Salma Tabassum

An advanced anaerobic expanded granular sludge bed (AnaEG) for the treatment of coal gasification wastewater

A state-of-the-art advanced anaerobic expanded granular sludge bed (AnaEG) was developed for the anaerobic treatment of coal gasification wastewater (typical industrial wastewater with poor biodegradability and high toxicity). Three batch tests were conducted to check the efficiency of the reactor. The reactor was run for 330 days using acidification, with a final hydraulic retention time (HRT) of 48 hours. With an influent concentration of chemical oxygen demand (COD) of 1400 mg L−1, 320 mg L−1 total phenol , and 150 mg L−1 volatile phenol, the effluent COD, total phenol, and volatile phenol could be decreased to 800 mg L−1, 200 mg L−1 and 40 mg L−1, respectively. The AnaEG shows a COD removal efficiency of 50%, with a loading rate of 0.806 (kg COD per m3 per day), a removal rate of 0.357 (g COD per day), total phenol removal efficiency of 50%, and a volatile phenol removal efficiency of 80%. Besides being able to remove 70–95% of organic matter from the wastewater, this technology generates less sludge. Finally, scanning electron microscopy (SEM) revealed long-chain filamentous bacteria; coccus and rod-shaped bacteria were the dominant microorganisms. A CH4 production rate of 227.23 (ml CH4 per L per day) during a loading rate of 626.25 (mg COD per L per day) and a removal rate of 87.68 (mg COD per L per day) was observed. The significant reduction in the amount of sludge produced therefore reduces the sludge management cost. It does not have to reflux; this equipment is simple as it requires less accessory equipment and lower power consumption, and produces a high quality effluent. All the results demonstrate that the AnaEG could be used efficiently for the treatment of coal gasification wastewater containing high COD and phenol concentration.

An advanced anaerobic biofilter with effluent recirculation for phenol removal and methane production in treatment of coal gasification wastewater.

An advanced anaerobic biofilter (AF) was introduced for the treatment of coal gasification wastewater (CGW), and effluent recirculation was adopted to enhance phenol removal and methane production. The results indicated that AF was reliable in treating diluted CGW, while its efficiency and stability were seriously reduced when directly treating raw CGW. However, its performance could be greatly enhanced by effluent recirculation. Under optimal effluent recirculation of 0.5 to the influent, concentrations of chemical oxygen demand (COD) and total phenol in the effluent could reach as low as 234.0 and 14.2mg/L, respectively. Also, the rate of methane production reached 169.0mLCH4/L/day. Though CGW seemed to restrain the growth of anaerobic microorganisms, especially methanogens, the inhibition was temporary and reversible, and anaerobic bacteria presented strong tolerance. The activities of methanogens cultivated in CGW could quickly recover on feeding with glucose wastewater (GW). However, the adaptability of anaerobic bacteria to the CGW was very poor and the activity of methanogens could not be improved by long-term domestication. By analysis using the Haldane model, it was further confirmed that high effluent recirculation could result in high activity for hydrolytic bacteria and substrate affinity for toxic matters, but only suitable effluent recirculation could result in high methanogenic activity.

A high efficiency biological system for treatment of coal gasification wastewater – a key in-depth technological research

Coal is the main energy resource in China, hence pollution caused by coal gasification wastewater has been severe for decades. A three stage system was adopted to treat coal gasification wastewater; anaerobic hydrolysis acidification (333 days), aerobic oxidation (300 days), and ozonation–aerobic fluidized bed process (220 days) with the lowest HRT of 45 h. After more than a year of trials, high efficiency and stability of the treatment process has been achieved and the results showed that with an average influent (COD 4400 mg L−1, total phenol 950 mg L−1, volatile phenol 530 mg L−1, NH4+–N 300 mg L−1, volatile acids 120 mg L−1 and high chromaticity color blow 1000 times), the effluent COD could decrease to <60 mg L−1, and total phenol, volatile phenol, NH4+–N, and volatile acids were not detected, and for the chromaticity, the higher color removal reached to 10 times showed an average removal efficiency of COD, total phenol, volatile phenol, NH4+–N and volatile acids of 96%, 99.9%, 99.9%, 99.9% and 99.9%, respectively. The pollutants removed were converted to biogas; organic transformations in the system were analysed by GC/MS equipment. The power consumption and the amount of sewage sludge were reduced by 30%. The wastewater treatment cost is 0.135

A novel environmental biotechnological aerobic process (BioAX) for the treatment of coal gasification wastewater

per m3. This study can be used to build a test to simulate future engineering applications of small scale technology platforms as it is a short, simple processing unit, with low energy consumption, low sludge production and easy management and maintenance.

