Sequencing Batch Biofilter Research Articles

Textile wastewater treatment: Aerobic granular sludge vs activated sludge systems

Textile effluents are characterised by high content of recalcitrant compounds and are often discharged (together with municipal wastewater to increase their treatability) into centralized wastewater treatment plants with a complex treatment scheme. This paper reports the results achieved adopting a granular sludge system (sequencing batch biofilter granular reactor – SBBGR) to treat mixed municipal-textile wastewater. Thanks to high average removals in SBBGR (82.1% chemical oxygen demand, 94.7% total suspended solids, 87.5% total Kjeldahl nitrogen, 77.1% surfactants), the Italian limits for discharge into a water receiver can be complied with the biological stage alone. The comparison with the performance of the centralized plant treating the same wastewater has showed that SBBGR system is able to produce an effluent of comparable quality with a simpler treatment scheme, a much lower hydraulic residence time (11 h against 30 h) and a lower sludge production.

On-site treatment of textile yarn dyeing effluents using an integrated biological–chemical oxidation process

This paper reports the results of the treatment of a yarn dyeing effluent using an integrated biological–chemical oxidation process. In particular, the biological unit was based on a sequencing batch biofilter granular sludge reactor (SBBGR), while the chemical treatment consisted of an ozonation step. Biological treatment alone was first performed as a reference for comparison. While biological treatment did not produce an effluent for direct discharge, the integrated process assured good treatment results, with satisfactory removal of chemical oxygen demand (up to 89.8 %), total nitrogen (up to 88.2 %), surfactants (up to 90.7 %) and colour (up to 99 %), with an ozone dose of 110 mg of ozone per litre of wastewater. Biomass characterization by fluorescence in situ hybridization has revealed that filamentous bacteria represented about 20 % of biomass (coherently with high sludge volume index values); thanks to its special design, SBBGR guaranteed, however, stable treatment performances and low effluent suspended solids concentrations, while conventional activated sludge systems suffer from sludge bulking and even treatment failure in such a condition. Furthermore, biomass characterization has evidenced the presence of a shortcut nitrification–denitrification process.

Study of performances, stability and microbial characterization of a Sequencing Batch Biofilter Granular Reactor working at low recirculation flow

The Sequencing Batch Biofilter Granular Reactor (SBBGR) is a promising wastewater treatment technology characterized by high biomass concentration in the system, good depuration performance and low sludge production. Its main drawback is the high energy consumption required for wastewater recirculation through the reactor bed to ensure both shear stress and oxygen supply. Therefore, the effect of low recirculation flow on the long-term (38months) performance of a laboratory scale SBBGR was studied. Both the microbial components of the granules, and their main metabolic activities were evaluated (heterotrophic oxidation, nitrification, denitrification, fermentation, sulphate reduction and methanogenesis). The results indicate that despite reduced recirculation, the SBBGR system maintained many of its advantageous characteristics.

Is a sequencing batch biofilter granular reactor suitable for textile wastewater treatment?

The textile industry releases highly polluted and complex wastewaters, which are difficult to treat and require numerous treatment steps. Innovative technologies for on-site treatment at each factory would permit cost reduction. For this reason, we ran a laboratory-scale study to assess the suitability of a sequencing batch biofilter granular reactor (SBBGR) for textile wastewater treatment, testing four different types of wastewater. Results demonstrate that wastewater characteristics greatly affect the reactor efficiency. Hence, a pre-study is advisable to define the best operational conditions and the maximum treatment capability for the wastewater under analysis. Nevertheless, SBBGR is a valuable biological treatment, effective in the reduction of pollutant load with stable performances despite the variability in wastewater composition. Tests with ozone integration have demonstrated that it is possible to dose small quantities of ozone to obtain an effluent suitable for direct discharge. However, a dynamic ozone dosage should be used to optimize the process as the correct ozone dose strongly depends on the wastewater composition.

