Introduction to Issues and Technology in Water Contaminants

About 70% of the earth’s surface is covered with water. Although the quantity of water on earth is vast, most of this does not fit for direct human consumption, particularly the saline water. The most accessible source of fresh water for human consumption is the surface water, including rivers and lakes, which consist of about 0.3% of the total fresh water volume on earth (Gleick, 1996). Unfortunately, the access to clean fresh water is inadequate in many parts of the world. This is largely due to the deterioration of raw water quality and the threat of water contaminants

Phosphorus and eutrophication in water

Since early 1970, the presence of phosphorus (P) in domestic wastewater has attracted attention due to the awareness of its adverse impacts on the environment, specifically in receiving water such as a river. In the wastewater treatment system, P is a crucial nutrient for bacteria required to degrade and biologically stabilise the organic wastes (Hussain et al., 2001). P is a key nutrient that stimulates the growth of algae and other biological organisms (Mainstone and Parr, 2002). P appears exclusively as orthophosphate, condensed phosphates (polyphosphates), and organically bound phosphate. Condensed phosphates are utilised in cleaning products, and organic phosphates are elements of the body and food waste (Howard, 1985). According to Tjandraatmadja et al. (2010), household products can be a significant contributor to the P load in domestic wastewater. The release of high quantities of P from domestic wastewater treatment plants is of concern, as it is one of the key nutrients that have the potential to contribute to eutrophication in surface water, which can result in excessive growth of algae (Daniel et al., 1994)

Utilization of durian peel as potential adsorbent for bisphenol a removal in aquoeus solution

This study explored the low-cost adsorbent of durian peel for BPA removal from aqueous solutions. The effect of various operational parameters such as contact time, temperature, concentration, agitation and pH on the adsorption of BPA was investigated using the batch adsorption study. It was found that Durian peel can be used as a low cost adsorbent for the removal of BPA in aqueous solution after treated with sulfuric acid. The effects of morphology, functional groups, and surface area of adsorbent, before and after pretreatment with sulfuric acid and reaction were investigated by using FESEM, FTIR, and BET. The present study indicates that durian peel had removed 69.63% of BPA with adsorption capacity of 4.178 mg/g for 24 hours. The result proved that this treated agricultural waste was promising material as an alternative adsorbent for the removal of BPA from aqueous solution. Kinetic study of the results gave a pseudo-second order type of mechanism while the adsorption characteristics of the adsorbent followed the Langmuir adsorption isotherm

Fabrication and characterisation of superhydrophobic bio-ceramic hollow fibre membranes prepared from cow bone waste

Superhydrophobic membranes have great potential towards various application, especially for thermal-based membrane system such as membrane distillation. In this study, bioceramic hollow fibre membranes derived from cow bone waste were prepared by phase inversion/sintering method, followed by surface modification via immersion grafting with fluoroalkylsilane (FAS) agent. Interestingly, the grafting process led to the formation of hydroxyapatite nanorods, mimicking the unique structure of electrospun nanofiber membranes. The hydrophobicity of the modified membranes was assessed by measuring the water contact angle and showed excellent improvement from hydrophilic property to superhydrophobic with the highest value of 174° After the modification, the water entry pressure also improved from 0 to 1 bar. In addition, the presence of FAS agent on the membrane surface was observed using X-ray photoelectron spectroscopy (XPS). A correlation between pore size, porosity, and mechanical strength of the modified membrane was discussed; the increment of membrane pore size after grafting process is synonym to the dental erosion mechanism. The result indicates that the superhydrophobic bioceramic hollow fibre membranes derived from cow bone waste have significant potential to be developed for membrane distillation application in treating water and wastewater

High flux polysulfone braided hollow fiber membrane for wastewater treatment role of zinc oxide as hydrophilic enhancer

Incorporation of zinc oxide (ZnO) nanoparticles has played an important role on the improvement of unique membrane characterization and performance, most notably the hydrophilic modification of the membrane for higher pure water permeability. Additionally, the permeability of the membrane can be improved via introduction of braid support by reducing the thickness of the membrane separation layer. Moreover, the braided hollow fiber membrane (BHFM) is able to perform under higher pressure conditions compared to hollow fiber membranes. In this paper, hybrid polysulfone (PSf)/ZnO BHFMs were fabricated via phase inversion method. Hydrophilic 10 ± 1.8 nm polycrystalline ZnO nanoparticles synthesized via sol-gel method were incorporated on BHFM to improve the hydrophilicity and increase flux with constant rejection under high pressure and the effect of the ZnO loading on the membrane properties and performance were thoroughly studied. The fabricated BHFMs with 0.0, 0.5, 1.0 and 1.5 wt% of ZnO nanoparticles concentration were defined as BHFM1, BHFM2, BHFM3 and BHFM4 respectively. Scanning electron microscopy (SEM), contact angle, mechanical strength, flux performance, rejection with bovine serum albumin (BSA) and fouling of best performed membrane were conducted to achieve the target of this paper. The performance of these hybrid ZnO/PSf BHFMs were compared with neat PSf hollow fiber membrane (HFM) and previous studies. The findings from this research work shows that BHFM4 has the most desired properties for wastewater treatment application. The ZnO nanoparticles in BHFM4 have improved hydrophilicity from 108.79° to 71.02°, and thus BHFM4 has increased flux performance from 36.20 to 919.12 L/m2 h at 1.0 bar pressure and 193.48 to 1909.11 L/m2h at 4.0 bar pressure when compared with BHFM1. Constant BSA rejection rates (> 90%) were observed in all BHFMs. The improved hydrophilicity and pure flux performance with constant rejection rate in high pressure conditions illustrates the suitability of fabricated ZnO/PSf BHFMs in wastewater treatment applications

