Chen Li

A novel algal biofilm membrane photobioreactor for attached microalgae growth and nutrients removal from secondary effluent.

In this study, a novel algal biofilm membrane photobioreactor (BMPBR) equipped with solid carriers and submerged membrane module was developed for attached growth of Chlorella vulgaris and secondary effluent treatment. The volumetric microalgae production achieved in BMPBR was 0.072 g L(-1) d(-1), which was 1.44-fold larger than that in suspended growth membrane photobioreactor (MPBR). Furthermore, 72.4% of the total produced algal biomass was immobilized as algal biofilm in BMPBR. Advanced nutrients removal from secondary effluent was achieved both in BMPBR and MPBR, with average reduction of about 85% for PO4(3-)-P in the stable stage. Additionally, BMPBR showed better nitrogen removal performance than MPBR due to its higher algal biomass productivity. Moreover, with the filtration effect of the submerged membrane module in the reactor, suspended microalgae could be completely isolated from the effluent and a low average SS concentration of 0.28 mg L(-1) was achieved in the effluent of BMPBR.

Concentrated microalgae cultivation in treated sewage by membrane photobioreactor operated in batch flow mode

This study investigated the microalgae biomass production and nutrients removal efficiency from treated sewage by newly developed membrane photobioreactor in which Chlorella vulgaris was cultured in batch flow mode. Its performance was compared with conventional photobioreactor. The results show that the volumetric microalgae productivity was 39.93 and 10.36 mg L(-1)d(-1) in membrane photobioreactor and conventional photobioreactor, respectively. The nutrients removal rate in membrane photobioreactor was 4.13 mg N L(-1)d(-1) and 0.43 mg P L(-1)d(-1), which was obviously higher than that in conventional photobioreactor (0.59 mg N L(-1)d(-1) and 0.08 mg P L(-1)d(-1)). The better performance of membrane photobioreactor was due to the submerged membrane module in the reactor which acted as a solid-liquid separator and thereby enabled the reactor to operate with higher supply flow rate of cultivation medium. Moreover, in the outflow stage of the membrane photobioreactor, the microalgae culture liquor in the reactor could be further concentrated.

Saline domestic sewage treatment in constructed wetlands: study of plant selection and treatment characteristics

AbstractA series of investigations was conducted to treat saline domestic sewage using constructed wetlands. Twelve emergent plant species were planted in experimental units and fed with saline domestic sewage. All species were classified into three clusters using cluster analysis based on the average values of relative growth rate, nutrient uptake, root biomass and activity. The species of Cluster I, including Canna indica, Phragmites australis and Scirpus validus, had strong potential for the purification. The above plants were employed again to treat saline domestic sewage under different influent salinities concentrations. For the influent salinity of 0.5, 1.0 and 1.5%, average treatment performances of planted units were found to be 61.5–70.5% for COD, 59.3–68.4% for –N, 61.9–70.4% for TN and 40.4–47.3% for TP. With increasing influent salinity to 2.0%, the removal efficiencies were dropped significantly. It was similar to the change of the soil enzyme activity in the experiment units. Activities of ...

Study on saline aquaculture wastewater treatment by constructed wetland

Constructed wetland was used in this research for the treatment of saline aquaculture wastewater. Constructed wetland could removal organic matter and nutrient effectively. The planted unit showed better capability of COD, TN and TP removal than unplanted unit obviously. Treatment performance of planted unit was found to be 66.4–73.1% for COD, 62.4–72.4% for TN and 53.7–66.8% for TP. However the treatment performance of unplanted unit was found to be 55.2–60.3% for COD, 50.3–58.2% for TN and 48.7–59.7% for TP. The hydraulic loading rates have important effect on the removal efficiency of constructed wetland. When the hydraulic loading rate of the constructed wetland exceed 1 m/d, the removal rate of COD, NH<inf>4</inf>⁺-N and TN drop obviously. Then the reduction in COD, NH<inf>4</inf>⁺-N and TN was in the range of 47.6–62.3%, 52.3–66.3%, 50.2–60.3%, respectively.

Simultaneous nutrient removal and biomass/lipid production by Chlorella sp. in seafood processing wastewater

Microalgae cultivation in wastewater has received increasing attention in recent years due to its many advantages. In this work, microalgae were cultured in seafood processing wastewater (SPW) for algal biomass and lipid production as well as nutrient removal. The biomass yield of Chlorella sp. achieved in the batch cultivation was 896 mg L-1, indicating that SPW contains a certain amount of nutrients which can be used for the growth of microalgae. However, the maximum specific growth rate of Chlorella sp. cultured in SPW throughout the whole cultivation period was only 0.040 d-1, suggesting that the growth of algal cells was inhibited during the culture process. High concentration of unionized ammonia in the SPW was found to be a factor inhibiting the growth of Chlorella sp. Aerated SPW (ASPW) and diluted SPW (DSPW) proved to be better culture media than SPW without pretreatment. The maximum specific growth rates of Chlorella sp. cultured in ASPW and DSPW during the culture interval were 0.156 and 0.091 d-1, respectively. Aeration pretreatment of SPW reduced the amount of toxic unionized ammonia, while most of the nutrients were retained in the wastewater. Therefore, higher biomass productivity (77.7 mg L-1 d-1) and higher lipid productivity (20.4 mg L-1 d-1) of microalgae were achieved in ASPW. Additionally, improved nutrient removal rates from ASPW were also achieved due to the faster growth of microalgae. The average nutrient removal rates in ASPW during the whole cultivation period were 4.98 and 1.91 mg L-1 d-1 for nitrogen and phosphorus, respectively.