Biodegradation, decolourisation and detoxification of textile wastewater enhanced by advanced oxidation processes

Recently, an increasing application of so called advanced oxidation processes (AOPs) to industrial wastewater has been observed. In particular, an integrated approach of biological and chemical treatment of wastewater is advantageous conceptually. The subject of our study was synthetic wastewater, simulating effluents from knitting industry. The wastewater contained components that are very often used in Polish textile industry: an anionic detergent Awiwaz KG conc., a softening agent Tetrapol CLB and an anthraquinone dyestuff-Acid Blue 40, CI 2125. The toxicity of the detergents and the dye was determined in terms of effective concentration EC50 using mixed cultures of activated sludge as well as pure culture of luminescent bacteria Vibrio fischerii NRRLB-11177. The dye did not undergo biodegradation without AOPs pretreatment, therefore a degree of its removal (decolourisation) by the AOPs has been determined and its bio-sorption properties on the flocks of activated sludge have been studied. The dye adsorption onto flocks of activated sludge was described by Henry's isotherm. Our investigations focussed on the influence of various oxidants like O3, H2O2 and UV light on biodegradation of single components aqueous solution as well as of the whole textile wastewater. The results of kinetic measurements of the biodegradation (by means of acclimated activated sludge) was described by Monod type of kinetic equation. The experimental evidence of the positive effect of chemical oxidation pretreatment on the biodegradation of recalcitrant compounds was quantified by estimation of the kinetic parameters of the Monod equation. Due to the AOPs pretreatment a decrease of the Monod constant and an increase of maximal specific growth rate was observed. The activity of degradative enzymes of activated sludge was assayed by the methods of 2-[4-iodophenyl]-3-[4-nitrophenyl]-5-phenyltetrazolium chloride test.     

Pretreatment of textile dyeing wastewater using an anoxic baffled reactor

A study on pretreatment of textile dyeing wastewater was carried out using an anoxic baffled reactor (ABR) at wastewater temperatures of 5-31.1 degrees C. When hydraulic retention time (HRT) was 8h, the color of outflow of ABR was only 40 times at 5 degrees C and it could satisfy the professional discharge standard (grade-1) of textile and dyeing industry of China (GB4287-92). The total COD removal efficiency of ABR was 34.6%, 47.5%, 50.0%, 53.3%, 54.7% and 58.1% at 5, 9.7, 14.9, 19.7, 23.5 and 31.1 degrees C, respectively. Besides, after the wastewater being pre-treated by ABR when HRT was 6h and 8h, the BOD5/COD value rose from 0.30 of inflow to 0.46 of outflow and from 0.30 of inflow to 0.40 of outflow, respectively. Experimental results indicated that ABR was a very feasible process to decolorize and pre-treat the textile dyeing wastewater at ambient temperature. Moreover, a kinetic simulation of organic matter degradation in ABR at six different wastewater temperatures was carried through. The kinetic analysis showed the organic matter degradation was a first-order reaction. The reaction activation energy was 19.593 kJ mol(-1) and the temperature coefficient at 5-31.1 degrees C was 1.028.     

Enhanced biological treatment of saline wastewater by using halophilic bacteria

Biological treatment of saline wastewater by conventional activated sludge culture usually results in low removal of chemical oxygen demand (COD) because of plasmolysis of the organisms at high salt concentrations. Since salt removal operations by physicochemical processes before biological treatment are costly, a salt-tolerant organism (Halobacter halobium) was used for effective biological treatment of saline wastewater in this study. Halobacter halobium was used in activated sludge culture for COD removal from saline wastewater (1–5% salt) by fed-batch operation of an aeration tank. Inclusion of Halobacter halobium into activated sludge culture improved the rate and extent of COD removals especially with salt above 2% (w/v).     

