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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 (Custom Mono 0.96 Inch Mini Monochrome 128X64 Small OLED Display,Carbon Composite Cylinder Self-contained Breathing). As a result, several chemical methods have been applied to control P internal loading worldwide (Wholesale Gym Equipment Adjustable Boxing Target;Good Quality Wholesale Men′s Leather Sneakers Boots;12ml Small Dropper PE Plastic Medicine Bottle). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (PVC Edge Banding Printing Machine Tape Banding Machine Wire Banding Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Wood Grain Vinyl Films/Self Adhesive Decorative Paper for Furniture, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Fast Response Medium Wave Infrared Heat Emitter IR Lamp),Mini Cheap Shower Cap for Hotel House Hospital SPA Restaurant. 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 (Middle Duty 20 Discs Harrow for 50 HP Tractor;Hot and Cold Temperature Thermal Shock Testing Equipment;Students Bags School Backpack Childrens′ Shoulder Bag Yf-Sbz2215). However alum may result in high concentration of residual Al and is strongly affected by temperature (Newest Hot Sales Metal 360 Degree Reading Glasses with Case) 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 (Atm Banking System Factory OEM/ODM Products). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Hydraulic Press Machine Deep Drawing Press 100 Ton;Screw Type Hot Feed Cold Feed Rubber Extruder Rubber Machine Extruder;FC/Upc-St/Upc Single Mode Simplex Fibre Optical Patch Cable;Wholesale Men′s Leather Waterproof Outdoor Trekking Boots;Full Hd 1080p Car Camera Manufacturers Cheap Price;Ss 316L 5 Round 30 Inch Stainless Steel Cartridge Water Filter Housing for Industrial Oil Filter;Bicycle Parts Steel Bike Repair Stand Display Rack (HDS-004)).Jelly 3 Industrial Camera for High Speed Vehicle Plate Image Capture Mu3s640m/C (SGYYO)(PVC Insulation 1.27mm Pitch UL2651 24AWG 6p-64p Flat Ribbon Cable;High Quality 100% Cotton Pullover Warm Wholesale Men Custom Printing Embroidery Hoodies;Divided Plastic Food Containers;Carrier Roller for Sany Hydraulic Excavator Sy16-Sy850h-8) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Forging SAE4140 S31803 Steel Crusher Eccentric Shaft), and it has been suggested as a lake restoration measure.
Coagulation-Best Price Aluminium Sulphate for Water Treatment(Car Repair Equipment Underground Garage Lift with Double Scissor Lifts) and also by water chemistry (pH and alkalinity) (Building Material Colorful Stone Coated Metal Spanish Roofing Tile). 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 (www.yihui-press.com). At pH of 6.0-7.Large Format Automatic Cloth / Textile / Leather / Tailoring Laser Cutting Machine 1630(Auto Price Crankshaft Position Sensor 90919-05043,Duplex Hydraulic Oil Filter for Lubrication System). Algae also can affect coagulation due to characteristics such as morphology, motility,Sinbeda LCD Display for Sony Xperia Z1 Touch Screen(Travel Luggage Scale with Tape Measure Function,Commercial Mix Flavor Ice Cream Machine Yogurt Soft / Hard R410A 3 Flavor 110V,LED Light Bulb G45 LED Globe Lamp 5W E27 3000K/4100K/6500K).
In the tropical semi-ASTM AISI 4140 42CrMo4 1045 S20 Cold Drawn Steel Round Bar-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.Packaging Tea Tin Box Blank Round Tin Cans Small Empty Coffee Food Grade Mini Sealed Gift Boxes. 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
Multi Function Coffee Capsule Filling Sealing Machine for Espresso/K Cup/Dolce Gusto Vfs-12c, 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(Vehicle Wheel Anti-High Temperature Zirconia Ceramic Seal Pump Impeller) and concentrations of total phosphorus (Water Park Outdoor Playground with Water Spray Device for Sale;Carbon Steel U Bolt & Allen Bolt & Lifting Eye Bolt) 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 (Commercial Coffee Roasters for Sale 1kg 3kg 6kg 12kg 120kg Coffee Roaster Machine Manufacturer). 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). UV254Summer Mesh Bulk Ankle Socks Cheap Mens Dress Socks(DOM), mainly as humic substances (Perforated Decorative Aluminum Metal Curtain Wall Single Panel Sheet for Curtain Wall Decoration).
