Ecophysiology and dynamics of nitrogen removal bacteria in a sequencing batch reactor during wastewater treatment start‑up

Nitrogen removal communities performing wastewater treatment consist of ammonia oxidisers, nitrite oxidisers, denitrifiers, and anammox bacteria, and the proportion and activity of particular microbial groups depend not only on the physiochemical parameters of the bioreactor, but also on the composition of the inoculum. Nitrifiers and denitrifiers usually dominate in conventional wastewater treatment systems due to the fact that nitrification and denitrification are the most commonly used nitrogen removal processes. However, from the economical point of view in case of wastewater with high ammonia concentrations, anammox-based technologies are desirable for their treatment. The disadvantage of such systems is slow anammox bacteria growth, which extends an effective technological start-up. Thus, in this study, a fast start-up of the anammox process supported with an anammox-rich inoculum was performed in a sequencing batch reactor (SBR). Using anammox inoculation of SBR laboratory system, the start-up can be fastened to 85 days with 84.5% of nitrogen removal efficacy. The spatial distribution of nitrogen removal bacteria analysed with fluorescent in situ hybridisation revealed that anammox and nitrifiers are located side by side in the flocs and the relative number of ammonia and nitrite oxidisers decreased after 85 days of the experiment

Rotating biological contactors : a review on main factors affecting performance

Rotating biological contactors (RBCs) constitute a very unique and superior alternative for biodegradable matter and nitrogen removal on account of their feasibility, simplicity of design and operation, short start-up, low land area requirement, low energy consumption, low operating and maintenance cost and treatment efficiency. The present review of RBCs focus on parameters that affect performance like rotational speed, organic and hydraulic loading rates, retention time, biofilm support media, staging, temperature, influent wastewater characteristics, biofilm characteristics, dissolved oxygen levels, effluent and solids recirculation, stepfeeding and medium submergence. Some RBCs scale-up and design considerations, operational problems and comparison with other wastewater treatment systems are also reported.Fundação para a Ciência e a Tecnologia (FCT

Novel Methods and Technologies in Environmental Engineering

The novel technologies used in environmental engineering were discussed in this paper – the formation of aerobic granules, the Anammox process, the advanced oxidation processes, the use of fungi for dyes decolorization, constructed wetlands, the soil phytoremediation supported by rhizosphere microorganisms and the use of molecular biology technique in environmental engineering. The structure of granular sludge is influenced by EPS production. The average diameter and density of biogranules increase due to EPS production. Although polysaccharides are essential, proteins were found to be the predominant component of aerobic granular sludge. Compared to loosely bound EPS (LB-EPS), tightly bound EPS (TB-EPS) showed more significant correlations with granules formation. This investigation will contribute towards a better understanding of the behavior and composition of EPS in sequencing batch reactors. The traditional nitrification and denitrification processes proceed well with typical municipal wastewater. Nevertheless, there are also nitrogen-rich wastewater streams like landfill leachate or reject waters from dewatering of digested sludge, for which traditional nitrification/denitrification can be generally ineffective due to free ammonia inhibition of nitrification and unfavorable biodegradable carbon content for denitrification. Because of high requirements for oxygen and the necessity for addition of external carbon source, treating such nitrogen-rich streams with nitrification/denitrification would become expensive and unsustainable. The least resources consuming pathway for the conversion of ammonium to nitrogen gas is a combination of partial nitrification and the Anammox process. The main advantages of this process compared to the conventional nitrification/denitrification are: low sludge production, decrease of the aeration costs by almost 60% (only half of the ammonia is oxidized to nitrite in the nitritation process without further oxidation to nitrate), and no need for external organic carbon source addition (Anammox process). Furthermore, anammox bacteria oxidize ammonium under anoxic conditions with nitrite as the electron acceptor, and converse energy for CO2 fixation. Additionally, the biomass yield of the Anammox process is very low (0.08 kg VSS kg NH4-N-1 in comparison to 1 kg VSS kg NH4-N-1 in conventional nitrification/denitrification process) consequently, little sludge is produced. The low sludge production is another factor that contributes to the substantially lower operation costs compared to conventional denitrification systems. Advanced oxidation processes (AOPs) are oxidative methods which are based on the generation of the hydroxyl radicals, which are very reactive and less selective than other oxidants. In the wastewater treatment technology, AOPs can be used in a combination with conventional biological techniques (so called hybrid processes), as pre- and post- treatment processes. The advanced oxidation processes have been used in order to increase the biodegradability and also detoxification of the wastewater. The ability of fungi to degrade lignin-cellulose debris is well known. In addition to these natural molecules they may also degrade synthetic compounds, including synthetic dyes. High effectiveness of Evans blue and brilliant green mixture removal by all tested strains was demonstrated. The process was the most effective and fast in shaken conditions. Finally strain MB removed 90% of tested mixture in shaken samples after 96h. It was the best result reached among all the strains used in the experiment. High removal efficiency was accompanied by a decrease of toxicity (from V class to III class in test with D. magna and from IV class even to non-toxic in test with L. minor). The highest decrease of phytotoxicity was noticed in samples with shaken biomass in which the effect of dyes mixture elimination was the best. The research indicates very high potential of tested strains for decolorization and detoxification of dyes mixture. Constructed wetlands are man-made system mimicking the process occurring in natural wetlands. These systems are considered to be an alternative to more technically advanced waste water treatment technologies. The development of constructed wetlands is envisaged to pursue the following directions grouped according to: the type of the waste water to be treated, target contaminants, treatment intensification methods, ancillary benefits and the locality. Mycorrhiza fungi can be used for phytoremediation proccess. They support plant growth by lowering the stress caused by the lack of phosphorus and water. They produce enzymes participating in several stages of xenobiotics decomposition, which is helpful in their further biodegradation performed by the other rhisospherical organisms. The natural colonisation of PAHs contaminated soil is a long-term process. It could be shortend by adding fungal propagules as an inoculum to the soil. Fungi used for the injections should be isolated from PAHs contaminated soil. That guarantees their survival and development in the contaminated environment. The level of PAHs elimination from soil depends on a type of bioremediation modification used. It was shown that the best results are obtained with monocotylous plants combined with bacterial and fungal biopreparations obtained from contaminated soil. The symbiosis of mycorrhiza fungi with monocotylous plants caused ca. 40% increase of 3, 4, 5 and 30% of 6-ring hydrocarbons removal from soil in comparison with the conventional methods. Important aspect of environmental protection and engineering is the possibility for qualitative and quantitative monitoring of complex microbial communities, responsible for biotechnological processes, such as: soil bioremediation, wastewater treatment or composting. Due to the fact that most of the environmental bacteria cannot be grown in the laboratory conditions molecular techniques are widely used in environmental engineering. Among these methods the Polymerase Chain Reaction (PCR)-based and hybridization-based (such as Fluorescent in situ Hybridization; FISH) techniques are known to be the most useful

