Zhenjia Zhang

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.

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.

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

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.

Simultaneous removal of ammonium and phosphate by zeolite synthesized from fly ash as influenced by salt treatment

As a typical refractory industrial wastewater, coal gasification wastewater has a high toxicity and poor biodegradability. In this paper, an anaerobic SBR–aerobic SBR process was used to treat coal gasification wastewater. Average removal efficiency of COD, total phenols, volatile phenols, NH4+–N were 65.1%, 79.6%, 99.5% and 99.39%, with final concentration in the effluent were 380 mg L−1, 45.2 mg L−1, 0.52 mg L−1 and 0.32 mg L−1, respectively. There are 72 kinds of organic matters in the influent, a total of 10 categories. After biological treatment, the types and concentration of organic matters in the effluent of A (anaerobic 48 h effluent), B (anaerobic 48 h–aerobic 48 h effluent), C (anaerobic 24 h effluent), D (anaerobic 24 h–aerobic 48 h effluent) has dropped significantly and the types of organic compounds were reduced to simpler 42, 45, 46 and 61 kinds, respectively. The process showed ascendancy in the treatment of toxic matters. Organics degradation and transformation were analysed by GC-MS. Additionally, microbial community analysis in anaerobic sludge was investigated by means of polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) along with SEM, revealed that it had a great variety of bacterial dominant species. The study demonstrated that hydrolytic acidification at SBR anaerobic 24 h + aerobic 48 h could be a technically feasible method to enhance NH4+–N, COD, TP removal and degradation of complex organic compounds in coal gasification wastewater.