Review on biofilm processes for wastewater treatment

This review paper discusses the application of biofilm as an alternative technology for the treatment of wastewater under various loading and operation conditions. In the past few years the biofilm technology has become more common and widely used in the world to meet the requirement for clean water sources of the world’s growing population. Besides, the conventional wastewater treatment plants like activated sludge process present some shortcomings such as not very flexible method (if there is sudden change in the character of sewage and the effluent of bad quality is obtained), so better system is urgently needed to provide additional capacity with the least possible cost and to meet the standard effluent by the local authorities. The increased incoming flow of wastewater to the treatment plants and organic loading always demand for additional treatment capacity. Fundamental research into biofilm is presented in this paper in sections that discuss the use of biofilm whereby a comparison between suspended and fixed film, old and new biofilm are made. Besides, bed types namely moving bed, fixed bed and floating bed, un-submerged fixed film systems of trickling filters and rotating biological contactors are explained. Nutrients removal of nitrogen and phosphorus and nano technology application in biofilm are also explained. Results from investigations of different applications carried out at the laboratory and pilot scales are also discussed

Investigation of activated carbon coating in the adsorption process of methylene blue from aqueous solution

(GAC) on high-density polypropylene (HDPE) in the attempt to use coated HDPE for adsorption applications. Four HDPE substrates were coated by using either sol–gel method, namely TEOS, or Paint- Spray-Dry method, namely applying epoxy resin to HDPE using brushing technique and spraying the AC on the epoxy layer. The ability of these coated surfaces to remove methylene blue (MB) were then investigated. In addition, the durability of the coatings was characterized by using Energy Dispersive X-ray (EDX) and Scanning Electron Microscopy (SEM) on Day 1 and Day 28. Results show that the activated carbon demonstrated a good adsorption capacity his research evaluates various coating methods and conditions of granular activated carbon of 12.75 mg/g at 50 mg/L dye, indicating that regardless of whether the AC is coated or embedded in the epoxy layer, it could be considered as a promising material for the removal of MB dye from aqueous solution. The surface integrity analyses, such as shaking method, were conducted and their results confirmed that granular activated carbon coating has been successfully deposited on the HDPE substrate and that there was no loss of carbon between Day 1 to Day 28

EVALUATION OF NITRIFICATION PROCESS IN CONSTRUCTED WETLANDS: A REVIEW ON NOVEL BIOLOGICAL NITROGEN REMOVAL PROCESSES

Constructed wetlands attracted the attention of researchers as a sustainable, economic, and efficient wastewater treatment technique. Many papers showed the efficient performance of constructed wetlands to treat municipal, industrial, livestock, petroleum, and other types of wastewater, effectively removing organic matters, phosphate, nitrogen, and contaminants of emerging concern such as pharmaceuticals and antibiotics. There have been numerous reviews in the literature that studied nitrogen removal in constructed wetlands from different perspectives. However, the majority are concerned about the conventional nitrification process. It is worth mentioning that some biological nitrogen pathways other than the conventional nitrification process were implemented in constructed wetlands efficiently such as partial nitrification and denitrification, simultaneous nitrification and denitrification, anaerobic ammonium oxidation, and completely autotrophic nitrogen removal over nitrite which have been reviewed in this study. The outcomes of this study showed that anaerobic ammonium oxidation is the most common pathway applied in constructed wetlands. Moreover, this review showed that the efficient performance of these novel pathways is constrained by the difficulty of controlling the operating parameters such as dissolved oxygen, temperature, and pH

Activated carbon-coated cosmo ball biomedia for wastewater treatment

Current wastewater treatment systems, such as oxidation ponds, package systems, aerated lagoon, activated sludge, and various types of mechanical plants require long resident time to treat wastewater pollutants. With increasingly stringent discharge requirement, conventional WWTPs are no longer capable of producing effluent with the required quality. The aim of this study is to improve the surface of attached media in order to obtain a better removal efficiency in a biofilm reactor. Thus, the objectives of the study are to develop coating methods and characterize the coated surface to study the growth rate and mechanism of biofilm formation when a coated surface is used. This study also investigates the performance of activated carbon coated material with respect to organic and ammonia removal. In this research, various coating methods were attempted and the conditions of granular activated carbon (GAC) on high-density polypropylene (HDPE) were evaluated in the effort to enhance the surface area of the HDPE for application in wastewater treatment. In the biofilm study, a batch reactor with four AC coated Cosmo balls and four non-coated Cosmo balls were submerged in a 5-liter container filled with domestic wastewater. A laboratory-scale anoxic-aerobic reactor was installed at the Kolej 10 wastewater treatment plant and performance of the developed lab-scale reactor was evaluated under different conditions for coated and non-coated media. The results of the experiments showed that the granular activated carbon coating with particle diameter from 100 to 800 μm were successfully deposited on the HDPE substrates used. The coatings deposited on the HDPE substrate produced high surface roughness of around 7 μm which is 10 fold higher than non-coated media. The surface area of the coated substrate is higher compared to that of the non-coated substrate due the BET of activated carbon of 426 m2/g. The formation of biofilm was clearly observed after Day 11 to show that the biofilm had covered 100% of coated area as opposed to only an estimated 70% of the non-coated area. The highest removal of TP was achieved with coated Cosmo-Ball reactor which reached over 90% removal without the addition of any chemical, while only 54.6% TP was removed by the non-coated Cosmo-Ball. For organic removal, the coated Cosmo ball achieved 97.6% BOD, 92.2% COD and 98.3% TSS compared to non-coated Cosmo ball which gave 91% BOD, 87.8% COD and 92.47% TSS. Ammonia removal was significantly higher for coated Cosmo ball, 88.1% NH3-N contrast to non-coated 69.2% only. Two kinetic models namely Modified-Stover Kincannon and Grau were also studied to find kinetic parameters and the result showed that Modified-Stover Kincannon model can be recommended to be the best kinetic to use. The result of this research also showed that, after coating, there is four (4)-fold increase in the surface area of the media compared to the non-coated media. This had resulted in a significant decrease of HRT from 6 to 3 hours, and it could also save up to 50% of the volume of aeration tank