Behavior of lipids in biological wastewater treatment processes

Lipids (characterized as oils, greases, fats and long-chain fatty acids) are important organic components of wastewater. Their amount, for example, in municipal wastewater is approximately 30–40% of the total chemical oxygen demand. The concern over the behavior of lipids in biological treatment systems has led to many studies, which have evaluated their removal, but still the exact behavior of lipids in these processes is not well understood. In this review, we discuss the current knowledge of how lipids/fatty acids affect both aerobic and anaerobic processes and specific methods that have been used in an attempt to enhance their removal from wastewater. Overall, the literature shows that lipids/fatty acids are readily removed by biological treatment methods, inhibitory to microbial growth as well as the cause of foaming, growth of filamentous bacteria and floc flotation.     

Two-stage biological treatment of olive mill wastewater with whey as co-substrate

Olive mill wastewater (OMW) is a highly polluting wastewater, caused by a high organic load and phenol content. These characteristics suggest that it may be suitable for aerobic treatment and anaerobic bacterial digestion. Aerobic treatment coupled with anaerobic bacterial digestion may be economically feasible as the methane produced is a valuable energy source while simultaneously purifying the OMW. In an attempt to improve the overall performance of the process, the addition of a co-substrate such as whey to the aerobic treatment pre-treatment of OMW by the yeast Candida tropicalis was studied.The two-stage system operated satisfactorily up to an organic loading rate (OLR) of 3.0 kg COD L⁻¹ day⁻¹ with a biogas production rate of 1.25 L_biogas L_reactor⁻¹ day⁻¹ and a total COD reduction in excess of 93% (62% COD reduction in aerobic pretreatment and 83% COD reduction in anaerobic digestion). Fifty-four percent of the phenol was biodegraded during the aerobic treatment stage, and biogas with between 68% and 75% methane was produced during anaerobic digestion.     

Analysis of biological wastewater treatment processes using multicomponent gas phase mass balancing.

A reactor system using off-gas analysis was developed for analyzing wastewater treatment process reactions. Using a mass spectrometer for the gas analysis provides the ability to simultaneously measure several gas components (such as oxygen, nitrogen, carbon dioxide, and argon). One of the benefits of the reactor design was the precise control of the dissolved oxygen concentration, uncoupled from the system turbulence, which was controlled via a gas recycle loop. This feature allowed control of the turbulence within the reactor without any need for mechanical stirring. Using oxygen as the test gas, the reactor was shown to perform well in the measurement of oxygen uptake rate of nitrifying activated sludge. The oxygen uptake rate calculations were made using a simple calibration method developed for the reactor system. The reactor was able to provide precise and accurate results for this test case. Furthermore, the system was capable of measuring under dynamic process conditions, as well as when the process rates were constant (steady state).     

Critical review of the influences of nanoparticles on biological wastewater treatment and sludge digestion

Nanoparticles (NPs), with at least one dimension less than 100?nm, are substantially employed in consumer and industrial products due to their specific physical and chemical properties. The wide uses of engineered NPs inevitably cause their release into the environment, especially wastewater treatment plants. Therefore, it is essential to systematically assess their potential impact on biological wastewater treatment and subsequent sewage sludge digestion. This review aims to provide such support. First, this paper reviews the recent advances on the analytical developments and nano–bio interface of NPs in wastewater and sewage sludge treatment. The effects of NPs on biological wastewater treatment and sewage sludge digestion and related mechanisms are discussed in detail. Finally, the key questions that need to be answered in the future are pointed out, which include on-line revelation of the changes of NPs in sewage and sludge environments, in situ assessment of the variations of microorganisms involved in these biological systems after they are exposed to NPs. Differentiation of the contribution of individual toxicity mechanisms to these systems, and the identification of under what conditions the nanoparticle-induced toxicity will be increased or decreased are also considered.     

Bioaugmentation for enhancing biological wastewater treatment

The literature on bioaugmentation products has been reviewed. Their manufacture and method of use is explained. The various applications are listed and the independent investigations, as opposed to manufacturers accounts, at laboratory and full scale are reviewed. The economics and kinetic modelling are also discussed. In laboratory investigations bioaugmentation often failed, whereas at full scale it was often successful, probably due to the imposition of steady state at laboratory scale. Most products require a period of acclimatisation before working; this and other possible reasons for failure are discussed.     

