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A single step process for ammonium removal from nitrogenous industrial effluents with a concomitant generation of algal biomass, which can be used for producing biofuels and other value added products is proposed. A microlagal strain found in the effluent treatment plant of a fertilizer industry in Mumbai, India was systematically adapted to remove up to 700 ppm of ammoniacal nitrogen from industrial wastewater, which is nearly four times higher than the ammonium tolerance reported in the literature as well as other algal strains tested in our laboratory. 18S rRNA sequencing revealed the strain to be Chlorella pyrenoidosa . Effects of process parameters such as pH, temperature and light intensity on cell growth and ammonium removal by the adapted cells were studied. Optimal conditions were found to be pH of 9, temperature of 30 °C and a light intensity of 3500 Lux for the adapted cells.

This paper proposed an enhancement start-up strategy for accelerating the start-up of a membrane bioreactor (MBR) for treating micro-polluted surface water under low temperature. The surface water ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) were firstly enriched in a culture apparatus, and they were further acclimated to surface water through an MBR. Then the prepared mixed liquor obtained from the culture apparatus with natural start-up was introduced into new MBRs fed with reservoir water, and the start-up behaviors were discussed. Results indicated that the enrichment of AOB and NOB lasted for 27 days at 7.3 °C and the acclimation (at 5.9 °C) was completed within 3 days. After inoculating with the prepared mixed liquor, the start-up of the MBR was accomplished within 10 days at 9 °C with the flux of 11 L m–2h–1 (LMH); while operated at lower initial flux (5.5 LMH) and relatively higher temperature (11 °C), it took 3 days for start-up of the MBR. However, the MBRs exhibited stable but not satisfactory organic removals under low temperature during the start-up.

Industrial waste products may be a viable alternative to commercial external carbon sources. In this study, the properties of fusel oil (distillery waste product) were investigated in terms of temperature dependency of denitrification and acclimation period. Furthermore, results obtained during three different full-scale trials were used to verify similarities with and differences from the results obtained under laboratory-scale conditions. Batch experiments with non-acclimated biomass revealed a very strong temperature dependency of the denitrification process (θ = 1.15, R2 = 0.92) in the range of examined process temperatures (13–22 °C). Fusel oil had minor (or no) effects on the behaviour of NO2-N and PO4-P. Significantly lower nitrate utilization rates were observed during acclimation to fusel oil in the full-scale bioreactors compared to a bench-scale reactor. This may primarily be attributed to lower doses of fusel oil, lower process temperatures and more complicated process configurations (resulting in non-optimal use of fusel oil for denitrification). Results obtained from both laboratory-scale experiments and full-scale trials suggested that an acclimation period of a few weeks would be required to reach the maximum denitrification capability of process biomass, even though positive effects of dosing can be observed almost immediately.

Biodegradation of pentachlorophenol (PCP) has been studied in a sequence of two completely mixed reactors. Investigation on the first anaerobic sequencing batch reactor (AnSBR) is discussed in detail in this paper. Key technological and microbiological features were studied: two different types of adaptation process of anaerobic sludge towards PCP detoxication; the influence of the sludge concentration upon the rate of PCP biodegradation; minimum retention time for PCP degradation in dependence on the PCP concentration; modeling of the PCP degradation process; effluent COD and SS concentrations; changes in the micro- and macrostructure of the sludge during acclimatization process.

An investigation was performed to explore the capabilities of a filamentous fungal biomass to grow non-aseptically in a glucose-fed Sequencing Batch Reactor system in very extreme environment (pH 3.5) conditions. Trichoderma viride Pers: Fr. Isolate 8/90 was used as inoculum. Microscopic investigations were carried out to confirm fungal dominance in the open culture. In batch tests, the fungal biomass showed a significant ability to grow and remove the applied organic load (2000 mgGlucose L−1 d−1), with high biomass yields. Furthermore, the biomass showed an ability to resist gallic acid toxicity at high concentraions (1 g L−1) without any pre- exposure acclimation of the biomass. The biomass (about 2.5 gVSS L−1) demonstrated significant aerobic removal of gallic acid in a timeframe of 20 h from initial exposure. The robust characteristics of this SBR system demonstrate potential for future development of fungal based treatment for recalcitrant feedstocks or operation under extreme environmental conditions.

This work presents a comparison of two inocula used for the acclimation of two anaerobic-aerobic sequencing batch bioreactors used for toxic wastewater treatment. The bioreactors were acclimated with different types of sludge: one coming from an anaerobic wastewater treatment plant and the other one from a conventional aerobic activated sludge plant. The model toxic compound was p-nitrophenol, which is reduced to p-aminophenol during the initial anaerobic phase of the reaction, and later mineralized during a posterior aerated reaction phase. Biodegradation of the compounds was monitored using UV/Vis spectrophotometry. After acclimation stabilization of the sludge and of the process was also monitored. Results show that there is no significant difference in acclimation times and stability of the process between the two employed inocula, and thus an originally anaerobic inoculum presents no apparent advantage over a more easily accessible aerobic one.

