Ecological Engineering 35 (2009) 1249–1254 Contents lists available at ScienceDirect Ecological Engineering journal homepage: www.elsevier.com/locate/ecoleng In situ removal of contaminated suspended solids from a pond by filtration Tomohiro Inoue a , Masaharu Fukue b , Catherine N. Mulligan a,∗ , Koji Uehara c a Department of Building, Civil and Environmental Engineering, Concordia University, 1455 de Maisonneuve Boulevard West, Montreal, H3G 1M8, Canada b Department of Marine Civil Engineering, Tokai University, 3-20-1 Orido, Shimizu-ku, Shizuoka 424-8610, Japan c Soil Improvement Division, Japan Industrial Land Development Co. Ltd., 3-8-15 Kaigan, Minato-ku, Tokyo, 108-8432, Japan article info Article history: Received 31 October 2008 Received in revised form 3 April 2009 Accepted 19 May 2009 Keywords: Suspended solids Filtration Heavy metals Geotextile Phosphorus removal Algae abstract Suspended solids (SS) which have been discharged into ponds, lakes, and enclosed sea areas from shores and rivers absorb various substances such as heavy metals and nutrients. In this study, a small upward filtration system was developed to remove contaminated SS from the water. The system consisted of a main body with a flotation device, three pumps, two float sensors, solar panels and batteries. The filter medium consisted of a nonwoven geotextile with a thickness of 5mm. The pilot experiment was carried out in Shimizu Utozaka pond in Japan. SS, chemical oxygen demand (COD) and total phosphorus (T-P) removal efficiencies of 88.5%, 56.5% and 64.2% were obtained, respectively. In addition, the estimation of pollutant removal was determined from the amount of removed SS. This calculation enables not only the design of filtration systems for future individual cases, but also quantitative evaluation for the effect of restoration. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Various substances have been discharged into enclosed water areas such as lakes, ponds, and the enclosed sea areas from shores and rivers by natural and human activities. Suspended solids (SS) consisting of inorganic and organic substances have been dis- charged into water areas. It was reported by Hoshika et al. (1996) that the amount of SS discharged was over 200,000 tons during the summer in Osaka Bay in Japan. In addition, the amount of organic particles in the SS was approximately 150,000 tons (Hoshika et al., 1996). These SS which exist in the water cause a decrease in transparency and a reduction of dissolved oxygen. The reduction of dissolved oxygen in the bottom water and the sediment causes the anaerobic condition and results in the elution of reduction products such as heavy metals and nutrients from the sediment. Nutrient leaching from sediments can lead to eutrophication in the water. Eutrophication is one of the biggest environmental problems in enclosed water areas. It was noted by the World Health Organization (1999) that in the Asia Pacific Region, 54% of lakes are eutrophic. The proportions for Europe, Africa, North America and South America are 53%, 28%, 48% and 41%, respectively. Thus, eutrophication is a common and serious problem around the world. ∗ Corresponding author. Tel.: +1 514 848 2424x7925; fax: +1 514 848 7965. E-mail addresses: celsior412000@yahoo.co.jp (T. Inoue), fukue@scc.u-tokai.ac.jp (M. Fukue), mulligan@civil.concordia.ca (C.N. Mulligan), k uehara@kokusou.co.jp (K. Uehara). Algal blooms are also important problems for the environment in enclosed water areas (Codd et al., 2005). For example, cyanobac- teria (blue-green algae) which are found growing in lakes, ponds, and water reservoirs are known to produce toxins frequently (Codd, 1996; WHO, 1999; Fleming et al., 2002). The cyanobacterial tox- ins can cause the death of aquatic biota and also can harm human health through the intake of drinking water (Bell and Codd, 1994; Codd et al., 1997; WHO, 1999; Codd, 2000). There are currently not many treatment methods for recre- ational waters and the existing methods for algae control have not proven to be effective and may not follow the principles of ecologi- cal engineering and restoration. Ludwig et al. (2006) provided a list of eight principles as a framework for river cleanup. Among them are: do not harm, manage adaptively, use sound management and accommodate human prosperity. Mats of filamentous algae may be removed with a rake, screen wire, or a similar device, but tend to grow back as fast as they are pulled out. Addition of chemicals such as copper sulfate reduces the algae but should be used with caution with regards to domes- tic water, fish, swimming and irrigation. Existing in situ methods such as precipitation of phosphorus have not been successful (WHO, 1999). A biological control such as the introduction of non- indigenous plants may introduce more problems than the original pest. Wetland treatments have been used for the removal of nutri- ents from eutrophic water (Coveney et al., 2002) but their efficiency has not been proven for (phosphorous) P removal. Barley straw has been tested (Welch et al., 1990) for the control of planktonic and filamentous algae but results are very mixed, and no method 0925-8574/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.ecoleng.2009.05.006