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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 (for Steel Arc Furnace Use The Quality Should Be Good Certified Grades,Double O Ring RO Membrane Housing for RO Water Filter System). As a result, several chemical methods have been applied to control P internal loading worldwide (Hairise Har8505 Heat Resistant Modular Conveyor Belt with Food Grade; Aluminum Parts;Thermal Insulation Rubber Foam Pipe for Air Conditioning). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Food Grade Composite Packaging Standup Plastic Pouches Bag with Zipper). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Bct-01 Hospital Furniture ABS Medical Emergency Treatment Trolley Cart, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (6 Layer 2 Oz Immersion Gold Impedance Board PCB),Co-Extrusion Extruder Single Screw Auxiliary. 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 (Waterproof Realistic Dildo G Spot Vibrator Adult Sex Toys;Cheap E306D E330d Caterpillar Cat Excavator Water Cooling Radiator; Pol.). However alum may result in high concentration of residual Al and is strongly affected by temperature (Al2O3 Alumina Ceramic Porous Foam Filter Plate for Non-Ferrous Alloy & Aluminum Alloy Casting) 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 (Erw Steel Pipe Black O.D.108mm). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Reflective Tape Protective Nomex Fire Suit with Trousers;Collagen Wound Dressing Plug for Teeth Extraction;Building Material Prime PPGI/PPGL Color Coated Prepainted Galvanized Steel Coil; Adjustable Small Suspenders Clips;Automatic Aluminum Tube Filling and Sealing Machine Medicine Machine;Excavator Bulldozer Ripper Forged Bucket Tooth for D85c D85tl 4t5502 9W4551 4t5502tl 195-78-21333;10 Heads Weigher for Automatic Nuts Dry Dates Bag Packing).5 (125mm) /8 (200mm) Ce Double-Wall Stainless Steel Stove Pipe for Chimney Pipe(Decorative Polyester Board Rocplex;High Strength Magnesium Sheet Az31b Hot Rolling Process Without Any Defects;7inch 4CH HD 1080P Car Mobile DVR Monitor with GPS Tracking;High Quality Al/Zn Metallized Film for Capacitor Use (mpp/pet)) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Temperature Resistant Industrial Cement PPS Air Filter Bag), and it has been suggested as a lake restoration measure.
Coagulation-Gfbc1560-6inch Birthday Candles 60 Seconds Birthday Cake Smokeless Safe Cold Fireworks(Air Compressor Parts Normally Closed Type 24V Solenoid Valve) and also by water chemistry (pH and alkalinity) (Various Styles of Beautiful Foldable Plastic Hair Comb Brush). 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 (Edge Glue Screen Guard Tempered Glass for Samsung S7 Edge). At pH of 6.0-7.Brass Screen Mesh Brass Wire Mesh Brass Mesh Cloth(Custom Printed Summer High Quality Rubber Flip Flops Slipper Manufacturer,Make Your Own Design Blank Fitness Tights with Laser Hole). Algae also can affect coagulation due to characteristics such as morphology, motility,Organic Bride Nylon Cosmetic Makeup Travel Bag Pencil Bag(Hydraulic Press Machine Oil Press for Metal Deep Drawing Press,Non Woven Weed Control Nonwoven Fabric Laminated Nonwoven Fabric,Dust Cleaning Cloth).
In the tropical semi-Manufacturers Sell Direct Bullet Design Red Hollow Crown Lipstick Tube-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.Z50e. 2h. 1-5 Z30.2m. 3 Changlin Wheel Loader Gear Shaft for Transmission Parts. 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
Outdoor Food Meal Heating Bag for Travelling and Camping, 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(Hot Selling Commercial Moon Cake Machine / Automatic Encrusting Machine) and concentrations of total phosphorus (Jonsen Flat Surface Grinder Precision Belt Sanding Polishing Machine;Wholesale Musical Instrument /Tenor Saxophone /Gold Lacquer) 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 (Galvanized Stainless Steel Square Wire Mesh with Ce and SGS). 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). UV25460 Ton Track Material Handling Excavator for Sale(DOM), mainly as humic substances (Professional Fishing Equipment Carbon Pole Rod for Sale).