A two-stage sequencing batch reactor (SBR) system was used for treatment of oily wastewater with COD and oil and grease (O&G) concentrations ranging from 1,722–7,826 mg/L and 5,365–13,350 mg/L, respectively. A suitable start-up protocol was developed using gradual increase in oily wastewater composition with methanol as the co-substrate. This strategy enabled a short acclimation period of 12 days for the sludge in the two-stage SBR to adapt to the oily wastewater. After acclimation, the 1st stage and 2nd stage SBRs were able to achieve COD removals of 47.0 ± 2.4% and 95.3 ± 0.5%, respectively. The 1st stage SBR was able to achieve 99.8 ± 0.1% of O&G removal and effluent O&G from the 1st stage SBR was only 6 ± 2 mg/L. The 2nd stage SBR was used to further remove COD in the effluent from the 1st stage SBR. The final effluent from the 2nd stage SBR had a COD concentration of 97 ± 16 mg/L with no detectable O&G content. Thus, a two-stage SBR system was shown to be feasible for treating high strength oily wastewater to meet the local discharge standards.

The mechanism, technology and character of the anaerobic-aerobic treatment of dye wastewater by combination of fixed film with suspended growth after acclimatization are discussed in this paper. The results show that the COD decreased from 600-900mg/l of influent to about 150mg/l of effluent. The BOD and the dilution times of colourity decreased from 200-300mg/l and 200-500 times to less than 50mg/l and about 80 times respectively, when the HRT and COD RBC-area load of anaerobic and aerobic RBC were 7-8hrs and 4.5-5hrs and 40-50g/m2·d and 30-40g/m2 respectively. This treatment process has the advantage of very low waste sludge. Either anaerobic or aerobic RBC has better quality transmission and mixing ability, so that MLSS in the tank were about 1000-3000mg/l without any blockages of RBC. The efficiency of a 3 stage alone oblique cross passageways packing RBC with sludge return was also high, except in regard to colour under aerobic conditions only.

A pilot-scale anaerobic fixed film reactor (AFFR) with vertically arranged PVC tubes as biomass carrier, treating poultry slaughterhouse wastewater was started-up in 74 days at temperatures between 20-24°C. The start-up process consisted of a long acclimatization phase followed by a low loaded growth phase, a gradual increase of OLR up to 9.2 kg COD/m3d, and a final maturation phase at moderated loads of 2.7 kg COD/m3d at which total COD removal efficiencies of 57% were achieved. Alkalinity ratio IA:PA was found to be the best control parameter to avoid VFA accumulation. OLR increase based on pH control was not satisfactory because changes in CO2 solubility caused daily by temperature and flow variations led to pH oscillations of 0.2 units. The low wastewater alkalinity, 260 mg/l CaCO3, was insufficient to buffer the pH system, therefore the pH decrease associated with the VFA accumulation was not easily detected and could not be used as a way of OLR control. Organic matter removal took place by accumulation and biodegradation processes. Limitation in the reactor hydrodynamics and particulate fraction hydrolysis was detected at high flow rates.

A thermophilic up-flow anaerobic sludge blanket (UASB) reactor was investigated for the decolouration of a synthetic textile wastewater. Textile wastewater is produced at high temperature and dyes are amenable to decolourisation under anaerobic conditions, however this is the first report of the use of such a thermophilic system to aid in the treatment of this wastewater. The decolouration efficiency and robustness of the thermophilic system were compared with a corresponding mesophilic anaerobic system to study the reduction of a selection of reactive dyes, the toxic effect of increasing influent dye concentration (up to 0.64 g.L-1), and the response during acclimation to high salinity conditions (up to 20 g.L-1 as sodium chloride) in three separate stages of experimentation. It was shown that compared with the mesophilic system, the thermophilic UASB treatment gave considerably higher dye decolouration with all the dyes tested, and under all operating conditions investigated. No loss in decolourisation potential was observed during an increase in influent dye concentration. However, toxicity effects were evident, noted by a decrease in COD removal and methane gas production. Acclimation to high salt concentrations also showed an adverse effect upon COD removal and gas production, however dye removal again remained virtually 100 % efficient.