Novel Mass Bio System (MBS) and its potential application in advanced treatment of coal gasification wastewater

A high efficiency advanced bio-membrane technology aerobic reactor (BioAX) has been investigated for the treatment of coal gasification wastewater over a period 300 days. It could treat the coal gasification wastewater effectively after a post anaerobic process. With the influent conc. of COD 800–900 mg L−1, total phenol 100 mg L−1, ammonium nitrogen 80–100 mg L−1, and volatile phenol 40 mg L−1, the effluent COD, total phenol, ammonium nitrogen, and volatile phenol could decrease to 200–300 mg L−1, 20 mg L−1, 15–30 mg L−1 and 1 mg L−1 showing average removal efficiencies of COD, total phenol, ammonium nitrogen, and volatile phenol of 70–80%, 80%, 70–80%, and 99.9%, respectively. The loading rate and removal rate of total phenol showed a linear relationship having R2 = 0.95169. The technology also substantially reduces the sludge quantity and thus reduces the sludge handling cost. After 300 days of continuous operation, scanning electron microscopy (SEM) revealed the formation of biofilm by the microbial population as well as intensive filamentous bacteria settlements on the biological filler. Moreover it has a durable aeration system that is easy maintained and can be easily replaced. It can treat low to medium contents of organic or biological waste.

Anaerobic ammonium oxidation (ANAMMOX) sludge immobilized by waterborne polyurethane and its nitrogen removal performance-a lab scale study

In this study, a Novel Mass Bio System (MBS), a suspended biologically activated carbon granular carrier cubic particle with 2–5mm side length and 1.02–1.08 specific gravity was developed for advanced treatment of coal gasification wastewater. A laboratory scale anaerobic AnaEG (advanced anaerobic expanded granular sludge bed)–primary aerobic BioAX (a novel environmental biotechnological aerobic process with internal circulation)–MBS aerobic fluidized bed nitrification bioreactor–MBS expended bed denitrification bioreactor–secondary aerobic BioAX reactor system was operated over a period of 260 days. With an influent concentration of chemical oxygen demand (COD) 3000 mg L−1, total phenol (TP) 300 mg L−1, and ammonium nitrogen (NH4+-N) 149 mg L−1, the effluent COD, TP, NH4+-N, could be decreased to 159 mg L−1, 6 mg L−1 and 0.12 mg L−1, respectively. The maximum removal efficiencies of COD, TP, and NH4+-N were respectively 94.7%, 98%, and 99.9%. With hydraulic retention time (HRT) of 36 h, methane content was 60% and methane productivity was 0.11 L CH4/g COD. Pyrosequencing analysis showed the enrichment of ‘rare microbes’. Contrary to expectation, nitrifying bacteria, Ohtaekwangia (Bacteroidetes) was the most abundant rare bacteria with 37.1% of the microbial community entrapped in MBS.

Determination of biological removal of recalcitrant organic contaminants in coal gasification waste water

In the present study, to maintain the biomass of anaerobic ammonium oxidation bacteria (ANAMMOX) in water, waterborne polyurethane (WPU) was used to immobilize ANAMMOX sludge. The ANAMMOX granules immobilized by WPU exhibited the best entrapment support, superb bioactivity and highest mechanical stability when compared with the performance of other ANAMMOX immobilized granules of polyvinyl alcohol (PVA), sodium alginate (SA), and the mixed material, PVA–SA. In a continuous-flow experiment, during high volume-load WPU-immobilized granules exhibited a relatively high total nitrogen removal rate, no effluent suspended solids or granule crushing were observed within 100 days. The highest total nitrogen removal rate of 80.98% was observed when the volume load of TN was 1.697 kg per m3 per day with HRT 1.5 h. WPU-immobilized granules exhibited better correlation (R2: 0.945 NH4+–N and 0.989 NO2−–N) with experimental kinetic data for biological nitrogen removal. According to experimental data, good sludge retaining ability, strong resistance to shock-loading and mechanical stability during long-term operation of the granules immobilized by WPU was observed. The formation of volcanic crater-like concaves on the two sides of each bacterium and a large amount of ANAMMOX bacteria growing along the channels inside of the WPU granules were observed by scanning electron microscopy. Finally, the microbial community analysis 16S rDNA cloning revealed that Candidatus Brocadia fulgida (JX243641.1) was the primary ANAMMOX bacteria inside the WPU-immobilized granules. As carriers, immobilization materials protect ANAMMOX bacteria and increase biomass; however, they have no effect on bacteria and bacterial community structure.