Application of PCR-DGGE to study genotypic variability of bacteria inhabiting rotating biological contactors treating synthetic coke wastewater

Ze względu na znaczny ładunek azotu amonowego, którym charakteryzują się ścieki koksownicze, dostrzeżono możliwość wykorzystania procesu beztlenowego utleniania amoniaku (Anammox) w procesie biologicznego oczyszczania tych ścieków. W czasie 8-miesięcznego eksperymentu zbadano bioróżnorodność i zmienność mikroorganizmów błony biologicznej w złożu tarczowym oczyszczającym modelowe ścieki koksownicze, ze szczególnym uwzględnieniem grupy bakterii Anammox. Wykorzystując metodę PCR-DGGE wykazano, że w biofilmie złoża tarczowego funkcjonują bakterie z grupy Anammox. Możliwe, że w trakcie trwania eksperymentu nieznany czynnik środowiskowy (prawdopodobnie nagromadzenie azotanów(III)) spowodował znaczne zubożenie biocenozy bakterii Anammox, powodując jednocześnie zmianę jakościową w strukturze całości konsorcjum bakterii. Pomimo zmian jakościowych poziom bioróżnorodności bakterii w trakcie trwania eksperymentu był względnie stały. W oparciu o uzyskane wyniki można przypuszczać, że polimerazy typu TAQ amplifikują cześć materiału DNA ze złoża tarczowego w sposób niespecyficzny, tj. nieulegający rozdziałowi w gradiencie czynnika denaturującego. Zakłada się konieczność wykorzystania innego typu polimerazy (np. proofreading) i/lub zmiany gradientu DGGE w celu rozwiązania tego problemu.High ammonia nitrogen load of coke plant wastewater provided an opportunity to use the Anammox (ANaerobic AMmonium OXidation) process for its biological treatment. Biodiversity and variability of microorganisms in rotating biological contactor (RBC) biofilm treating synthetic coke wastewater was analyzed in the eight-month experiment with the main focus on the Anammox bacteria. Using PCR-DGGE (polymerase chain reaction – denaturing gradient gel electrophoresis) it was shown that the RBC biofilm was populated by Anammox bacteria. Possibly, an unknown environmental factor (probably nitrate(III) build-up) caused significant decrease in Anammox bacteria number, leading to a qualitative change in the total bacterial community structure at the same time. However, despite qualitative changes the bacterial biodiversity level remained relatively constant during the course of the experiment. On the basis of the obtained results it may be assumed that TAQ polymerases amplify part of DNA material from the RBC in a non-specific manner and this material is not separated properly in denaturing gradient. Use of other type of polymerase (e.g. proofreading) and/or change of DGGE gradient is presumed necessary as a solution to this problem

