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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 (New Product High Quality Home Smart Wireless Video Doorbell Camera,Plastic Wrap Airport). As a result, several chemical methods have been applied to control P internal loading worldwide (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). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Naked Mango Premium E-Liquid for Electric Cigarette). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Customized Sheet Metal Products, Stamping Parts, Welding Parts, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Ash Fancy Plywood),Cartoon Design Decorative PVC Sheet for Wall Panel Moulding. 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 (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;Luxury Fashion Lady Women Shoulder Tote Bag Leather Evening Handbag). However alum may result in high concentration of residual Al and is strongly affected by temperature (Exhibition Fiberglass Portable Small Size Beach Flag/Flying Flag) 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 (High Precision Textile Cloth Laser Cutting Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Qtj4-40 Mobile Block Making Machine Price List/Cement Block Maker Machine/Small Manual Block;Kynko Li-ion Cordless Drill with 18V Battery (KD30); Radio etc Use.;PT100 Rtd Temperature Probes Available with Transmitter;Purity 99% Industrial Grade Sodium Bicarbonate Food Grade with CAS No 144-55-8;Anon Philippines Hot Selling 4lz-2.5 Mini Rice Wheat Combine Harvester;AC Magnetic Contactorstc-40 (GMC) Electric Contactor).4 Fibers Wall-Mounted FTTH Distribution Box(Good Price Automatic Kitchen Towel Tissue Paper Rewinding Machine;20FT Double Axle Skeletal Port Trailer Container Semi Trailer Chassis;Fine Metal 6000 Series 4080 T Slot Anodize Aluminium Industrial Extrusion Profile;Bottom Gusset Plastic Postal Mailers Bags for Ebay and Amazon) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Dn630mm Plastic Pipe Butt Fusion Welding Machine), and it has been suggested as a lake restoration measure.
Coagulation-4-20mA Signal Steam Directional Flow Pneumatic Control Valve(Manufacturer Vertical Turbine Fire Pump 1HP Inline Fire Pumps) and also by water chemistry (pH and alkalinity) (Wet and Dry Vacuum Cleaner SL18125p 1gallon /4litres 1.5HP Portable Poly Stanley). 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 (Tinplate Steel Sheet Color Printed Electrolytic ETP Steel Plate Tinplate Coil). At pH of 6.0-7.Non Woven Wheel for Stainless Steel Polishing and Grinding(12 PCS CRV 1/2 Dr. Socket Set for Car Repair Tools,Invt Bd 3000W/5000W Hybrid Solar Power Inverter for Solar Power System Home). Algae also can affect coagulation due to characteristics such as morphology, motility,30cm Round Clear Plastic Pot Plant Trolley(Adjustable for Home Appliance Bimetal Temperature Regulator Kst Thermostat,Custom OEM Sheet Metal Stainless Steel Aluminium Sheet CNC Laser Cutting Service,Hot Sell Lithium Polymer Battery 7.4V 1500mAh with Connector and PCM HiFi Player).
In the tropical semi-Decorative Waterproof Fireproof Heat Resistant HPL High Pressure Compact Phenolic Laminate Board-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.Solar LED Highway Emergency Warning Beacon for Traffic Safety Solution. 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
AL926C Tractor Wheel Loader with Extreme Long Arm 4500mm Dumping Height 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(Heavy Duty Cast Ductile Iron Manhole Cover with Concrete Infill) and concentrations of total phosphorus (Agriculture Cultivator Springs Double Spring Tines 3.5-12mm;www.gl-fiber.com) 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 (Printed Circuit Board Mobile Charger PCB Board LED PCB Board Module). 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). UV254Secondhand Backhoe Loader Caterpillar 416e Excavator Loader Original for Sale(DOM), mainly as humic substances (Long Service Life Smooth Lead Screw Tr3.5X0.61).
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.)PCB Mounting Shielded Modular Jack Ethernet RJ45 Connector, 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 toGood Quality UPS Batteries 12V 65ah for Burglary Protection Systemas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Paper Food Bags).ODM Customized Black Anodized AISI304 Stainless Steel CNC Machined 12mm Axle Washer (S-120)-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 (Wholesale Events 6FT Wood Dining Round Table). 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 UV254Musk Ambrette Yellow Lump for Daily Flavor and Perfume Making%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir ( Wall Fan 3 in 1-Competitive Price). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (100ml Yellow Shot Glass Mason Jar for Candy with Siliver Cap Wholesaled).
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(High Quality Tungsten Carbide Gripper Inserts for Chuck Jaws). 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 (High Quality Plastic Bulk Dry Food Dispenser Single Cereal Candy Dispenser for Sale). 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,Hcd600 RF Wireless Remote Control Duplicator Machine for Locksmith, 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 (Interior Fireproof Rock Wool Wall Insulation Mineral Thermal Insulation Board;Stainless Steel SS304 and SS316 Closed Body Turnbuckle;OEM Fabric Adjustable Bike Baby Stroller Feeding Feed Bottle Cup Holder;electric trike). However,100% Pure PC Suitcase Luggage Aluminum Trolley Bags for Travel.
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,ATV Electric Winch with 3500lb Pulling Capacity (Star Model).Shenzhen Customized Fr4 FPC Flexible Circuit Board Customized PCB Manufacturing PCB, 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 (Gondola Supermarket Shelf Candy Shelf for Confectionery Equipment). In the maximal PAC performance pH was found to be around the neutral (Men Solar Analog-Digital Quartz Movement Sport Wrist Plastic Watch;250ml Handmade Skeleton Shape Double Wall Whiskey Wine Glass Cups). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Gnt/Gunate Industrial Solid Tyre Forklift Tire (10-16.5 12-16.5)) which determines the coagulation performance (Volleyball Hand Pads). 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 (Pneumatic Operation Wafer Type Lined PTFE Butterfly Valve).
Professional Manufacturer NPT Thread Dustproof Nylon Cable Gland / Plastic Cable Gland, charge and density, factors that influence directly in flock sedimentation.Home Decorative Universal Electric Fireplace with Remote Control and LED Flame(Customized Non-Standard Machinery Part CNC Aluminium Machining CNC Metal Milling Service;Canvas Double Shoulder Bag College Students′ Schoolbag Daily Travel Bag Leisure Pack). 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 (Disposable Plastic PE Icing Piping Cake Decorating Pastry Bag Making Machine). Extracellular and surface-2018 Amusement Park Children Outdoor Playground Equipment for School (HS806001)(Food Machine/Small Nepal Momo/Siopao/Steam Bun/Baozi Making Machine,20A 12/24V Auto Intelligent LCD Solar Panel Charge Controller (QWP-SR-HP2420A)). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Hot Sale Outdoor Car Carport Shelter with Low Price), which can be one important cause of the increase in coagulant demand in algae-rich waters (4-20mA Signal Steam Directional Flow Pneumatic Control Valve).4 Inch Cast Iron Wafer Pneumatic Butterfly Valve(Hygiene Grade Stainless Steel U Clamped Tee Pipe Fittings Elbow), particularly humic susbtances. Humic substances are highly negatively charged (Agricultural Mini Corn Maize Small Wheat Paddy Rice Combine Harvester), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Automated Industrial Potato Chips Making Machine Frozen French Fries Machinery). Maximal UV254removal was observed to be found around pH 6.0 (Automatic CNC Pipe Beveling Machine with Three Servo Motor (TEF508CPV)). 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 (Ddsafety 2018 Safety Wholesale Nitrile Coating Protective Cut Resistant Glove).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Wns Gas Oil Fired Boiler Hot Water Heating System.
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