1- Bukuru, G., and Jian, Y. (2005) “Synchronous Municipal Sewerage-Sludge Stabilization.” J. of Environmental Sciences, 17 (1), 59-61.
2- Buys, B.R., Klapwijk, A., Elissen H., and Rulkens, W.H. (2008). “Development of a test method to assess the sludge reduction potential of aquatic organisms in activated sludge.” Bioresource Technology, 99 (17), 8360-8366.
3- Elissen, H.J.H. (2007). “Sludge reduction by aquatic worms in wastewater treatment with emphasis on the potential application of lumbriculus variegatus.” Ph.D. Thesis, Wageningen University, Netherlands.
4- Elissen, H.J.H., Hendrickx, T.L.G., Temmink, B.G., and Buisman, C.J.N. (2006). “A new reactor concept for sludge reduction using aquatic worms.” Water Research, 40(20), 3713 - 3718
5- Elissen, H.J.H., Mulder, W.J., Hendrickx, T.L.G., Elbersen, H.W., Beelen, B., Temmink, H., and Buisman, C.J.N. (2010). “Aquatic worms grown on biosolids: Biomass composition and potential applications.” Bioresource Technology, 101, 804-811.
6- Hendrickx, T.L.G., Temmink, H., Elissen, H.J.H., and Buisman, C.J.N. (2009). “Aquatic worms eating waste sludge in a continuous system.” Bioresource Technology, 100 (20), 4642-4648.
7- Hendrickx, T.L.G., Temmink, H., Elissen, H.J.H., and Buisman, C.J.N. (2009). “The effect of operating conditions on aquatic worms eating waste sludge.” Water Research, 43 (4), 943-950.
8- Kamiya T., and Hirotsuji, J. (1998). “New combined system of biological process and intermittent ozonation for advanced wastewater treatment.” Water Sci. Technol., 38, 145-53.
9- Moussavi, G., Asilian H., and Jamal, A. (2008). “Effect of ozonation on reduction of volume and mass of waste activated sludge.” J. of Applied Sciences Research, 4(2), 122-127.
10- Neyens, E., and Baeyens, J. (2003). “A review of thermal sludge pre-treatment processes to improve dewaterability.” J. of Hazardous Materials, 98, 51-67.
11- Rai, C.L., Stuenkmann, G., Mueller, J., and Rao, G.P. (2004). “Influence of ultrasonic disintegration on sludge growth reduction and its estimation by respirometry.” Environ. Sci. Technol., 38, 5779-5785.
12- Ratsak, C.H., and Verkuijlen, J. (2006). “Sludge reduction by predatory activity of aquatic oligochaetes in wastewater treatment plants: Science or fiction? A review.” Hydrobiologia, 564, 197-211.
13- Riedel, Jr., and David, J. (2009). “An investigation into the mechanisms of sludge reduction technologies.” M.Sc. Thesis, Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg.
14- Seungmin, N., Young-Uk, K., and Jeehyeong, K. (2006). “Physiochemical properties of digested sewage sludge with ultrasonic treatment.” Ultrasonic Sono-chemistry, 14, 281-285.
15- Song, B., and Xiaofei, C. (2009). “Effect of aeolosoma hemprichi on excess activated sludge reduction.” J. of Hazardous Materials, 162 (1), 300-304.
16- Vlyssides, A.G., and Karlis, P.K. (2004). “Thermal- alkalin solubilization of waste activated sludge as a Pre-treatment stage for anaerobic digestion.” J. Bioresource Technology, 91, 201-206.
17- Winters, R.O. (2004). Substantial reduction of organic waste streams using the natural food chain, Public Rep. 235, Agro-technology and Food Innovations B.V., 18 p, The Netherlands.
18- Zhang, G., Zhang, P., Yang J., and Chen, Y. (2007). “Ultrasonic reduction of excess sludge from the activated sludge system.” J. Hazard. Mater, 3, 515-519.
19- Zhu, M., Guo, M., Du, S., and Song, Y. (2011). “Sludge reduction induced by aquatic worms in SBR wastewater treatment system.” International Symposium on Water Resource and Environmental Protection (ISWREP), Xi’an, China, 1368-1371.