Advanced Materials Research Vol. 777

Abstract: Microalgae are a promising feedstock for biodiesel production. Microalgal biodiesel can be obtained under three major cultivation modes, namely, photoautotrophic, heterotrophic, and mixotrophic cultivation. Reported studies of microalgal biodiesel production are mainly based on photoautotrophic cultivation, mixotrophic cultivation has rarely been researched. This paper compared the biomass productivity, lipid content, and lipid productivity of Scenedesmus sp. under photoautotrophic, heterotrophic, and mixotrophic cultivation. Glucose was added as organic carbon source at five concentrations (0.1, 0.5, 1.0, 2.0, 5.0% glucose w/v). Results displayed that microalgal growth was significantly improved in glucose supplied cultures. Synergetic effect of photoautotrophy and heterotrophy existed in all mixotrophic cultures. Highest biomass productivity of 1.307 g·L^-1·d^-1 and highest lipid productivity of 316 mg·L^-1·d^-1 was respectively observed under mixotrophic cultivation with 5.0% and 1.0% (w/v) glucose addition. Lipid content of Scenedesmus sp. under mixotrophic cultivation was mostly higher in stationary phase than in exponential phase. Highest lipid content of 27.73% was observed in 1.0% mixotrophic culture, followed by 24.66% in 1.0% heterotrophic culture.

Abstract: ALB integration is consisted of anaerobic hydrolysis regulating, anaerobic aerobic reaction, air-lift reflux circulating and suspension clarifying precipitate. It is a new compact energy-saving technology of active sludge nitrogen and phosphorus removal. Its properties include shorter flow path, less land used, lower construction cost, lower operation cost, less discharge sludge, easier management, more reliable operation and so on. It propitious to be used for small-scale sewage treatments.

Abstract: The two-stage mode was used to start up the denitrifying dephosphatation system with nitrite as electron acceptor, and the systems capability of denitrifying dephosphatation was evaluated. Phosphate-accumulating organisms were enriched under the anaerobic/aerobic condition at the first stage. Then change the condition to anaerobic/anoxic so that denitrifying phosphate-accumulating organisms (DPAO) using NO₂-N as electron acceptor can be selected. The fast start-up of this system was achieved after 120 days, and the system has a good capability of denitrifying dephosphatation. The average TN and TP in the effluent were 5.39 mg/L and 1.55 mg/L with removal rates of 82.5% and 80.0%, respectively. PCR-DGGE results showed that microbial population changed in the process of domestication, while the structure of microbial community changed little in the stable stage, indicating relatively stable microbial community structure had formed after the domestication.

Abstract: To strengthen the COD removal from actual coking wastewater, a lab-scale granular bio-film reactor was continuously operated at three stages for about 9 months: anaerobic vs. micro-aerobic (over 2 months), with and without supplement of bicarbonate (over 2 months), and with and without supplement of diatomite (about 4 months).Compared with anaerobic condition, the micro-aerobic operation could strengthen COD removal in the actual coking wastewater and increase COD removal efficiency from 21.4% to 36.4%. At micro-aerobic operation conditions, the supplement of 3g.L_influent^-1 bicarbonate could distinctly increase COD average removal efficiency from 32.9% to 65.3%, and the supplement of 6g·L^-1·d^-1 diatomite could significantly increase COD average removal efficiency from 33.1% to 78.1%. The supplement of bicarbonate or diatomite for the granular bio-film reactor must be an effective way for the treatment of actual coking wastewater.

Abstract: The removal effect of raw wastewater treatment by anaerobicSBR was investigated, and the removal effects of wastewater COD, ammonia and orthophosphate were studied. Then the raw wastewater decolonization was implemented. The results showed that influent COD, ammonia and orthophosphate was at about 2000 mg/L, 80.7 mg/L and 7.1 mg/L, the removal efficiency of COD, ammonia and orthophosphate was at 96.5%, 95.3% and 97.2% respectively. When the raw wastewater color is about 200 times with PAC adding dosage 10~40 mg and activated carbon adding dosage 1.5~3.0 g, the effluent color can decrease lower than 50 times.

Abstract: Membrane bio-reactor (MBR) is an innovative and effective wastewater treatment process, which has much more extra advantages than other processes. However, membrane fouling and high operational/maintenance costs are always two important factors that restrict the development of MBR. In order to alleviate membrane fouling, larger aeration rate is usually used, which increases the operational cost and decrease N and P removal efficiencies of MBR. This paper summarizes the pilot scale experimental study on the improvement of operational performance of MBR by its design modification from one cell into three cells with micro-aeration,normal aeration and enhanced aeration conditions respectively with the package of fibrous bio-film carrier and PAC. As the result, the effluent water quality was improved significantly and membrane fouling was alleviated remarkably.

Abstract: The influence of MLSS on nitrosation denitrifying phosphorus removal (NDPR) process was investigated through the experiments of anaerobic-anoxic NDPR and anoxic NDPR. Experimental results show that the higher MLSS is, the bigger COD removal rate is, and the higher the rates of anaerobic phosphorus release and anoxic phosphorus absorption are. Low carbon sewage will easily lead to insufficient inner carbon source in the system with high MLSS. High concentration of carbon source in the raw water with high MLSS will bring considerable difficulties to returned sludge and sludge treatment. Moreover, excessive MLSS will result in phosphorus release in the later anoxic stage, and lower MLSS can prolong the time of denitrification and phosphorus removal. The system with 5200 mg/L MLSS has the best effect of nitrogen and phosphorus removal.

Abstract: Papermaking wastewater mainly consists of black liquor, intermediate wastewater and white water. It suffers from its heavy amount, high level suspended solids and poor biodegradable property. In this paper, a combination of fixed bed and moving bed biofilm reactor was conducted to treat paper making wastewater in order to make full use of the advantages of both fixed bed and moving bed. As a result, the average values of COD, NH₃-N and SS in effluent are 57.01 mg/L, 1.74 mg/L and 38 mg/L, respectively. The quality of the effluent could meet the demands of the Chinese standards for papermaking industrial water discharge pollutant.

Abstract: Both qualitative and quantitative analysis of intracellular polymers in polyphosphate accumulating organisms (PAOs) was discussed in this paper. Results were indicated that black-blue particles of poly-β-hydroxyalkanoate (PHBs) were observed clearly by Sudan black staining. DAPI staining and the Neisser new staining for polyphosphate (poly-P) were more proper than other staining methods. PHB content reached 198.3 mg/g MLSS detected by GC. After digested by HClO₄, the poly-P content of sludge was determined to be 138.4 mg/g MLSS.

Abstract: The performance of a pilot scale combined process of facultative contact reactor-biological contact oxidation and ozone biological aerated filter (FCR-BCO-O₃-BAF) treating real textile wastewater was investigated in this study. During the operating period, the average influent and effluent COD concentrations were 737.0mg/L and 15.6mg/L, the influent and effluent color were 750 times and 10 times, with the total HRT being 43.3h. The average COD and color removal efficiency were 97.9% and 98.7%, respectively. And the effluent COD and color satisfied the discharge standards (grade-1) of water pollutants for dyeing and finishing of textile industry (China). In the operating conditions, HRT of O₃-BAF was decreased, leading to an increase of the effluent COD concentration. In addition, under the facultative circumstance by micro aeration in the FCR, where the dissolved oxygen (DO) was maintained in the range of 0.1-0.3mg/L, the growth of sulfate reducing bacteria (SRB) was inhibited. This study is a significant attempt to apply the combined process of FCR-BCO-O₃-BAF to textile wastewater treatment.