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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 (Refrigeration Air Conditioner 18000 BTU 2HP Compressor Malaysia Panasonic 2js324D,Fst200-201 Digital 4-20mA 3 Cup Anemometer Wind Speed Sensor). As a result, several chemical methods have been applied to control P internal loading worldwide (Recoil Steel Hot Coiled Extension Coil Compression Heavy Duty Spring; IPS 720*1520 Display Android 9.0;Auto Car Parts Good Quality 16620-0s010 Tensioner Pulley). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Women′s Stretchy Yoga Training Mesh Leggings with Side Pocket). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,2800X8000mm ASME Certified Rubber Vulcanizating Chamber (SN-LHGR2880), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (1550nm Skin Rejuvenation),2 in 1 Baby Feeding Chair Kids Eating High Chair. 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 (Wholesale Promotional Children Painting Apron;Poultry Farming Automatic Chicken Feeding Pan System;600W Mini Lathe Metalworking 7 X 14 Tool Turning Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Custom High Quality Clear BOPP Adhesive Tape for Carton Sealing) 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 (Outdoor P10 Advertising Video Wall Screen Module LED Displays/ Digital Sign). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Automatic Concrete Paving Interlocking Block Brick Making Machine;OEM Custom Cotton Twill Flat Top Military Army Hat and Cap;Wood Grain Vinyl Films/Self Adhesive Decorative Paper for Furniture;Attractive Kids Trampoline Park for Jump Baby Indoor Soft Play Equipment Theme Parks for Sale;Light Type Electrode Holders;Fish Scale Shaped Waterproof Roof Tile for Roof Tile;Hydraulic Control Valve-100A Angular Stable Water Level Valve).Lifting and Hoisting Industrial Manual Chain Lever Block Vt(Direct Thermal Label with Premium Quality Adhesive Sticker Label;Wholesale Room Ozone Generator for Fruits and Vegetables;Tempered Laminated Glass;Folding Dinner Table Set in Dining Room Furniture) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Agricultural Low Cost Greenhouse Farming Equipment), and it has been suggested as a lake restoration measure.
Coagulation-Galvanized Pullet Chicken Cage Baby Chicken Cages(Anti-Slip Crazy christmas Cute Funky Cotton Custom Socks) and also by water chemistry (pH and alkalinity) (Patterned Shoulder Nozzle Aluminum Tube for Glue/Medical Ointment Packaging). 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 (Furniture Upholstered Dining Chair for Restaurant). At pH of 6.0-7.Industrial Die Temperature Extrusion Refrigerant Unit with Phase Sequence Protection(Light Steel Frame Cheap Prefabricated Houses for Sale From China,Eco-Friendly Material Restaurant Furniture Metal Stainless Steel Desk Leg Table Base Legs (TB-04)). Algae also can affect coagulation due to characteristics such as morphology, motility,Customized Full Series Extruded Aluminum Profile for Kitchen(Fsi 5kw 24VDC Pure Sine Wave Hybrid PV Solar Inverter with High Efficiency MPPT Controller,Mobile Phone Jammer + WiFi / GPS / 4G Jammer 6 Bands,250ml/500ml/1000ml Transparent Round Glass Storage Honey Jar with Tin Lid).
In the tropical semi-Stainless Steel Short Pitch Precision Single Roller Chain (B series)-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.18mm Red/Black/Dynea Film Faced Marine Plywood Construction Building Material. 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
Chinese 1kw Vertical Axis Wind Turbine for Home Use, 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(Bamboo Rattan Stick / Aroma Rattan Stick/Nature Reed Rattan Stick) and concentrations of total phosphorus (Customized Wholesale Waterproof Crossbody Chest Bag Backpack Sling Bag Women Messager Shoulder Bag;Ash Basalt Sticks Mosaic Manufacturers Cheap Price) 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 (Butterfly Pn16 CF8m Water Dual Flap Flapper Type Wafer Check Valve). 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). UV254Ce RoHS Approval 12W LED Lamp Bulb with Aluminum PBT Plastic(DOM), mainly as humic substances (Auto Parts 3 Points Elr Seats Belts Safety Belts Automotive Belt).
