Atsuhiro Honda

Tertiary treatment of leachate from a sea‐based solid waste disposal site

Abstract Biologically pretreated leachate from a sea‐based solid waste disposal site was treated using carbon adsorption, ozonation and chemical coagulation. CODp in the leachate was hardly removed by activated carbon. The constants of k and 1/n in Freundlich isotherm equation were 0.069 and 2.0, respectively. Ozone oxidation was found ineffective. Ozone‐CODp binding coefficient was 0.019 i.e. about 10 times lower than that of sewage and septage. Ferric chloride and polymerized ferric sulfate were found to be effective in decreasing CODp. Maximum removal efficiency attained was 50%.

Study on the Solid-liquid Separation of Wastewater with a Rotating Drum Screen

本研究では, ドラムタイプの微細スクリーンによる排水の固液分離において, 駆動装置が不必要なブラシを用いた目詰まり防止方法, 分離汚泥の濃縮方法, およびスクリーンの固液分離特性について実験的に検討した。実験の結果, 目開き100μmのウェッジワイヤーを用いた濾過筒が本処理法に適切であることがわかった。また, ブラシを用いた目詰まり防止を行い, 100μm濾過筒の場合, メンテナンスフリーで6ヵ月間継続して運転が可能になり, SS除去率が13～47% (平均30%), BOD除去率が4～41% (平均22%) であった。発生する濾滓は, 数cmの塊状になり, スクリーンから自動的に排出された。含水率が86.5～92.5%とかなり低い値であった。さらに, 各々の濾過筒の処理可能水量の算定式を提示し, 最初沈殿池を用いた場合と比較した。

LEACHATE CHARACTERISTICS FROM SEWAGE SLUDGE LANDFILLS COVERED WITH IMPERMEABLE MEMBRANES

ABSTRACT To evaluated the covering method, two different types of pilot-scale lysimeters were constructed out-of-doors. Each lysimeter was filled with a mixture of sewage sludge dehydrated with lime and soil (decomposed granite soil). Lysimeter A was covered with an impermeable membrane and lysimeter B was left uncovered. Though BOD 5 and total nitrogen concentrations of lysimeter A were still at high levels throughout the 15-month experiment, the total amount of leachate of lysimeter A was about 1/4 time as much as that of lysimeter B. Besides, lysimeter As cumulative loads of BOD 5 and T-N were less than half the value of lysimeter B. Judging from the TOC and lower-molecular organic acid concentrations, it was considered that biological decomposition in lysimeter A was delayed. In the batch experiment with activated sludge, the BOD 5 removal rate coefficient of leachate from lysimeter A was 1.9 × 10 −4 (1/mgSS/hr.). This value and the Gel-Permeation Chromatogram patterns showed that the biodegradability of leachate was the same as that of the municipal sewage.

Advanced treatment of high-strength wastewater by a submerged bio-film process

Abstract A submerged bio-film process was studied as a tertiary treatment to decrease the BOD of secondary effluent from a combined chemical-biological treatment of high-strength wastewater to below the permitted limit (30 mg/ l ) for waste facilities in Japan. The operational conditions to keep the final effluent below 30 mg/ l of BOD were as follows: the influent BOD to the bio-film tank should be under 300 mg/ l and a BOD-surface loading should be below 2 g/m 2 /d. The influent pH of 9.0–12.5 did not affect the treatment efficiency unfavorably. Acclimation is the compensating factor for variations of pH in this process. Removal rates of suspended solids were not influenced by BOD-surface loading. The calculated BOD removal coefficient was 2.57 × 10 −5 when the influent BOD was below 300 mg/ l .