Physical characterisation of the sludge produced in a sequencing batch biofilter granular reactor

Sequencing batch biofilter granular reactor (SBBGR) is a recently developed biological wastewater treatment technology characterised by a very low sludge production, among other numerous advantages. Even if costs for sludge treatment and disposal are mainly dependent on the amount of sludge produced, sludge properties, especially those linked to solid–liquid separation, play a key role as well. In fact, such properties deeply influence the type of treatments sludge has to undergo before disposal and the final achievable solids concentration, strongly affecting treatment and disposal costs. As sludge from SBBGR is a special mixture of biofilm and aerobic granules, no information is available so far on its treatability. This study addresses the characterisation of the sludge produced from SBBGR in terms of some physical properties (settling properties, dewaterability, rheology). The results show that such sludge is characterised by good settling and dewatering properties, adding a new advantage for the full-scale application of SBBGR technology.

Integrated biological and ozone treatment of printing textile wastewater

Textile effluents are among the most difficult industrial wastewaters to treat because of their compositional variability and of the presence of numerous different chemicals intentionally designed to resist degradation. Though biological technologies offer a cheaper and more environmental friendly alternative for the treatment of textile effluents, an additional step to remove recalcitrant compounds is still needed. Integrated biological and chemical treatment is a rather new approach that allows improving treatment performance and stability without increasing too much treatment costs. Ozone integration in a sequencing batch biofilter granular reactor was tested at laboratory scale for treating a printing wastewater characterized by high concentrations of surfactants and nitrogen. The process was optimized in terms of applied organic load and ozone dose. The results have shown that the process assures the possibility to comply with the limits for direct discharge for all investigated parameters by operating at an organic load value lower than 1.5kgCOD/m3d and with an ozone dose of 135mg/l. A synergetic biological and chemical oxidation activity was observed with a ratio between ozone dose and COD removed lower than 0.75. Finally, the process was characterized by a sludge production as low as 0.17kgTSS/kgCODremoved due to the high biomass concentration in the biological system used.

Effective aerobic granular sludge treatment of a real dyeing textile wastewater

This paper reports the results obtained using the sequencing batch biofilter granular reactor (SBBGR) for the treatment of the wastewater from a dyeing and finishing factory. The treatment of such a wastewater is challenging as it usually contains considerable amounts of different recalcitrant, toxic and inhibitory pollutants, which results in low biodegradability and in the need for numerous treatment steps. Different operational conditions were tested in order to assess SBBGR performance as a function of the applied organic and hydraulic load and to verify its suitability for on-site dyeing wastewater treatment at each factory. The reported measurements demonstrate how this innovative biological technology exhibits various promising features for this purpose, as good treatment efficiencies can be achieved even at high organic load values (2.4–2.6 kgCOD m−3 d−1) and with hydraulic retention times lower than one day. Furthermore, the treatment is characterized by a sludge production as low as 0.1 kg of dry sludge per kg of COD removed. Therefore, SBBGR has proved to be an effective pre-treatment for dyeing textile wastewater before discharge into municipal sewer system, as it produces a suitable effluent using just only one biological step with high hydraulic and organic loadings and low sludge production.

Bio-chemical treatment of medium-age sanitary landfill leachates in a high synergy system

Municipal landfill leachates are considered to be one of the types of wastewater with the greatest environmental impact because of the high concentrations of ammonium, organic matter and salts which characterize them. The most critical steps are usually the removal of recalcitrant pollutants and ammonia. A recently developed process based on ozone enhanced biological degradation, carried out in an aerobic granular biomass system (SBBGR – Sequencing Batch Biofilter Granular Reactor), was tested at lab-scale for treating a typical medium-age landfill leachate. The results have shown that ozonation greatly improves the biological treatment's effectiveness, allowing the current limits for discharging into the sewer system to be met by using a specific ozone dose of 600mg O3/Linfluent; an operating cost of about 4€ per m3 of leachate was obtained. A strong synergy between chemical and biological oxidation was observed with an O3consumed/CODremoved ratio as low as 0.24.Molecular analysis allowed the microbial composition of the granular biomass to be defined and showed the establishment of stable nitrogen-removing bacterial populations throughout the SBBGR operation. Moreover, the study further confirmed the SBBGR's ability to effectively overcome the problem of filamentous bacteria overgrowth, which, in contrast, dramatically affects the effluent quality in conventional systems.