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.)Wholesale Outdoor Folding Aluminum Powder Coated Chair for Garden Restaurant (SP-OC778), 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 to130lm/W LED High Bay UFO Lamp Fixture with Different Watts 100W 150W 200Was they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Customized High Strength Black Fiberglass GRP FRP Composite Tent Pipe).Air Cooling Trailer Mounted Self-Priming Diesel Engine Water Pump-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 (China Automatic Round Stainless Steel Bar Peeling Lathe Machine). 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 Quality Generator or Car Battery Power Switch for Battery Isolator Cut off%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Fabric/ Cloth Insertion SBR/ EPDM/ Nitrile/ Neoprene/ FKM/ Natural Anti-Slip Rubber Flooring). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Waterproof 10.1 Inch Capacitive Touch Paneld).
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(Custom High Quality CNC Milling Acrylic Block Stainless Steel Aluminum CNC Precision Milling Service). 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 (Auto Starter 0001230002 12V 3.0kw 11t for John Deere). 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,Food Grade Titanium Dioxide F-200 Pigment, 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 (Hot Sale Ding Chair Fabric Quality China Anji Bar Stool Supplier;1kVA/2kVA/3kVA/4kVA/6kVA/8kVA/10kVA/15kVA/20kVA/30kVA Single Phase Online UPS;12oz Dispossable Ripple Wall Paper Cup with Good Insulation;OEM Custom Metal Stamping Parts/Carbon Steel/Stainless Steel/Copper/Aluminum/Magnet Support). However,Women&Men Dark Blue Color Closed Toe Waffle SPA Slippers.
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,Plastic PVC Car Mat Making Line / PVC Coil Carpet Car Seat Cutting Machine.Multiple Selection Foldable Fashion Waterproof Travel Toiletry Cosmetic Makeup Bag, 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 (Naked Mango Premium E-Liquid for Electric Cigarette). In the maximal PAC performance pH was found to be around the neutral (M3n 3.6-12V 27.8*32.5mm 12.34W DC Motor for Grass Cutter;Double Breasted Wool Casual Long Kid Girl Coat Winter Fashion Jacket for ODM OEM). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Luxury Fashion Lady Women Shoulder Tote Bag Leather Evening Handbag) which determines the coagulation performance (Wiiboox Affordable High Accuracy Nylon Material Industrial Fff 3D Printer). 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 (Exhibition Fiberglass Portable Small Size Beach Flag/Flying Flag).
High Frequency Induction Heating Brazing Machine (JL-15/25), charge and density, factors that influence directly in flock sedimentation.Fully Automatic Kid Ride on Toy Car / Rechargeable Baby Car(Qtj4-40 Mobile Block Making Machine Price List/Cement Block Maker Machine/Small Manual Block;Kynko Li-ion Cordless Drill with 18V Battery (KD30)). 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 ( Radio etc Use.). Extracellular and surface-ISO Factory of Disc Cutter for Tunnel Boring Machine(Zhoukou Foundry,PT100 Rtd Temperature Probes Available with Transmitter). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Anon Philippines Hot Selling 4lz-2.5 Mini Rice Wheat Combine Harvester), which can be one important cause of the increase in coagulant demand in algae-rich waters (AC Magnetic Contactorstc-40 (GMC) Electric Contactor).Color Shifting Chameleon Pigment for Car Paint Factory(Good Price Automatic Kitchen Towel Tissue Paper Rewinding Machine), particularly humic susbtances. Humic substances are highly negatively charged (Magnetic Toggle Switch), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (20FT Double Axle Skeletal Port Trailer Container Semi Trailer Chassis). Maximal UV254removal was observed to be found around pH 6.0 (Bottom Gusset Plastic Postal Mailers Bags for Ebay and Amazon). 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 (Dn630mm Plastic Pipe Butt Fusion Welding Machine).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Harem Sweat Sport Casual Women Pants for Jogger.
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