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Wang D.-b.,Hunan University | Wang D.-b.,Hunan Lvyuan Environmental Protection Engineering Co. | Zhang Z.-y.,Hunan Lvyuan Environmental Protection Engineering Co. | Li X.-m.,Hunan University | And 10 more authors.
Ecological Engineering

To explore an economical and manageable wastewater treatment process, a full-scale ecology filter integrated constructed rapid infiltration (Eco-CRI) was conducted and applied to treat freeway toll-gate domestic sewage, and the performances of Eco-CRI were investigated to evaluate its technical and economical suitability. The results showed that chemical oxygen demand, suspended solids, ammonia, and phosphorus could be removed efficiently when 1.0 m d-1 of the hydraulic loading rate and 2 h of dosing and 6 h of resting of feed regime were operated, respectively. Clogging, which was by far the biggest operational concern for the soil-based treatment systems, was not observed during the whole operation over a period of 14 months. Based on the results of economical analysis, electrical power consumption of per m3 wastewater treated was only 0.13 kWh. Besides maintenance of dosing pump, regular maintenance of Eco-CRI was just harvesting reeds and earthworms once a year. The facts indicated that Eco-CRI was a cost-effective and technically feasible process for freeway toll-gate domestic sewage treatment, and might serve as an attractive option for wastewater treatment in remote areas where regular maintenance was not feasible and/or in present developing countries like China where uneconomical approaches were not acceptable due to the local socioeconomic situation. © 2010 Elsevier B.V. All rights reserved. Source

Wang D.-B.,Hunan University | Wang D.-B.,Hunan Lvyuan Environmental Protection Engineering Co. | Zhang Z.-Y.,Hunan Lvyuan Environmental Protection Engineering Co. | Li X.-M.,Hunan University | And 12 more authors.
Water Science and Technology

Intermittent sand filters (ISFs) are effective and economical in treating wastewater, but they are easy to clog up. To explore a feasible and simple method to alleviate clogging, two pilot-scale ISFs were constructed, one of which contained earthworms and the other did not. During the operation, the effects of earthworms on the hydraulic behaviour of ISFs were investigated. The results showed that both ISFs exhibited good performance in wastewater treatment. However, they showed different hydraulic characteristics although operated at the same organic loading rate (approximately 300 gm -2d-1). The ISF without earthworms clogged only after 53 d operation, and was partially recovered after 7 d resting, but after that, clogging occurred again, and more rapidly than the initial clogging event (40 d). However, water on the medium surface of the ISF with earthworms was not observed during the whole experiments. In addition, 11-13% of effective porosity and 0.015-0.026cms21 of infiltration rate were measured in the upper 20cm of the ISF at the end of the experiments. The facts demonstrated that earthworms played a positive role in alleviating clogging and earthworms fed filter could alleviate surface clogging effectively. © IWA Publishing 2010. Source

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