Key issues to consider when using alum sludge as substrate in constructed wetland

2015 ◽  
Vol 71 (12) ◽  
pp. 1775-1782 ◽  
Author(s):  
Xiaohong Zhao ◽  
Yaqian Zhao ◽  
Wenke Wang ◽  
Yongzhe Yang ◽  
Akintunde Babatunde ◽  
...  
Keyword(s):  
Constructed Wetland ◽  
Low Cost ◽  
High Strength ◽  
Dry Weight ◽  
Treatment Efficiency ◽  
Aluminium Sulphate ◽  
Key Issues ◽  
Alum Sludge ◽  
Biofilm Development

Globally, alum sludge is an easily, locally and largely available by-product from water treatment plants where aluminium sulphate is used as the coagulant for raw water purification. Owing to the high content of Al ions (29.7 ± 13.3% dry weight) in alum sludge and the strong affinity of Al ions to adsorb various pollutants especially phosphorus (P), alum sludge (in the form of dewatered cakes) has been investigated in recent years as a low-cost alternative substrate in constructed wetland (CW) systems to enhance the treatment efficiency especially for high strength P-containing wastewater. Long-term trials in different scales have demonstrated that the alum sludge-based CW is a promising technique with a two-pronged feature of using ‘waste’ for wastewater treatment. Alum sludge cakes in CW can serve as a medium for wetland plant growth, as a carrier for biofilm development and as a porous material for wastewater infiltration. After the intensive studies of the alum sludge-based CW system, this paper aims to address the key issues and concerns pertaining to this kind of CW system. These include: (1) Is alum sludge suitable for reuse in CWs? (2) Is Al released from the sludge a concern? (3) What is the lifespan of the alum sludge in CWs? (4) How can P be recovered from the used alum sludge? (5) Does clogging happen in alum sludge-based CW systems and what is the solution?

A Review on the Use of Engineered Cementitious Composite in Bridges

2016 ◽  
Vol 860 ◽  
pp. 125-134 ◽  
Author(s):  
Abla Krouma ◽  
Zubair Imam Syed
Keyword(s):  
Low Cost ◽  
Steel Corrosion ◽  
High Strength ◽  
Highway Bridges ◽  
Self Healing ◽  
Cementitious Composite ◽  
Long Term Effects ◽  
Engineered Cementitious Composite ◽  
Water Permeability Coefficient

Engineered Cementitious Composite (ECC) is a material with high ductility, tensile strength and self-healing more than the standard concrete. Applications of ECC are beneficial due to its long life cycle, high strength, low cost in the long-term, low maintenance and environmentally friendly nature. Properties and hardened behavior of ECC highlights that ECC has a tight crack width development, which increases its ability to resist long-term effects of hot, frost and humid weather. Additionally, it results low water permeability coefficient and high steel corrosion resistance compared to other common alternative materials. One of the promising areas of application for ECC is in highway structures, especially highway bridges. Highway structures suffer constantly from adverse environmental loads and often require frequent repairing or replacing due to cracks; expansion; water and chlorides effects which cause steel corrosion or the slope between the pavement, slab and the support at the end of a bridge. Detailed review on different properties and characteristics of ECC and the current applications of ECC clearly highlights the motivation to enhance the use of ECC for bridge construction. In addition, ECC can be introduced in jointless bridges by putting an ECC link slab instead of the expandable mechanical joint.

SOME KEY ISSUES AND ACCESSES TO THE APPLICATION OF MAGNESIUM ALLOYS

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2237-2242 ◽  
Author(s):  
YUAN HAO ◽  
TIJUN CHEN ◽  
YING MA ◽  
YUANDONG LI ◽  
FENGYUN YAN ◽  
...  
Keyword(s):  
High Performance ◽  
Low Cost ◽  
High Strength ◽  
Az91d Alloy ◽  
Effective Surface ◽  
Forming Technology ◽  
The Status ◽  
Micro Arc Oxidation ◽  
Key Issues ◽  
Mould Casting

The status of Mg alloy application, and then some key issues limiting their applications and the corresponding accesses were briefly discussed. It was supposed that development of new alloys with high performance and low cost, investigating advanced forming technology, and development of credible and effective surface modification technologies and related equipment were the urgent tasks in present. Correspondingly, three aspects of researches were carried out. (1) A new alloy with high strength and elongation, but low RE and Zn contents, named ZW21, was invented. (2) Semisolid ingots of AZ91D, AM60 and ZW21 alloys available for thixoforming were prepared. Thixoforming increased the ultimate tensile strength of AZ91D alloy by 20% compared with permanent mould casting. (3) A new kind of micro arc oxidation equipment with a capacity of treating 6m2 surface was developed and has been used to treating motorcycle hub of magnesium alloy.