Novel ceramic hollow fibre membranes contactor derived from kaolin and zirconia for ammonia removal and recovery from synthetic ammonia

The adverse effects of ammonia found in wastewater streams lead to the development of advanced water treatment technology, i.e. membrane contactor (MC). In this study, single layer hollow fibre membrane (SLZK) and dual layer hollow fibre membrane (DLZK) were prepared from zirconia and kaolin and modified into hydrophobic membrane through simple grafting process via fluoroalkylsilane (FAS) agent. The properties of membranes such as morphology, surface roughness, mechanical strength, wettability and liquid entry pressure were analysed through scanning electron microscopy (SEM), atomic force microscopy (AFM), 3-point bending strength, contact angle and LEPw setup. Finally, the performance of the membranes was also investigated towards ammonia removal via membrane contactor system. Our findings showed that hydrophobicity properties significantly improved for both SLZK and DLZK membranes after grafting modification process as indicated by the increase of contact angle value from 5° and 1° to 132.7° and ~180.0° respectively. Based on the morphological analysis, the surface of DLZK showed more porous structure as compared to the SLZK. In addition, DLZK also displayed the highest mechanical strength and contact angle reading of 125 MPa and ~180° respectively. This suggests that the DLZK showed an excellent membrane contactor performance with highest value of mass transfer coefficient (3.77 x 10-5 ms-1) and almost complete removal of ammonia removal (91%). Overall, these results implied that dual layer ceramic membrane developed from kaolin and zirconia could provide the basis for the development of alternative ceramic membrane with excellent properties for membrane contactor system

Fabrication of high performance PVDF hollow fiber membrane using less toxic solvent at different additive loading and air gap

Existing toxic solvents in the manufacturing of polymeric membranes have been raising concerns due to the risks of exposure to health and the environment. Furthermore, the lower tensile strength of the membrane renders these membranes unable to endure greater pressure during water treatment. To sustain a healthier ecosystem, fabrication of polyvinylidene fluoride (PVDF) hollow fiber membrane using a less toxic solvent, triethyl phosphate (TEP), with a lower molecular weight polyethylene glycol (PEG 400) (0–3 wt.%) additive were experimentally demonstrated via a phase inversion-based spinning technique at various air gap (10, 20 and 30 cm). Membrane with 2 wt.% of PEG 400 exhibited the desired ultrafiltration asymmetric morphology, while 3 wt.% PEG 400 resulting microfiltration. The surface roughness, porosity, and water flux performance increased as the loading of PEG 400 increased. The mechanical properties and contact angle of the fabricated membrane were influenced by the air gap where 20 cm indicate 2.91 MPa and 84.72◦, respectively, leading to a stronger tensile and hydrophilicity surface. Lower toxicity TEP as a solvent helped in increasing the tensile properties of the membrane as well as producing an eco-friendly membrane towards creating a sustainable environment. The comprehensive investigation in this study may present a novel composition for the robust structure of polymeric hollow fiber membrane that is suitable in membrane technology

Chapter 10 - Sustainable engineering of food waste into high-quality animal feed using a drying technology

Sustainable management through recycling of the food waste into animal feedstock is one of the promising approaches to overcome the food wastage-related issues. However, this action has been limited in some developed countries due to the lack of safety and security issues. Food waste contains high moisture content and it causes the spread-out of bacteria such as Escherichia coli, Salmonella, and sulfate reducing bacteria. The presence of these pathogens might cause food waste to be contaminated and causes infectious and pandemic diseases to human beings via animals. Thus this chapter aimed to discuss a case study where the evaluation of an effective method for food waste recycling is highlighted. As the food waste pre-drying facilities for the prerequisite animal feedstock pellets testimonial, this study ensures the end products processed inside the university (Universiti Teknologi Malaysia) are safe to be used as animal feeds by investigating the quality of end products. The observation reveals that solar drying food waste exhibits high protein and low moisture contents which the percentage is reached to 22% and 20%, respectively. Meanwhile, the oven drying method could reduce the E. coli content to only 500×103 CFU/g. Therefore, the solar drying method is the most effective to reduce high moisture content and able to achieve high protein content which is acceptable to be used as animal feeds

Interpretation of isotherm models for adsorption of ammonium onto granular activated carbon

High amounts of ammonium (NH4+) discharged in receiving water can lead to eutrophication. The adsorption of NH4+ from synthetic solution onto granular activated carbon (GAC) was scrutinized with respect to initial solute concentration (10 mg L-1 ), solution volume (0.2 L), adsorbent dosage (4 – 20 g), and contact time. Experimental data can be well described by the pseudo-second-order kinetic model (R2 > 0.994) and Freundlich isotherm model (R2 = 0.936), suggesting that chemisorption and multilayer adsorption occurred. Furthermore, this study explored the feasibility of using the Freundlich isotherm model to estimate the removal efficiency or required amount of adsorbent. The result findings indicated that GAC has a good potential to adsorb NH4+ from water and thus giving new insights into environmental engineering practices