing Machine). Maximal UV254removal was observed to be found around pH 6.0 (Remote Lighting Controls Outside Lights Controller LC-6p13). 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 (Modern Chinese Furniture Aluminium Wall Modular Room Office Workstation Partition).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Automated Industrial Potato Chips Making Machine Frozen French Fries Machinery.
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