Comparison of several combined/integrated biological-AOPs setups for the treatment of municipal landfill leachate: Minimization of operating costs and effluent toxicity

The treatment of medium-age landfill leachate was investigated by employing several set-ups including a sequencing batch biofilter granular reactor (SBBGR) step, with or without ozone enhancement, followed or not by a polishing stage with solar photo-Fenton (SphF). Objectives of the investigation were to compare different treatment strategies in order to achieve the lowest operating cost and to reduce the toxicity of the final effluent, evaluated by three different tests (respirometry, Vibrio fischeri and Lepidium sativum phytotoxicity). These objectives were addressed for two different target COD values, namely 160 and 500 mg/L, to be met in the final effluent for disposing of to water bodies and to sewers, respectively, requested by Italian environmental regulation. The different treatment strategies have demonstrated to be technically suitable for achieving the requested COD (160 or 500 mg/L) and reduction of the initial toxicity goals. For the COD target of 500 mg/L, the investigated treatment set-ups proposed in this paper showed to have comparable operating cost ( 3.2 € / m inf. 3 ). Instead, when the target COD is 160 mg/L, the combination SBBGR + SphF is economically more convenient ( 4.1 € / m inf. 3 ) being the operating cost of the other two investigated treatment set-ups (SBBGR/O 3 and SBBGR/O 3 + SphF) 5.7 and 4.8 € / m inf. 3 , respectively. As far as toxicity reduction is concerned, for both the COD target of 500 and 160 mg/L, the SBBGR/O 3 set-up gave better results than other investigated treatment options.

Sequencing batch biofilter granular reactor for textile wastewater treatment

Textile wastewater is difficult to treat as it usually contains considerable amounts of different pollutants, which are often recalcitrant, toxic and inhibitory. Therefore, complex treatment schemes based on the sequence of various steps are usually required for an effective treatment. This explains why textile effluents are often treated in centralized plants and sometimes mixed with municipal wastewater. The adoption of new technologies for on-site treatment, instead, would be optimal, deeply reducing treatment costs. An innovative technology exhibiting several characteristics appropriate for the attainment of such a goal is sequencing batch biofilter granular reactor (SBBGR). To assess the suitability of this technology, two lab-scale reactors were operated, treating mixed municipal-textile wastewater and a pure textile effluent, respectively. Results have demonstrated that mixed wastewater can be successfully treated with very low hydraulic retention times (less than 10 hours). Furthermore, SBBGR shows to be an effective pre-treatment for textile wastewater for discharge into sewer systems. The economic evaluation of the process showed operative costs of 0.10 and 0.19 € per m(3) of mixed wastewater and textile wastewater, respectively.

Effective treatment of stabilized municipal landfill leachates

An alternative process consisting of a pre-treatment step for nitrogen recovery as struvite followed by ozone enhanced biological degradation carried out in a SBBGR system (sequencing batch biofilter granular reactor) is proposed. The efficiency of the process in treating a mature municipal landfill leachate was tested at laboratory scale. The results show that for the same applied ozone dose, the plant performance was improved by shortening the ozonation phase time, due to higher ozone transfer efficiency. After optimization, the process was able to meet the COD limits for discharging into water bodies and sewer systems when a specific ozone dose of 2 and 0.6 g O 3/L influent, respectively, was used. The process was characterized by a negligible biological sludge production. The economic evaluation of the process showed operating costs of 9 and 6.5 € per m 3 of leachate for discharging into water bodies and sewer system, respectively. Additionally, in situ hybridization and staining techniques allowed the microbial composition and structure of the biomass growing under the different operating conditions of the SBBGR system to be defined. Microscopic analysis showed that ozone improves the biomass aggregation and lead to a substantial increase in biomass concentration (i.e., from 18 to 30 gTSS/L bed) and EPS content. SBBGR biomass was dominated by Gammaproteobacteria.

