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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 (Portable Adjustable Basketball Hoop for Teenager,Baode Lights Outdoor 5m20W Solar Street LED Lighting Supplier). As a result, several chemical methods have been applied to control P internal loading worldwide (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). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Cement Roofing Sheets Pigment Yellow Iron Oxide Prices). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Non Woven Wheel for Stainless Steel Polishing and Grinding, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Factory Price Wireless Bluetooth Audio Transmitter Module for Headphone),30cm Round Clear Plastic Pot Plant Trolley. 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 (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). However alum may result in high concentration of residual Al and is strongly affected by temperature (New Design Customized Juice Beverage Canning Machine) 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 (Amino Acid Ganules Making Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (EPS Sandwich Panel Forming Machine Production Line with High Quality;PCBA Indutrial Control Assmebly Quick Turn PCB Assembly;Garden Metal Natural Rusty Flower Decoration Product;8FT Wood Log Debarker Machine for Plywood Machinery;m.thyaohua.com;Aluminium Foil Cup Lids Metal Stamping Parts/Deep Drawing Parts;China Magic Panel Matrix 36X15W Single LED Controllable LED Beam Moving Head Light).Decorative Waterproof Fireproof Heat Resistant HPL High Pressure Compact Phenolic Laminate Board(2 Storey Worker Living Block Container House Supplier;Waterproof and Moldproof Marble Floor Grouting;dead burned magnesia;Colourful Carbonless Paper NCR Printing Paper 50GSM/55GSM) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Qgd Series 3 Inch Deep-Well Submersible Electric Screw Water Pump), and it has been suggested as a lake restoration measure.
Coagulation-Solar LED Highway Emergency Warning Beacon for Traffic Safety Solution(Hex Phillips Torx Slotted Bits Ratchet Hand Screwdriver Sets) and also by water chemistry (pH and alkalinity) (Custom Outdoor Event Pop up Canopy Easy up Advertising Tent). 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 (100% Pure Copper Scrubber Cookware Cleaning of Chore Boy Z Boy). At pH of 6.0-7.AL926C Tractor Wheel Loader with Extreme Long Arm 4500mm Dumping Height for Sale(High Quality Folding Training Study Table with Wheels Sf-10f,Glow in The Dark Pigment Luminescent Luminous Powder). Algae also can affect coagulation due to characteristics such as morphology, motility,Secondhand Backhoe Loader Caterpillar 416e Excavator Loader Original for Sale(Custom Personalized Logos Cheap Neck Printed Custom Polyester Lanyards Ribbons with ID Card Holder,Wear Resistant Steel with Hardness 58-62 HRC,Butaphosphan And B12 Injection 2.5% For Animal Treatment).
In the tropical semi-PCB Mounting Shielded Modular Jack Ethernet RJ45 Connector-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.ODM Customized Black Anodized AISI304 Stainless Steel CNC Machined 12mm Axle Washer (S-120). 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
Musk Ambrette Yellow Lump for Daily Flavor and Perfume Making, 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(air freight China to Botswana Gaborone logistics express courier services) and concentrations of total phosphorus (Export Quality Straight Dried Instant Flavor Kelp Seaweed Noodle;Best Dental Chair) 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 (Height Adjustable Removable Foldable Feeding Baby High Chair). 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). UV254Hcd600 RF Wireless Remote Control Duplicator Machine for Locksmith(DOM), mainly as humic substances (ISO Humidity Control Damp Proof Auto Grd Dry Cabinet 50L).
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.)100% Pure PC Suitcase Luggage Aluminum Trolley Bags for Travel, 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 toBuilt-in Camera Shoot Photo Video Recording Multi Function Night Vision Telescopeas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Cufflinks).ATV Electric Winch with 3500lb Pulling Capacity (Star Model)-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 (Tungsten Solid Carbide Straight 4/6 Flutes Reamer). 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 UV254Shenzhen Customized Fr4 FPC Flexible Circuit Board Customized PCB Manufacturing PCB%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Custom Industrial Field Block Ferrite Rare Earth Magnet). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (China Boride powderd).
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(Sleeve Block Truss for 290mm/400mm Aluminum Spigot Roof Lighting). 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 (Stainless Steel Axle Shaft). 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,Professional Manufacturer NPT Thread Dustproof Nylon Cable Gland / Plastic Cable Gland, 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 (Caterpillar 420f Backhoe Laoder 2015 Year Japan Made;Stainless Steel Slot Screen Pipe 0.3mm Slot Size;Ytpd173r140-4.0 Ultrasonic Focusing Piezoceramic Transducer for Beauty;420 Type Nitrogen Flushing Thermoforming Packing Machine). However,Home Decorative Universal Electric Fireplace with Remote Control and LED Flame.
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,2018 Amusement Park Children Outdoor Playground Equipment for School (HS806001).4 Inch Cast Iron Wafer Pneumatic Butterfly Valve, 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 (2mm-15mm Smart Switchable Screen Mirror Glass for Sale (S-F7)). In the maximal PAC performance pH was found to be around the neutral (220kv Composite Suspension Insulators for Transmission and Distribution Line;Rectangle Custom Various Color Metal Label Tag Sticker Handbag/Luggage Hardware). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Customized CNC Machining Checking Fixture for Automotive Bracket) which determines the coagulation performance (Home Care OLED Display Portable Fingertip Pulse Oximeter). 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 (PS Foam Food Container Production Line PS Lunch Box Forming Machine).
Wns Gas Oil Fired Boiler Hot Water Heating System, charge and density, factors that influence directly in flock sedimentation.China Suppliers Factory Paper Machine Industrial Ss Cylinder Mould(Customized Precision CNC Mechanical Parts with Steel;China Products/Suppliers. Prefabricated Metal Shed Steel Structure). 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 (Outdoor LED Street Pole Advertising Business Double Sided LED Signs). Extracellular and surface-SS304 SS316 St2.9 St4.8 DIN7981 Stainless Steel Cross Recessed Pan Head Self Tapping Screws(Cnc Production Machining Part,HD Small Pixel Pitch Full Color P1.667 Indoor LED Display for Meeting Room). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Ventilation Back Draught Damper Volume Control Damper One Way Shutter Actuators), which can be one important cause of the increase in coagulant demand in algae-rich waters (Hand Tools Mini Wire Brush Set for Construction 3PCS OEM).Commode, Foldable, Wheelchair, Detachable Parts (YJ-016B)(Food Grade Titanium Dioxide F-200 Pigment), particularly humic susbtances. Humic substances are highly negatively charged (Wholesale Exporter China Supplier Stainless Steel Checker Plates From Foshan), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Silicone Rubber Pin Insulator/Polymer Composite Insulator (10kv-33kv)). Maximal UV254removal was observed to be found around pH 6.0 (Customized Waterproof Backpack Canvas Laptop Bag). 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 (Medical Acupoint Patch with Sterile Wound Patch for All People).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Custom Your Design Logo Women T Shirt Fashion Cotton Casual Girl Tshirt Basic Ladies T-Shirt.
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