An abundant growth of zoogloeal colonies was observed periodically during some experiments carried out on a bench-scale plant fed with a complex synthetic wastewater. The plant had a configuration with an enhanced regeneration-denitrification-nitrification (R-D-N) activated sludge process for low alkalinity wastewaters. Several operational changes were undertaken in order to suppress the excessive growth of zoogloeal colonies. They included: (1) changes in the wastewater composition, (2) volume changes in the compartmentalization of the anoxic selector, (3) increase of D.O. concentration in the regeneration and nitrification tanks. Conclusions from the plant operation observations give rise to a hypothesis that none of the operational changes provoked a significant restriction in the abundant zoogloeal growth. When a temporary improvement was observed, after acclimatization on the new operational conditions the microorganisms culture returned to its previous state and continued to grow in a wave-mode. The reason for the appearance of this type of sludge might be closely related to the composition of the synthetic wastewater.

A pilot study was conducted to establish feasibility of biological nutrient removal at one of the most advanced wastewater treatments in the U.S. The results of the study revealed technical feasibility of biological phosphorus removal at extremely high F/M (0.84 1/day) and a short hydraulic detention time (2.2 hours) in the first stage activated sludge system. Due to phosphorus limitation of 0.18 mg/l, it was determined that none of the single sludge BNR processes was applicable at this facility. In the second stage, therefore, biological nitrogen removal was achieved with both methanol and primary effluent as a carbon source. Another significant finding was that after acclimation, the primary effluent exhibited the same rate of denitrification as with methanol (2.7 mg NO3− N/gVSS·hr). Further pilot testing revealed correlations among such process variables as detention time, BOD to nitrogen ratio, and effluent nitrogen concentration.

Turbidity and relatively high concentrations of polysaccharides (biopolymers), indicating deflocculation of suspended biomass, could be observed as a result of phenol supplied in transient load conditions. The importance of preliminary acclimation could be observed in terms of the phenol removal rates at relatively low transient loading of phenol, up to 500 mg/l. As shock intensity increased to 1,000 and 1,500 mg/l, the acclimated reactors did not show relevant differences when compared to either partially acclimated or on-acclimated reactors. Transient load conditions created by phenol caused immediate reduction of the oxygen uptake rates and affected biomass respiration. Preliminary acclimation of the biomass indicated possible improvements of these influences, especially for phenol loads of up to 500 mg/l. The period following the application of phenol transient load was characterized by symptoms which could indicate that sorption-desorption mechanisms are involved by biomass, in addition to biodegradation. Preliminary collection and temporary storage of concentrated phenolic wastewater streams followed by gradually controlled release to the treatment facilities would provide reasonable solutions for avoiding biomass deflocculation and process disturbances caused by transient load conditions.

Emission of nitrous oxide (N 2 O) during biological wastewater treatment is of growing concern. This paper reports findings of the effects of carbon/nitrogen (C/N) ratio on N 2 O production rates in a laboratory-scale biological aerated filter (BAF) reactor, focusing on the biofilm during nitrification. Polymerase chain reaction–denaturing gradient gel electrophoresis (PCR-DGGE) and microelectrode technology were utilized to evaluate the mechanisms associated with N 2 O production during wastewater treatment using BAF. Results indicated that the ability of N 2 O emission in biofilm at C/N ratio of 2 was much stronger than at C/N ratios of 5 and 8. PCR-DGGE analysis showed that the microbial community structures differed completely after the acclimatization at tested C/N ratios (i.e., 2, 5, and 8). Measurements of critical parameters including dissolved oxygen, oxidation reduction potential, NH 4 + -N, NO 3 − -N, and NO 2 − -N also demonstrated that the internal micro-environment of the biofilm benefit N 2 O production. DNA analysis showed that Proteobacteria comprised the majority of the bacteria, which might mainly result in N 2 O emission. Based on these results, C/N ratio is one of the parameters that play an important role in the N 2 O emission from the BAF reactors during nitrification.

With the objective of destruction of organic toxic or recalcitrant compounds by a microbial anaerobic mixed population, a new concept has been devised : the Destox concept. It has been applied here to the destruction of a toxic mixture of about 30 polychlorinated aliphatic compounds (PAC-MIX 1), including 51 % of hexachloro-l,3-butadiene. The basic step for initiating the degradation is thought to be reductive dechlorination by microbial interspecies hydrogen transfer in a system using at all times a non-toxic co-substrate as major source of carbon and energy. In an upflow laboratory-scale reactor with a fixed-film stationary-bed, fed with a co-substrate, amounts of 48 mg/litre working volume per day of PAC-MIX 1 have been added during intermittent periods of time. This paper presents, over a period of 421 days, the evolution from a situation of complete inhibition of all microbial activity, from fermentative to methanogenic, into a situation of partial acclimatization, the fermentative and hydrogenotrophic methanogenic bacteria having become resistant to the action of the toxic mixture while acetogenic bacteria seem in the process of acclimatization. The methane production rate was maintained at 30% of the reference value, together with continuous accumulation of mainly acetate and to a lesser extent propionate.