Biodegradation of Phenol by Immobilized in Peo-Cryogel Bacillus Laterosporus BT-271 in Sequencing Batch Biofilter

ABSTRACTA long (20 days) model process of phenol biodegradation was performed in biofilters in sequencing batch regime and with active biological system—polyethylene oxide cryogels (PEO-cryogel) with immobilized bacteria Bacillus laterosporus BT-271. The model waste water, containing mineral medium and phenol as the only source of carbon and energy with 300 mg/l in the effluent, was used. One of the key investigated parameters was the manner of immobilization of the bacteria in polyethylene oxide cryogels. The two variants of the experiment were: 1) direct immobilization of the inoculation material (SBB-D) and 2) inoculation of the biomass after preliminary separation and further concentration (SBB-S).The process was characterized on the basis of the following parameters: concentration of phenol in the influent, efficiency of phenol biodegradation, rate of phenol biodegradation, debit of purified water, loading of biofilters, rate of phenol degradation and efficiency, oxygenase enzyme activity of the cells immobilized in the cryogel and of the free cells in the effluent. The implantation of the gel with the immobilized microorganisms in a sequencing batch biofilter showed good biodegradation, kinetic, enzymological characteristics, as well as self-renovating adequate biofilm structure in laboratory conditions. The two biofilters functioned well and the efficiency of phenol elimination reached 100% in 15 days. The variant SBB-D showed a more stable process, as well as an easier way of preparing the initial PEO-plate biofilm. The SBB-D system is suitable for scaling and future implementation of the water purification processes in practice.

Sequencing batch biofilter granular reactor for textile wastewater treatment

Sequencing batch biofilter granular reactor for textile wastewater treatment

A chemically enhanced biological process for lowering operative costs and solid residues of industrial recalcitrant wastewater treatment

An innovative process based on ozone-enhanced biological degradation, carried out in an aerobic granular biomass system (SBBGR – Sequencing Batch Biofilter Granular Reactor), was tested at pilot scale for tannery wastewater treatment chosen as representative of industrial recalcitrant wastewater. The results have shown that the process was able to meet the current discharge limits when the biologically treated wastewater was recirculated through an adjacent reactor where a specific ozone dose of 120 mg O 3/L influent was used. The benefits produced by using ozone were appreciable even visually since the final effluent of the process looked like tap water. In comparison with the conventional treatment, the proposed process was able to reduce the sludge production by 25–30 times and to save 60% of operating costs. Molecular in situ detection methods were employed in combination with the traditional measurements (oxygen uptake rate, total protein content, extracellular polymeric substances and hydrophobicity) to evaluate microbial activity and composition, and the structure of the biomass. A stable presence of active bacterial populations was observed in the biomass with the simultaneous occurrence of distinctive functional microbial groups involved in carbon, nitrogen and sulphate removal under different reaction environments established within the large microbial aggregates. The structure and activity of the biomass were not affected by the use of ozone.

SBBGR technology for minimising excess sludge production in biological processes

This paper reports the results of an investigation aimed at evaluating the performance of an innovative technology (SBBGR system – Sequencing Batch Biofilter Granular Reactor), characterised by a low sludge production, for treating municipal wastewater at demonstrative scale. The results have shown that even at the maximum investigated organic load (i.e., 2.5 kg COD/m 3 d), the plant removed 80% of COD, total suspended solids and nitrogen content with relative residual concentrations lower than the Italian limits for discharge into soil. The process was characterised by a very low sludge production (i.e., 0.12–0.14 kg TSS/kg COD removed) ascribable to the high sludge age in the system (θc >120 d). Molecular in situ detection methods and microscopy staining procedures were employed in combination with the traditional measurements (oxygen uptake rate and total protein content) to evaluate both the microbial activity and composition, and the structure of the biomass. A stable presence of active bacterial populations (mainly Proteobacteria) was found within compact and dense aggregates.

Granular biomass structure and population dynamics in Sequencing Batch Biofilter Granular Reactor (SBBGR)

The aim of this paper is to study the microbial and structural changes occurring during the transition from flocculent (used as inoculum) to biofilm and granular sludge in a Sequencing Batch Biofilter Granular Reactor (SBBGR). SBBGR is a new and promising technology characterised by low sludge production (5–6 times lower than in conventional treatment plants), high biomass concentration (up to 35 g TSS/L bed), high COD conversion capacity, high effluent quality and operation flexibility. Molecular in situ detection methods and microscopy staining procedures were employed in combination with the traditional measurements (i.e., oxygen uptake rate, COD removal efficiency) to evaluate the microbial activity and composition of the granular biomass. The granules structure was investigated by electron scanning microscopy, phase contrast analysis of granule sections and specific extracellular polymeric substances (EPS) stainings. Evident changes in biomass composition was observed during the shift from activated to granular sludge while a stable presence of active bacterial populations (mainly Proteobacteria) was found within mature granules.