Floating treatment wetlands as biological buoyant filters for wastewater reclamation

Abstract

Floating treatment wetlands (FTWs) are an innovative product of ecological engineering that can play a promising role in wastewater treatment. It provides low-cost, eco-friendly, and sustainable solutions for the treatment of wastewater, particularly in regions with economic constraints. Generally, FTWs comprise rooted plants that grow on the surface of water with their roots extending down into the pelagic zone rather than being embedded into the sediments. This drooping structure helps develop (1) a hydraulic flow between the root network and the bottom of the treatment system and (2) a large biologically active surface area for the physical entrapment (filtration) of contaminants, as well as their biochemical transformation and degradation. Furthermore, the rooted network allows proliferation of microorganisms that form biofilms and enhance pollutant degradation while promoting plant growth. The augmentation of bacteria in FTWs has been proven to be the most effective approach for reclamation of wastewater. This article discusses the operational parameters of FTWs for maximal remediation of wastewater and highlights the importance of plant-bacteria partnerships in a typical FTW system for enhanced cleanup of wastewater. We propose that this technology is preferable over other methods that require high energy, costs, and area to install or operate machinery.     

污水生物处理中的噬菌体及其功能研究进展

污水生物处理是一种利用微生物分解污水中的污染物、实现污水净化的方法。噬菌体是侵染细菌的病毒,在污水生物处理系统中广泛存在,它们能够特异性地控制微生物菌群,影响污水处理效果和调控污泥性状。因此,研究污水生物处理中噬菌体的分布及其功能具有重要意义。本文介绍了不同污水生物处理中噬菌体的分布,简要分析了噬菌体分离、培养与鉴定方法及其优缺点,详细总结了噬菌体在污水生物处理中的功能,包括:(1)调节微生物群落结构,影响污水处理效果;(2)作为环境监测的指示生物;(3)控制病原菌、污泥膨胀、污泥发泡和膜污染;(4)减少污泥产量,重点分析了影响噬菌体功能的因素,探讨了污水生物处理中噬菌体功能应用存在的问题及其解决方法,最后对噬菌体未来应用的发展方向进行了展望,以期为污水生物处理技术和工艺的开发与应用提供参考,促进污水处理健康发展。     

A kinetic analysis and experimental validation of an integrated system of anaerobic filter and biological aerated filter

An anaerobic/aerobic filter (AF/BAF) system was developed treating dairy wastewater. The influent was blended with recirculated effluent to allow for pre-denitrification in the AF followed by nitrification in the BAF. The recirculation ratio ranged 100-300%. The average chemical oxygen demand (COD) removal efficiency was 79.8-86.8% in the AF and the average total nitrogen removal efficiency was 50.5-80.8% in the AF/BAF system. Steady-state mass balances on the AF were used to analyze removal kinetics in the AF. The kinetic model values for effluent COD in the AF were overestimated as compared with experimental data. The integrated suspended and attached biomass growth rates in the AF were estimated. The specific growth rate of the integrated biomass at each recirculation ratios was 0.6213, 0.6647, and 1.20831/day, respectively. The increase in specific growth rate corresponded to increases in biomass sloughing as the recirculation ratio increased.     