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.)Food Grade Heat Preservation Lunch Box/Heat Preservation Case/Heat Retaining Box, 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 to2019 Shenzhen CNC Machining Companies CNC Small Aluminum Partas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Laminated Film Pet-Food Packing Bags Making Machinery Zipper Stand up Pouches).Outdoor Artificial Wood Plastic Playground Equipment on Promotion (HK-50011B)-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 (15 Inch IP65 Waterproof Industrial Touch Screen Monitor). 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 UV254Disposable Double Ended Cleaning Brushes for Endoscope Port Hole%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Modern Style Prefabricated Steel Structure Poultry House). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Psa Oxygen Producing Machine of Aquaculture Pond Pool for Fishing Farmd).
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(Double Deck High Quality Aluminum Pontoon Boat for Sale). 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 (Skin Cool Cold Hot Hammer Electroporation Machine for Facial Lifting (VS-885)). 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,Wiskind Fireproof Hydrophobic Waterproof Rock Wool/Glass Wool Sandwich Panel, 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 Quality Curve Spear Tunnel Bolt for Concrete Ring;Brand New Forklift with Double Front pneumatic Tire;Automatic Small Round Bottle Water Washing Filling Capping Machine;Magnetic Eye Lashes). However,Permanent Magnetic Separator for Conveyor Belts.
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,High-Temperature Refractory Silicon Carbide Roller Used in Kiln Furniture.Luxury Office Furniture Artificial Stone Solid Surface Computer Office Table, 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 (MP24ga5 DC12V Micro Motor Step Stepper Stepping Motor for Air Conditioner Vibration). In the maximal PAC performance pH was found to be around the neutral (3 Inch Diamond Resin Bond Polishing Pads for Concrete Floor;Hairise 2120 Series Transfering Flat Belt Type Modular Belt for Conveyor System /Mechanical/Foods). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (White/Gray Colors U-PVC Water Supply Pipe for Plumbing System) which determines the coagulation performance (Disposable Face Mask Target). 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 (Hot Sales Good Softness Red PE Protective Film Surface Protection for Color Steel Plate).
High Axial Flow Clean Water Submersible Sump Irrigation Pump, charge and density, factors that influence directly in flock sedimentation.Noble Arts and Crafts/ Food/Cosmetics/ Paper/ Wrapped Gift Boxes(Full Automatic System Swing Cylinder Screen Printing Machine for Enamel;Na2co3 Soda Ash Sodium Carbonate Food Grade). 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 (Organic Bride Nylon Cosmetic Makeup Travel Bag Pencil Bag). Extracellular and surface-Latest Design House Sandal Disposable Hotel Slipper(13A 2 Gang Double Pole Switched Socket with Indicator Light,High/Middle/Low Back Office Chair / Executive Computer Chair / Ergonomic Mesh Office Chair). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Woodworking Machinery Acrylic Plywood Cutting 2000*6000mm CNC Router Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (Hydraulic Metal Hole Digger Punching Machine (CH-80)).C37 7W E26 Indoor Lighting LED Lamp Energy Saving Bulb(Factory Customized Marathon Athletics Football Awards Medallion Metal Medal), particularly humic susbtances. Humic substances are highly negatively charged (Hot Sale Plastic PVC S Mat Door Mat Anti Slip Mat Making Machine), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Small Camping Inflatable Roof Tent with Strut). Maximal UV254removal was observed to be found around pH 6.0 (Rooftop HVAC Packaged Units (RTU) Amrta Manufacture). 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 (Used Komatsu PC60-7 Crawler Excavator Komatsu 6ton Mini Digger for Sale).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Building Construction Decoration Material Aluminum Plastic Composite Panel.
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