Evaluation with scanning electron microscopy of Cd, Cu, and Zn removal from aqueous solutions by ash from gasification of poultry feathers

Complete nitrogen removal over nitrite (CANON) was used to treat reject water with ammonia concentrations ranging from 70 to 154mg·L-1. Two experimental sequential batch reactors, SBR_A and SBR_B, differed in the time of the reject water inflow (6h40min vs 40min), process temperature (25 vs 29°C), and the number of aeration periods per day (3 vs 6, respectively). Nitrogen removal efficiency was higher in SBR_B (50-90%) than in SBR_A (40-80%). Analysis of total (PCR-DGGE) and active (RT-PCR-DGGE) bacteria revealed that the biodiversity of the bacterial biocenoses, expressed as the Shannon-Wiener Biodiversity Index, was higher in SBR_B (2.75-3.10) than in SBR_A (1.80-2.75)

Influence of the duration of feeding phase on the genotypic structure of bacterial communities in two sequencing batch reactors treating reject water by partial nitritation and anammox

Microbial community and physiochemical processes were monitored by means of denaturing gradient gel electrophoresis (PCR-DGGE) in two sequencing batch reactors (SBRs) running for partial nitritation-anammox and differing in the feeding phase durations (6 h 40 min for SBR1 and 40 min for SBR2). Both SBRs were treated with reject water with a high ammonia concentration (>600 mg for over 370 days. The aim of the experiment was to present the influence of this parameter on total bacterial and anammox bacterial community structure. Molecular analysis revealed that a drastic decrease in influent ammonia concentration to the studied communities caused a change of genotypic structure in their composition. The difference in the reactors working scheme can be the reason for divergence in the community structure though having no drastic influence on its performance and biodiversity level. Feeding time has stronger influence on the genotypic composition of the total bacterial community than on anammox biocenosis

Qualitative analysis of bacterial biocenoses in two sequencing batch reactors treating reject water under different technological conditions

Complete nitrogen removal over nitrite (CANON) was used to treat reject water with ammonia concentrations ranging from 70 to 154mg·L-1. Two experimental sequential batch reactors, SBR_A and SBR_B, differed in the time of the reject water inflow (6h40min vs 40min), process temperature (25 vs 29°C), and the number of aeration periods per day (3 vs 6, respectively). Nitrogen removal efficiency was higher in SBR_B (50-90%) than in SBR_A (40-80%). Analysis of total (PCR-DGGE) and active (RT-PCR-DGGE) bacteria revealed that the biodiversity of the bacterial biocenoses, expressed as the Shannon-Wiener Biodiversity Index, was higher in SBR_B (2.75-3.10) than in SBR_A (1.80-2.75)

Start-up, modelling and simulation of the anammox process in a membrane bioreactor

There are certain well-known methods of diminishing concentrations of nitrogen compounds, but they are ineffective in case of nitrogen-rich wastewater with a low content of biodegradable carbon. Partial nitritation followed by anaerobic ammonium oxidation (Anammox) process appear to be an excellent alternative for traditional nitrification and denitrification. This paper presents the feasibility of successful start-up of Anammox process in a laboratory-scale membrane bioreactor (MBR). It was shown that the combination of membrane technology and Anammox process allowed to create a new highly efficient and compact system for nitrogen removal. It was possible to achieve average nitrogen removal efficiency equal to 76.7 +/-8.3%. It was shown that the start-up period of 6 months was needed to obtain high nitrogen removal efficiency. The applied biochemical model of the Anammox process was based on the state-of-the-art Activated Sludge Model No.1 (ASM 1) which was modified for accounting activity of autotrophs (nitrite-oxidising bacteria and nitrateoxidising bacteria) and anammox bacteria. In order to increase the predictive power of the simulation selected parameters of the model were adjusted during model calibration. Readjustment of the model parameters based on the critically evaluated data of the reactor resulted in a satisfactory match between the model predictions and the actual observations