Anaerobic filter treatment of fishery wastewater

Anaerobic treatment of wastewater from a selected seafood processing plant was conducted at organic loading rates (OLR) ranging from 0.3 to 1.8 kg chemical oxygen demand (COD)/m³.day and hydraulic retention times (HRT) ranging from 36 to 6 days. COD reduction decreased with increasing OLR. More than 75% COD reduction could be maintained up to an OLR of about 1 kg COD/m³.day with an HRT of 11 days. An OLR of 1.3 kg COD/m³.day corresponding to an HRT of 6.6 days gave maximal biogas productivity of 1.5 m³/m³.day or 1.3 m³ biogas/kg COD with a 65% COD reduction. If the HRT was kept constant at 11 days, an OLR of 1.3 kg COD/m³.day achieved maximal biogas productivity (1.1 m³/m³.day) and yield (0.75 m³/kg COD) and a 60% COD reduction for treatment of tuna condensate.P. Prasertsan and S. Jung are with the Department of Agro-Industry, Faculty of Natural Resources, Prince of Songkla University, Hatyai 90110, Thailand. K.A. Buckle is with the Department of Food Science and Technology, University of New South Wales, Kensington, NSW 2033, Australia.     

New concept of contaminant removal from swine wastewater by a biological treatment process

Pollution from concentrated animal feeding operations (CAFOs) are the most serious pollution source in China now, and swine wastewater contains high concentrations of nutrients such as chemical oxygen demand (COD), biochemical oxygen demand 5 (BOD5), ammonium, and emergent contaminants related to public health. Biological processes are the most popular treatment methods for COD and ammonium removal. Considering the low operation cost, easy maintenance and high removal rate of contaminants in recent years, nitrogen removal via nitrite and real-time control processes using oxidation-reduction potential (ORP) and/or pH as parameters to control the aerobic and anaerobic cycles of a system has received much attention for animal wastewater treatment. During the biological treatment process, the emergent contaminants such as estrogen, antibiotics, and disinfec-tion reagents have been the focus of research recently, and degradation bacteria and resistance bacteria have also been extracted from activated sludge. The microbial analysis technique is also advancement in the field of biodegrada-tion bacteria and resistance bacteria. All of these advance-ments in research serve to improve wastewater treatment and decrease environmental hazards, especially for using manure as a fertilizer source for crop production.     

微藻废水生物处理技术研究进展

微藻因生长速率快、细胞脂质含量高及具有生物隔离二氧化碳能力,已作为新一代生物质能源受到广泛关注.然而,投入大量淡水资源并需在生长期间持续提供营养物质已成为规模化培育微藻的主要障碍.将微藻培育系统与废水处理相结合是经济可行的污水资源化方案.基于微藻生长期间对氮磷等营养物质的利用机制,本文综述了微藻在各类废水生物处理过程中的应用情况,着重分析了其对废水中有机与无机化合物、重金属以及病原体的去除或抑制能力.同时,考察了废水初始营养物浓度、光照、温度、pH与盐度以及气体交换量等环境因素对微藻生长代谢的影响.此外,结合微藻规模化应用所面临的问题,对微藻废水处理技术的应用前景及发展方向进行了展望,旨在为水生态系统的建设与管理提供参考.     

Anaerobic filter treatment of wastewater from mushroom cultivation on coffee pulp

Wastewater from the pre-treatment of coffee pulp for mushroom cultivation was treated in an anaerobic filter reactor at laboratory scale. The digester was fed semicontinuously with 300 to 500 ml of fresh medium per day. Organic loading rates (OLR) applied ranged widely during the study, from 0.48 to 62.93 g chemical oxygen demand (COD)/1 d. Treating wastewater from the pasteurization of pulp, the highest strength studied, a COD removal efficiency of up to 87% was attained at a high OLR of 42.868 g COD/I d; while a high biogas production rate (BPR) of 2.89 I/I d was also achieved. However, the average organic matter removal efficiency was 53% at an OLR of 23.921 g COD/1 d, which indicates that process efficiency should be improved to achieve a good quality effluent. BPR averaged 1.72 1/1 d, which shows that with technical-scale reactors, high biogas production could be obtained for further use in the pasteurizing process itself (energy recycling).     

