open access

https://doi.org/10.14943/doctoral.k11576

https://hdl.handle.net/2115/57228

乾燥地域及び半乾燥地域における高速藻類池の研究

英語

2014-09-25

Hokkaido University

x,76

In recent years, large scale algal production has received lot of consideration due to the ability of algae to grow extremely rapidly and to accumulate a high quantity of lipid in their cells for biofuel production. For this purpose, algal photosynthetic growth is required and finding an economical and reliable method to produce and harvest algae feedstock remains a challenge. Thereby, apart from closed reactors used for algal production, the use of open ponds also known as high rate algal ponds which integrate wastewater treatment is nowadays emerging. For large scale biofuel production, HRAPs treating wastewater are recognized to be low cost than closed photobioreactors due to the easy operation and cost-effective construction.While the concern of algal biofuel production and wastewater treatment is currently increasing, this thesis focuses on the ability of HRAP to treat greywater and produce resources for agricultural activities in urban and peri-urban areas of arid and semi-arid countries. To tackle the increasingly severe issues related to water scarcity and domestic wastewater treatment in these areas, a greywater treatment system based on high rate algal pond (HRAP) was developed. As the conventional ponds, this technology is low cost, simple to build and operate. The HRAP is able to provide efficient wastewater treatment because of the assimilation of the wastewater nutrients into the algal biomass. Resources like biomass and energy can be recovered from the wastewater treatment for beneficial use. However, some negative points regarding the implementation of HRAP concern the large land area requirements and the washout of algae from ponds which increases the total suspended solids (TSS) concentration in the effluent. For an efficient wastewater treatment and recovery of resources usable in agriculture, the main purpose of this work consists to find operating strategies of HRAP leading to effective production and harvest of high settleable algal biomass.At a laboratory scale and under tropical conditions, several reactors simulating HRAP were set and various operated parameters based on the hydraulic retention time (HRT), solid retention time (SRT) and algal recycling were applied. In both reactors, the temperature was kept at 30±2 °C, the mixing of the reactor was performed to avoid algae sedimentation and LED lamps gave photosynthetic photon density varying from 430-550μmol-2s-1 at the surfaceiiiof the pond. The water qualities of synthetic greywater with their average values ±SD were: pH (6.76±0.45); T-N (12.41±3 mg/L); T-P (5.26±0.4 mg/L); TOC (22.69 mg/L). Samples withdrawn from influent tanks, HRAP, SBRs, CFRs and corresponding effluents tanks were collected once to twice per week and immediately analyzed. Total suspended solids (TSS) together with settleable solids were determined. Nitrogen and phosphorus species such as ammonium- nitrogen, nitrite, nitrate, total nitrogen, soluble reactive phosphorus and total phosphorus (T-P) were measured. As the treated effluent will serve for irrigation purpose, inactivation of E.coli in the system was also investigated.

2014-09-25

甲第11576号

博士(工学)

(主査) 教授 高橋 正宏, 教授 船水 尚行, 教授 岡部 聡, 准教授 佐藤 久

工学院（環境創生工学専攻）

博士論文

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