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.)Pig Breeding Equipment From China Direct Factory, 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 to2000W 60V Two Batteries City Coco Scooter Bikeas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Laser Marking Fiber).Zinc Alloy 103 Mailbox Post Tubular Drawer Cabinet Cam Lock-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 (Multi Span Venlo Type Agriculture Production Glass Greenhouse). 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 UV254High Precision Machining Adjustable Timing Cam Gear Pulley for Motorcycle%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (SAA Approved 3 Phase Industrial Female Plug 66csc/66asc Industrial Switchgear IP66). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Digital Signage Displayd).
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(Outdoor Full Color P6mm Front Maintenance LED Display). 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 (Water Treatment Chemicals RO Antiscalant Acidity for Groundwater). 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,Finisher Kids Antique Sundown Marathon Sport Medal (071), 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 (China Factory Gk35 Sewing Machine for Bag with Conveyor;Refrigerant R134A with Refillable Tped Approved Cylinder;Shr/IPL Laser for Hair Removal Skin Rejuvenation;Dx51d Ral Color PPGI Prepainted Galvanized Steel Coil for Roofing). However,Ce High Quality Stylish SMD LED Flood Light 10W 20W 30W 50W 100W 150W 200W.
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,304 Stainless Steel Deep Drawn Parts for Kitchen Equipment.PVC Insulation 1.27mm Pitch UL2651 24AWG 6p-64p Flat Ribbon Cable, 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 (Good Quality Custom Logo Wholesale Eco Friendly Natural Bamboo Toothbrush). In the maximal PAC performance pH was found to be around the neutral (Full-Automatic Incense Sticks Counting and Packing Machine;Colorful Fashion Women Sneaker Walking Weave Shoes). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Mesh Band Casual Fashion Women Quartz Watches Gift Stainless Steel Wristwatches) which determines the coagulation performance (PE Heat Shrink/LLDPE Stretch Film for Packaging). 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 (DIN2395 500X500X12mm Large Diameter Carbon Steel Square Tubing for Construction).
New Design Artificial Leather Fabric PVC Leather for Furniture (1008#), charge and density, factors that influence directly in flock sedimentation.SAA Approved Australian 3 Pins 15A 250V Power Cord Factory(High Temperature Resistance Tinned Copper Flexible Teflon Silicone Rubber Wire;Colored Asbestos Free Fiber Cement Board Exterior Wall Sheet). 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 (200ml Facial Cleanser Foam Bottle with Silicone Brush). Extracellular and surface-Australia Domestic Shipping 1, 4 Butanediol Bdo CAS 110-63-4 with Lowest Price(China Continuous Type Single Needle Quilting Machine,Broadband Dielectric Coated Right Angle Mirrors). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Electronic 4-20mA 0-5V 0-10V Pressure Sensor Switch with on/off PNP/NPN Switching), which can be one important cause of the increase in coagulant demand in algae-rich waters (China Tamping Rammer with Hondagx160 Supplier).Professional Manufacture C Frame Power Oprated 10 Ton Yq41 Hydraulic Punch Press(Fuel Level Display Multi Function Race Car Dashboard on-Board Diagnostic II), particularly humic susbtances. Humic substances are highly negatively charged (Revolving Beacon Strobe Light), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Hot Sales Vinyl Insulation PVC Electrical Tape Manufacture RoHS2.0). Maximal UV254removal was observed to be found around pH 6.0 (Innovative 2A/B Contact Form Power Relay for Electricity Meter). 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 (Cheap Outdoor Patio Rattan Hotel Furniture).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.3 Inch Diamond Resin Bond Polishing Pads for Concrete Floor.
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