The effect of ozone on tannery wastewater biological treatment at demonstrative scale

This paper reports the results obtained during an investigation aimed at transferring to the demonstrative scale an aerobic granular biomass system (SBBGR – Sequencing Batch Biofilter Granular Reactor) integrated with ozonation for the efficient treatment of tannery wastewater. The results show that the integrated process was able to achieve high removal efficiencies for COD, TSS, TKN, surfactants and colour with residual concentrations much lower than the current discharge limits. Furthermore, the process was characterised by a very low sludge production (i.e., 0.1 kg dry sludge/m³ of treated wastewater) with interesting repercussions on treatment costs (about 1 € per m³ of wastewater).     

Recent developments on biological nutrient removal processes for wastewater treatment

The need for preserving the environment is tightening regulations limiting the discharge of contaminants into water bodies. Nowadays most of the effort is done on the removal of more specific contaminants such as nutrients (N and P) and sulfurous compounds since they are becoming of great concern due to its impact on the quality of water bodies. There have been two recent discoveries of microbial conversions of nitrogenous compounds. One consisting on the capability of ammonia oxidizers of denitrify under certain conditions resulting in a new one-step method for the removal of N-compounds. The second has been named the ANAMMOX process, wherein ammonium is oxidized to dinitrogen gas with nitrite as the electron acceptor. Other developments consist of operational strategies aiming at obtaining the highest efficiency at removing nitrogen at lowest cost. One strategy consists of the partial nitrification to nitrite (only successful in the SHARON process) and subsequently either the heterotrophic denitrification of nitrites or its autotrophic reduction by ANAMMOX microorganisms. Another strategy consists of the coexistence of nitrifiers and denitrifiers in the same reactor by implementing high frequency oscillations on the oxygen level.The recent developments on biological phosphorous removal are based on the capacity of some denitrifying microorganisms to store ortho-phosphate intracellular as poly-phosphate in the presence of nitrate. These microorganisms store substrate (PHB) anaerobically which is further oxidized when nitrate is present. By extracting excess sludge from the anoxic phase, phosphate is removed from the system. Removing phosphate using nitrate instead of oxygen has the advantage of saving energy (oxygen input) and using less organic carbon.The microbial conversions of sulfurous compounds involve the metabolism of several different specific groups of bacteria such as sulfate reducing bacteria, sulfur and sulfide oxidizing bacteria, and phototrophic sulfur bacteria. Some of these microorganisms can simultaneously use nitrate, what has been reported as autotrophic denitrification by sulfur and sulfide oxidizing microorganisms. More recently, the anaerobic treatment of an industrial wastewater rich in organic matter, nitrogen and sulfate, reported a singular evolution of N and S compounds that initially was hypothesized as SURAMOX (SUlfate Reduction and AMmonia OXidation). The process could not have been verified nor reproduced and further investigations on the proposed SURAMOX mechanism have given no additional insights to those initial observations.     

Distributed state simulation of endogenous processes in biological wastewater treatment

Distributed state-type simulations (based on modeling of individual bacteria as they move through a reactor system) predicted a greater sensitivity of enhanced biological phosphorus removal (EBPR) performance to endogenous degradation than did conventional, "lumped"-type simulations (based on average biomass compositions). Recent research has indicated that the variable hydraulic residence times experienced by individual microbial storage product accumulating bacteria in systems with completely mixed reactors tend to produce populations with diverse microbial storage product contents (distributed states). Endogenous degradation in EBPR systems is of particular interest because the polyphosphate accumulating organisms (PAOs) responsible for EBPR rely on the accumulation of three different storage products that may be endogenously degraded. Simulations indicated that as endogenous degradation rates of microbial storage products were increased, EBPR performance decreased more rapidly according to the distributed approach than according to the lumped approach. State profile analysis demonstrated that as these rates increased, the population fraction with depleted storage products also increased, and this tended to increase the error in calculated biokinetic rates by the lumped approach. Simulations based on recently reported endogenous rate coefficients also suggested large differences between distributed and lumped predictions of EBPR performance. These results demonstrated that endogenous decay processes may play a more important role in EBPR than predicted by the lumped approach. This suggests a need for further research to determine endogenous process rates, and for incorporation of this information to distributed-type simulators, as this should lead to improved accuracy of EBPR simulations.