www.ccsenet.org/jsd Journal of Sustainable Development Vol. 4, No. 1; February 2011 ISSN 1913-9063 E-ISSN 1913-9071 112 Performance of Biological Filter with Bio Fillings for the Treatment of Municipal Waste Water Salam J. Bash Al-Maliky Environmental Engineering/ AlMustansiriya University- Iraq Faculty and Leader in Residence/ Ohio University-USA Zainab Qahtan ElKhayat Environmental Engineering/ AlMustansiriya University- Iraq Abstract Biological treatment of municipal waste water was tested via biological filter model of three different filling media; Wild Thorn, Arum Plant, and Date Palm Bark, separately. This was the first documented attempt, on the international level, of using these plants as fillings for biological filters. Tests were made for three different superficial flow rates (15, 30 and 45 m 3 /m 2 .d) for about four months, in order to consider the variations in ambient temperature. Good BOD 5 removal efficiencies were achieved by the use of these filling Medias. With a superficial flow rate of (15 m 3 /m 2 .d), efficiencies of about (76%, 71% and 62%) for Wild thorns, Arum Plant and Date Palm Bark, respectively, were attained under ambient temperatures of about 36-40 ₀ C, and (73%, 69% and 61%), in the same sequence, under 23-25 ₀ C. Also the constants (n and K) affecting the performance of biological filter, were determined. A problem of filter clog was indicated with the use of Date Palm Bark under high superficial flow rates (+ 30m 3 /m 2 .d). Also, high abundance of flies around the model was noticed with the use of all tested filling media. Keywords: Bio-Filling, Biological filter, Filter constant, Operational problems, Plant media Removal efficiency 1. Introduction One of the major approaches for the biological treatment of municipal and industrial wastewater was the biological filter system. The differences between alternative versions of this system were principally in the material used as the packing to provide the solid support for the film of microbial slime, and in the rate and manner in which the wastewater load was applied to the bed (El Nadi, 2005). Plastic media began to replace rock media when the demand for good rock media exceeded the supply. Poor quality rock media breaks down more rapidly and allow the microbial growths to clog the biological filter media. Overall economics soon favored plastic media over rock media (UNEP, 2002). The plastic media has allowed the use of tall filters and higher loading rates with about 50-80%, final efficiencies for the treatment of municipal and industrial wastewaters (Ross, 2004). Efficiencies of about 78%- 82%, were achieved in the treatment of industrial wastewaters adopting cheap, randomly distributed plastic fill media (Al-Maliky, 2002). These facts had paved the way to search for other possible replacements for the plastic media that are cheaper, more durable and available locally. New filling materials that may replace plastic should share almost all the properties that made plastic preferable for biological filters, such as, light weight, high specific surface area (surface area/ volume), high void ratio, cheap cost, chemical resistance, and mechanical durability(Smith, 2003). Many empirical models have been developed for the design of biological filters, as illustrated in Table 1. The removal of soluble BOD in biological filters with all media types can be expressed using Schultz formula: n Q e S e S / KD 0   (1) Where, S 0 , S e : filtered influent and effluent, BOD concentration (mg/l). A: the average geometric specific surface area of the particles (m 2 /m 3 ). D: Depth of filter (m). K: replacement for the term (k A B ). k: reaction rate constant. (d -(1-n) m -n ).