Total and hexavalent chromium removal in a subsurface horizontal flow (h-SSF) constructed wetland operating as post-treatment of textile wastewater for water reuse

2011 ◽  
Vol 64 (4) ◽  
pp. 826-831 ◽  
Author(s):  
D. Fibbi ◽  
S. Doumett ◽  
I. Colzi ◽  
E. Coppini ◽  
S. Pucci ◽  
...  
Keyword(s):  
Hexavalent Chromium ◽  
Constructed Wetland ◽  
Water Reuse ◽  
Textile Wastewater ◽  
Trivalent Chromium ◽  
Post Treatment ◽  
Chromium Removal ◽  
Treatment Efficiency ◽  
Reed Bed

In this study we investigated total and hexavalent chromium removal in an h-SSF constructed wetland (CW) planted with Phragmites australis and operating as post-treatment of effluent wastewater from an activated sludge plant serving the textile industrial district of Prato (Italy). Two measurement campaigns were carried out in 2006 and 2008–2010 in which more than 950 inlet and outlet samples were analyzed. When inlet and outlet concentrations were compared one to the other, the latter were found to be significantly lower than the former (p < 0.001); during the entire period of investigation, removal of hexavalent chromium equal to about 70% was achieved. Outlet concentrations ranged between values lower than the quantification limit (0.5 μg L−1) and 4.5 μg L−1, and in all cases were therefore lower than the limit indicated for hexavalent chromium in the Italian regulation for water reuse (5 μg L−1). The comparison of the removal efficiencies achieved for hexavalent and trivalent chromium during the two campaigns suggested that the removal of the former can be sustained in the long term, while for the latter, the treatment efficiency is more sensitive to the age of the CW, being that it is it based on trivalent chromium retention in the reed bed.

scholarly journals Variation of Water Treatment Efficiency during Long-term Operation of Constructed Wetland

2011 ◽  
Vol 53 (6) ◽  
pp. 121-128
Author(s):  
Yeong-Kwon Son ◽  
Chun-Gyeong Yoon ◽  
Hyung-Joong Kim ◽  
Jong-Hwa Haam
Keyword(s):  
Water Treatment ◽  
Constructed Wetland ◽  
Treatment Efficiency ◽  
Term Operation

Decomposition of the metastable beta titanium alloy Ti-15-3

1983 ◽  
Vol 41 ◽  
pp. 264-265
Author(s):  
Y. L. Chen ◽  
S. Fujlshiro
Keyword(s):  
Low Cost ◽  
High Strength ◽  
Alpha Phase ◽  
Thick Sheet ◽  
Omega Phase ◽  
Beta Titanium Alloy ◽  
Beta Titanium ◽  
Beta Matrix ◽  
Metastable Beta ◽  
Very High

Metastable beta titanium alloys have been known to have numerous advantages such as cold formability, high strength, good fracture resistance, deep hardenability, and cost effectiveness. Very high strength is obtainable by precipitation of the hexagonal alpha phase in a bcc beta matrix in these alloys. Precipitation hardening in the metastable beta alloys may also result from the formation of transition phases such as omega phase. Ti-15-3 (Ti-15V- 3Cr-3Al-3Sn) has been developed recently by TIMET and USAF for low cost sheet metal applications. The purpose of the present study was to examine the aging characteristics in this alloy.The composition of the as-received material is: 14.7 V, 3.14 Cr, 3.05 Al, 2.26 Sn, and 0.145 Fe. The beta transus temperature as determined by optical metallographic method was about 770°C. Specimen coupons were prepared from a mill-annealed 1.2 mm thick sheet, and solution treated at 827°C for 2 hr in argon, then water quenched. Aging was also done in argon at temperatures ranging from 316 to 616°C for various times.

Fine Particle Mass Monitoring with Low-Cost Sensors: Corrections and Long-Term Performance Evaluation

2019 ◽  
Author(s):  
Carl Malings ◽  
Rebecca Tanzer ◽  
Aliaksei Hauryliuk ◽  
Provat K. Saha ◽  
Allen L. Robinson ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Fine Particle ◽  
Low Cost ◽  
Particle Mass ◽  
Long Term Performance ◽  
Term Performance

Subcritical Crack Growth and Long-Term Strength in Rock and High-Strength and Ultra Low-Permeability Concrete

2009 ◽  
Vol 58 (6) ◽  
pp. 525-532 ◽  
Author(s):  
Yoshitaka NARA ◽  
Masafumi TAKADA ◽  
Daisuke MORI ◽  
Hitoshi OWADA ◽  
Tetsuro YONEDA ◽  
...  
Keyword(s):  
Crack Growth ◽  
Subcritical Crack Growth ◽  
High Strength ◽  
Low Permeability ◽  
Term Strength

INCONEL ALLOY X-750

Alloy Digest ◽  
1966 ◽  
Vol 15 (7) ◽  
Keyword(s):  
Gas Turbines ◽  
Rupture Strength ◽  
Low Cost ◽  
High Strength ◽  
Heat Treating ◽  
Chromium Alloy ◽  
Cryogenic Temperatures ◽  
Inconel Alloy ◽  
Nickel Chromium ◽  
Corrosion And Oxidation

Abstract INCONEL alloy X-750 is an age-hardenable, nickel-chromium alloy used for its corrosion and oxidation resistance and high creep rupture strength at temperature up to 1500 F. It also has excellent properties at cryogenic temperatures. It was originally developed for use in gas turbines, but because of its low cost, high strength and weldability it has become the standards choice for a wide variety of applications. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep and fatigue. It also includes information on forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-115. Producer or source: Huntington Alloy Products Division, An INCO Company.

KUBOTA KNC-03

Alloy Digest ◽  
2010 ◽  
Vol 59 (1) ◽  
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
High Strength ◽  
Temperature Performance ◽  
Resistance To Oxidation

Abstract Kubota KNC-03 is a grade with a combination of high strength and excellent resistance to oxidation. These properties make this alloy suitable for long-term service at temperature up to 1250 deg C (2282 deg F). This datasheet provides information on physical properties, hardness, elasticity, tensile properties, and compressive strength as well as creep. It also includes information on high temperature performance as well as casting and joining. Filing Code: Ni-676. Producer or source: Kubota Metal Corporation, Fahramet Division. See also Alloy Digest Ni-662, April 2008.

Sign in / Sign up

Export Citation Format

Share Document