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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 (Oversized Canvas Travel Tote Luggage Weekend Duffel Bag,800n Lift Support Strut). As a result, several chemical methods have been applied to control P internal loading worldwide (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). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (EPS Sandwich Panel Forming Machine Production Line with High Quality). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Wholesale Oil Tanker Trailer 3 Axle 42000L Trailer Fuel Tank Semi Truck Trailer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (2.4g Wireless Usb Receiver),Fat Tire City Coco Electric Bicycle Motorcycl Bike Electric Scooter for Adult. 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 (PCBA Indutrial Control Assmebly Quick Turn PCB Assembly;Garden Metal Natural Rusty Flower Decoration Product;8FT Wood Log Debarker Machine for Plywood Machinery). However alum may result in high concentration of residual Al and is strongly affected by temperature (Aluminium Foil Cup Lids Metal Stamping Parts/Deep Drawing Parts) 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 (Tmf6 Linear Block for Linear Palletizer Full Closed). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (China Magic Panel Matrix 36X15W Single LED Controllable LED Beam Moving Head Light;2 Storey Worker Living Block Container House Supplier;Waterproof and Moldproof Marble Floor Grouting;Colourful Carbonless Paper NCR Printing Paper 50GSM/55GSM;Blank Jcop Card High Quality Supplier;Qgd Series 3 Inch Deep-Well Submersible Electric Screw Water Pump;Hex Phillips Torx Slotted Bits Ratchet Hand Screwdriver Sets).Medical Equipment One Step Tp Device Syphilis Rapid Test Kit(Custom Outdoor Event Pop up Canopy Easy up Advertising Tent;High Quality Folding Training Study Table with Wheels Sf-10f;Fish Net Needle Machine;Glow in The Dark Pigment Luminescent Luminous Powder) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Custom Personalized Logos Cheap Neck Printed Custom Polyester Lanyards Ribbons with ID Card Holder), and it has been suggested as a lake restoration measure.
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In the tropical semi-OEM Customized Design Heat Transfer Print Sports Baseball Cap Manufacturer-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.European VDE Schuko 3-Pin Waterproof IP44 Power Plug. 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 Most Industrial Outdoor Trampoline, Commercial Trampoline Park for Sale, 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(ISO Humidity Control Damp Proof Auto Grd Dry Cabinet 50L) and concentrations of total phosphorus (Wholesale Factory Prices Ceramic Hair Curler Magic Hair Curler;201 301 304 Embossed Checkered Plate Stainless Steel Coil/Sheet) 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 (Built-in Camera Shoot Photo Video Recording Multi Function Night Vision Telescope). 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). UV25412.5/80-18 16.9-24 16.9-28 Agriculture Backhoe Loader Tires(DOM), mainly as humic substances (High Quality Sky Indoor Mesh Trampoline Zone Park with Cheap Prices).
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.)China Supplier Customized Polish Storage Wall Mounted Wine Rack, 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 to7as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(UL Ce 2.4W 24V 30LEDs 2700K 3528 1210 Flexible Strip LED).Customized Waterproof Backpack Canvas Laptop Bag-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 (Suitcase Belts Continuous Dyeing and Finishing Machines). 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 UV25475 Inch LCD Smart Interactive Whiteboard Touch Screen with 4K Screen Display%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Makeup Case Toiletry Bag for Women Skincare Cosmetic Pouch). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Al2O3 15~22% Alumina Inert Ceramic Balls for CO2 Degassing Towerd).
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(Stainless Steel Slot Screen Pipe 0.3mm Slot Size). 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 (Ytpd173r140-4.0 Ultrasonic Focusing Piezoceramic Transducer for Beauty). 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,Square Home Sofa Throw Decorative Pillow Case Cushion Cover, 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 (Rectangle Custom Various Color Metal Label Tag Sticker Handbag/Luggage Hardware;Customized CNC Machining Checking Fixture for Automotive Bracket;PS Foam Food Container Production Line PS Lunch Box Forming Machine;Auto Flexo Printer Printing Cutting Packing Packaging Corrugated Carton Making Machine). However,Stage LED Bar 54PCS*3W RGBW DJ Disco Stage Lights.
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,Adjustable for Home Appliance Bimetal Temperature Regulator Kst Thermostat.Valve Wheel Adjustable Hydraulic Impact Torque Wrench, 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 (Customized Precision CNC Mechanical Parts with Steel). In the maximal PAC performance pH was found to be around the neutral (China Products/Suppliers. Prefabricated Metal Shed Steel Structure;Outdoor LED Street Pole Advertising Business Double Sided LED Signs). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (HD Small Pixel Pitch Full Color P1.667 Indoor LED Display for Meeting Room) which determines the coagulation performance (Cast Parts High Quality Supplier). 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 (Ventilation Back Draught Damper Volume Control Damper One Way Shutter Actuators).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Eco Brava Small Mud Interlock Brick Press Machine.
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