Effect of effluent recirculation rate on the performance of anaerobic bio-filter treating coal gasification wastewater under co-digestion conditions

Coal gasification waste water treatment needed a sustainable and affordable plan to eliminate the organic contaminants in order to lower the potential environmental and human health risk. In this paper, a laboratory-scale anaerobic–aerobic intermittent system carried out 66 operational cycles together for the treatment of coal gasification waste water and the removal capacity of each organic pollutant. Contaminants included phenols, carboxylic acids, long-chain hydrocarbons, and heterocyclic compounds, wherein the relative content of phenol is up to 57.86%. The long-term removal of 77 organic contaminants was evaluated at different hydraulic retention time (anaerobic24 h + aerobic48 h and anaerobic48 h +aerobic48 h). Contaminant removal ranged from no measurable removal to near-complete removal with effluent concentrations below the detection limit. Contaminant removals followed one of four trends: steady-state removal throughout, increasing removal to steady state (acclimation), decreasing removal, and no removal. Organic degradation and transformation in the reaction were analysed by gas chromatography/mass spectrometry technology.

Screening of facultative strains of high lipid producing microalgae for treating surfactant mediated municipal wastewater

In this paper, anaerobic biofilters (AF) were adopted for anaerobic co-digestion of potato starch wastewater (PSW) and coal gasification wastewater (CGW). A modified Gompertz equation was used for the analysis. With a ratio of PSW:CGW at 1:1 for the influent, it remarkably improved the removal effect of (chemical oxygen demand) COD and total phenol. With an influent concentration of COD of 2600 mg L−1 and total phenol 200 mg L−1, the effluent COD and total phenol could be decreased to 1100 mg L−1 and 100 mg L−1, respectively. The methane production rate was generally above 260 (mL CH4 per g per d). In order to further enhance the performance of the system, the strategy of effluent recirculation on co-digestion was adopted. The result indicated that under a low effluent recirculation rate of 0.5, concentrations of COD and total phenol in effluent could reach as low as 800 and 70 mg L−1, respectively. Also, the methane production rate was around 300 (mL CH4 per g per d). High-throughput sequencing showed the microbial phyla Bacteroidetes, Chloroflexi, Euryarchaeota, Firmicutes dominanted the system and the abundance variation was observed at different effluent recirculation rates.

Treatment of coal gasification wastewater by anaerobic SBR–aerobic SBR process for elimination of toxic organic matters-a lab scale study

This study discusses a novel approach to simultaneously remove two types of hazardous chemicals, surfactants and nutrients, from municipal wastewater by culturing selected microalgae. A total of 76 strains of microalgae were separated from different sampling sites situated in the Island of Penang, Malaysia, using a 48-well tissue culture plate. Screening and acclimation procedures were performed to select facultative heterotrophic microalgae strains capable of growing in surfactant-mediated wastewater for simultaneous wastewater treatment and lipid production. Only eleven out of thirty-six facultative strains were demonstrated to be tolerant towards surfactant-mediated municipal wastewater (SMMW). The selected eleven strains were further characterized according to the rate of cell growth, biomass production, lipid accumulation and fatty acid profile. The six best strains, identified as Scenedesmus sp., Chlamydomonas sp., Chlorococcum humicola, Botryococcus braunii and two Chlorella sp., were chosen for further studies because of their ability to grow in surfactant mediated municipal wastewater (SMMW) with high growth rates (0.354–0.501 d−1) and their higher lipid accumulations (21.54–41.98% of dry biomass).