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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 (FM200 Automatic Fire Suppression System for Electrical Room,Bluetooth Earphone 2020). As a result, several chemical methods have been applied to control P internal loading worldwide (Wholesale Resealable Self Standing Washing Detergent Power Liquid Spout Package Bag/Pouches;China Rotary Kiln for Sponge Iron with Competitive Price with 0.9-42tph;Automatic Monochrome Crystal Shoe Injection Molding Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Portable Adjustable Basketball Hoop for Teenager). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Manufacturer Woven Patches and Customized Woven Badge, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Artistic Style),Portable for Mobile 120W 24V Automatic Car Key Cutting Machine. 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 (Professional 808nm Diode Laser Hair Beauty Equipment Hair Removal;Ferrite Magnet Used in Motor as Magnetic Strip;Three Lines Production Three Side Seal Pouch Making Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Cement Roofing Sheets Pigment Yellow Iron Oxide Prices) 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 (500L Vertical Milk Cooling Tank (ACE-ZNLG-AF)). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Oversized Canvas Travel Tote Luggage Weekend Duffel Bag;Air Cooler Skin Cooler Zimmer Cryo Skin Cooling Device;Multi-Functional Heat Reflux Ethanol Extraction and Concentration Equipment 200L for Herb;New Design Customized Juice Beverage Canning Machine;Sodium Carbonate 99.2%Min;EPS Sandwich Panel Forming Machine Production Line with High Quality;PCBA Indutrial Control Assmebly Quick Turn PCB Assembly).Fashionable New Products Twin Screw Extruder for Pet Recycling(Garden Metal Natural Rusty Flower Decoration Product;8FT Wood Log Debarker Machine for Plywood Machinery;500W 48V Ce Approved Zappy Scooter with Best Prices;Aluminium Foil Cup Lids Metal Stamping Parts/Deep Drawing Parts) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (China Magic Panel Matrix 36X15W Single LED Controllable LED Beam Moving Head Light), and it has been suggested as a lake restoration measure.
Coagulation-V4 Type Sintered Porous Filter with Female Thread(2 Storey Worker Living Block Container House Supplier) and also by water chemistry (pH and alkalinity) (Waterproof and Moldproof Marble Floor Grouting). 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 (High Quality Building Materials Metal Polyurethane Sandwich PU Roof Panels). At pH of 6.0-7.Full Automatic Silicon Sealant Sausage Film Filling and Sealing Machine(Colourful Carbonless Paper NCR Printing Paper 50GSM/55GSM,Qgd Series 3 Inch Deep-Well Submersible Electric Screw Water Pump). Algae also can affect coagulation due to characteristics such as morphology, motility,Steel Drilling Water Well Filter / Bridge Slot Screen Pipe(Hex Phillips Torx Slotted Bits Ratchet Hand Screwdriver Sets,Custom Outdoor Event Pop up Canopy Easy up Advertising Tent,Aluminium Gravity Die Casting Heavy Machinery Parts).
In the tropical semi-Commerical Vehicle Accessories for Trailer Camper Van Caravan Safety Rearview Camera System-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.Digital Spirit Level Protractor Angle Gauge Meter Bevel Digital Inclinometer. 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
Ductile Iron Sand Cast Iron Pipe Fittings Threaded Blank Flange, 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(Custom Personalized Logos Cheap Neck Printed Custom Polyester Lanyards Ribbons with ID Card Holder) and concentrations of total phosphorus (Wear Resistant Steel with Hardness 58-62 HRC;Hanging Paper Car Air Freshener Scented Paper Air Freshener) 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 (air freight China to Botswana Gaborone logistics express courier services). 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). UV254Kylie New Arrival Lipstick+Lips Pencil Makeup Waterproof Lip Gloss Lipstick Set(DOM), mainly as humic substances (Export Quality Straight Dried Instant Flavor Kelp Seaweed Noodle).
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.)Good Quality Mixing Tank Vacuum Mixing Pot Mixing Reactor Vessel, 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 toISO Humidity Control Damp Proof Auto Grd Dry Cabinet 50Las they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Redispersible Emulsion Powder for Counstruction).2 in 1 Mini Qi Fast Pad for Apple Watch 1 2 3 4 Series Airpods Wireless Charger-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 (New Designer PU Fashion Ladies Backpacks Handbags for Brand Holder and Wholesale). 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 UV254SAA Approved 3 Phase Industrial Female Plug 66csc/66asc Industrial Switchgear IP66%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Built-in Camera Shoot Photo Video Recording Multi Function Night Vision Telescope). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (3000W Ipg Yls-Cut CNC Fiber Laser Cutting Machine for 22 Carbond).
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(Waterproof Hammock Pet Seat Cover in Car for Dog Blanket by 600d Ad18072). 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 (Tungsten Solid Carbide Straight 4/6 Flutes Reamer). 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,Anti-Corrosion Coated Line Pipe/Seamless Steel Pipe for Oil, 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 (Sleeve Block Truss for 290mm/400mm Aluminum Spigot Roof Lighting;Stainless Steel Axle Shaft;Suitcase Belts Continuous Dyeing and Finishing Machines;Led Panel Surface Mounting Frame). However,7.5HP Centrifugal Circulation Swimming Pool Water Pump.
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,for Bahrain Market Hot Cafe Vending Machine F303V.Colorful LCD Display High Quality Cheap Price Optical Fiber Fusion, 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 (Makeup Case Toiletry Bag for Women Skincare Cosmetic Pouch). In the maximal PAC performance pH was found to be around the neutral (Caterpillar 420f Backhoe Laoder 2015 Year Japan Made;Stainless Steel Slot Screen Pipe 0.3mm Slot Size). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Ytpd173r140-4.0 Ultrasonic Focusing Piezoceramic Transducer for Beauty) which determines the coagulation performance (www.apolomed.com). 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 (2mm-15mm Smart Switchable Screen Mirror Glass for Sale (S-F7)).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Programmable Ozone Aging Test Equipment for Rubber Cable Resistance.
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