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/m 3 of treated wastewater) with interesting repercussions on treatment costs (about 1 € per m 3 of wastewater).

Removal of endocrine disrupter compounds from municipal wastewater by an innovative biological technology

The removal of selected endocrine disrupter compounds (EDCs), namely estrone(E1), 17beta-estradiol (E2), 17alpha-ethynylestradiol (EE2), bisphenol A (BPA) and 4-tert-octylphenol (4t-OP) from municipal wastewater was investigated using a sequencing batch biofilter granular reactor (SBBGR), a new system for biological treatment based on aerobic granular biomass. This new biological treatment is characterized by high biomass concentration (up to 40 g/L), high sludge retention times (up to 6 months) and low sludge production (i.e., an order of magnitude lower than commonly reported for conventional biological technologies). The investigation was carried out comparing a demonstration SBBGR system with a conventional full-scale activated sludge process. Results showed that the SBBGR performed better than a conventional activated sludge process in removing E1, E2, BPA and 4t-OP. In fact, the average removal percentages of the above mentioned EDCs, obtained during a four month operating period, were 62.2, 68, 91.8, 77.9% and 56.4, 36.3, 71.3, 64.6% for the demonstrative SBBGR system and the conventional activated sludge process of the municipal sewage treatment plant, respectively.

Technological transfer to demonstrative scale of sequencing batch biofilter granular reactor (SBBGR) technology for municipal and industrial wastewater treatment

The paper reports the results of an experimental investigation aimed at transferring to demonstrative scale an innovative technology (SBBGR-Sequencing Batch Biofilter Granular Reactor) for the treatment of municipal and industrial wastewater by financial support of the EU Life programme. When this technology was applied for treating municipal wastewater, the results showed that the system was able to remove 80-90% of COD, total suspended solids and ammonia independently of the hydraulic residence time investigated (i.e., from 12 to 4 h). In the case of tannery wastewater, chosen as representative of concentrated industrial wastewater, SBBGR technology was suitable for removing 80-90% of the COD, suspended solids and ammonia content up to organic loading values of 3.5 kg COD/m3.d. During both periods, the process was characterised by a very high sludge age value (theta(c) approximately 150 d) that led to a biomass concentration as high as 35 gTSS/L(bed) and a sludge production much lower (5-6 times lower) that than commonly reported for conventional treatment plants.

Removal of endocrine disrupter compounds from municipal wastewater using an aerobic granular biomass reactor

The removal of selected endocrine disrupter compounds (EDCs), namely estrone (E1), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), bisphenol A (BPA) and 4- tert-octylphenol (4t-OP) from municipal wastewater was investigated using a sequencing batch biofilter granular reactor (SBBGR), a new technology for biological treatment based on aerobic granular biomass. This new biological treatment is characterized by high biomass concentration (up to 40 g L −1), high sludge retention times (up to 6 months) and low sludge production (i.e., an order of magnitude lower than commonly reported for conventional biological technologies). The investigation was carried out comparing both a lab-scale SBBGR system and a demonstrative unit with a conventional full-scale activated sludge process. Results showed that the SBBGR, beside its already known benefits (removal efficiencies around 90% COD even at a high organic load (i.e., 5.7 kg COD m −3 d −1) and a sludge production value of around 0.06 kg TSS kg −1 COD removed), performed better than a conventional activated sludge process in removing E1, E2, BPA and 4t-OP. The average removal percentages of the above-mentioned EDCs, obtained during a 4-month operating period, were 60, 69, 93, 81% and 53, 41, 72, 67% for the demonstrative SBBGR system and the conventional activated sludge process of the municipal sewage treatment plant, respectively. In addition, lab-scale and demonstrative SBBGR systems showed similar efficiency for the removal of the investigated EDCs.