Wastewater sludge contains high levels of organic matter and significant amounts of essential nutrients and trace elements for plant growth. Moreover, sludge can be considered a slow-release fertilizer as a result of its high concentration of organic nitrogen (N) (Davis, 1989; Kocaer et al., 2003). Plant-available nutrients such as N and phosphorous (P) in wastewater sludge could be used as a replacement for conventional fertilizers in agricultural production (Casado-Vela et al., 2006; Moreda et al., 1998). Therefore, wastewater sludge is recycled for agricultural purposes in many countries.
Wastewater sludge is rich in organic compounds and several plant nutrients. However, the reuse of sludge must be performed under conditions that limit the risks associated with pathogenic microorganisms present in the sludge. Sludge may contain pathogenic bacteria, viruses, and protozoa along with other parasitic helminths, which are hazardous to the health of humans, animals, and plants (Pescod, 1992). The reuse of agricultural sludge is only acceptable if the sanitary quality is guaranteed and public concern is limited. Because the presence of fecal coliforms in sludge directly relates to fecal contamination and the implied threat of the presence of enteric disease agents, limitations for fecal coliform bacteria are included in EU and U.S. sludge directives. To demonstrate that a given sludge meets U.S. Environmental Protection Agency (USEPA) Class B pathogen requirements, the density of fecal coliform bacteria from at least seven samples of sun-dried wastewater sludge (SDS) must be determined, and the geometric mean of the fecal coliform density must not exceed 2 million colony-forming-unit (CFU) or most probable number (MPN) per (dry weight) gram of total solids (USEPA, 2003).
The results of several studies indicated that land application of untreated sludge introduces large amounts of bacteria to leachates and soil (Kocaer et al., 2004). Moreover, heavy or toxic metals in the sludge threaten crop yields and long-term soil quality (Gardiner et al., 1995). For instance, some plants accumulate high concentrations of heavy metals (Singh and Agrawal, 2007). Therefore, these metals restrict the use of sludge for agricultural purposes (Dai et al., 2007; Udom et al., 2004).
Despite the considerable reduction in the levels of microbial organisms during the sludge treatment process (such as air drying and pasteurization), certain microbes may regrow in the sludge after the treatment is complete (Alkan et al., 2007). After the drying process, the regrowth risk is especially high, and nutrients in dried sludge are likely to enhance the regrowth of bacteria under certain conditions. Gibbs et al. (1997) suggested that the repopulation of fecal coliform bacteria occurred in soil amended with sludge after rainfall.
Few studies on the application of sludge as a soil amendment for turfgrass production have been conducted. Nevertheless, the results of a previous study demonstrated that turf quality increases with an increase in the timing and rate of composted sludge amendments during sod establishment (Angle et al., 1981). The observed increase in turfgrass quality was attributed to the presence of sufficient amounts of available nutrients in sewage sludges. The color of turfgrass produced from composted-sewage sludge amendments was comparable to that of turfgrass fertilized with ammonium nitrate (Angle, 1994; Markham, 1998). Moreover, if turfgrass receives adequate supplemental N, P, and potassium (K), deinked and primary-paper sludges can be effectively used as soil amendments to pure kentucky bluegrass (Poa pratensis L.) and kentucky bluegrass–perennial ryegrass (Lolium perenne L.) mixtures (Norrie and Gosselin, 1996). In greenhouse studies, the addition of 10% to 20% composted sewage sludge to plastic bins greatly improved the soil nutrient supply and turfgrass growth without significantly affecting soil heavy metal and soluble salt concentrations (Cheng et al., 2007). In South Africa, sludge obtained from a municipal water treatment plant was applied at a rate of 0, 8, 33, 67, and 100 mg·ha−1 of oven dry sludge in sod production of kikuyu (Pennisetum clandestinum Hochst. ex Chiov.). The results indicated that the sludge applications significantly increased the turfgrass establishment rate and color (Tesfamariam et al., 2009).
The objectives of the present study were to 1) determine the effects of the rate and timing of SDS applications on turfgrass growth and quality and to 2) measure the change in the concentration of heavy metals [lead (Pb), cadmium (Cd), copper (Cu), nickel (Ni), zinc (Zn), and mercury (Hg)], total N, nitrate, and ammonium N concentrations, available P, exchangeable K, soil pH, organic carbon, electrical conductivity (EC), and Escherichia coli count in turf soils after SDS application.
Alkan, U., Topaç, F.O., Birden, B. & Baskaya, H.S. 2007 Bacterial regrowth potential in alkaline sludges from open-sun and covered sludge drying beds Environ. Technol. 28 1111 1118
Angle, J.S. 1994 Sewage sludge compost for establishment and maintenance of turfgrass 45 51 Leslie A.R. Handbook of integrated pest management for turf and ornamentals Lewis Boca Raton, FL
Bilgili, U. & Acikgoz, E. 2005 Year-round nitrogen fertilization effects on growth and quality of sports turf mixtures J. Plant Nutr. 28 299 307
Bossche, V.H. 2000 Phosphorus losses from sewage sludge disposed on a field: Evidence from storm event simulations Water Sci. Technol. 42 179 186
Bremner, J.M. & Mulvaney, S.S. 1982 Nitrogen-total 595 622 Page A.L., Miller R.H. & Keeney D.R. Methods of soil analysis, Part 2. Chemical and microbiological properties 3SSSA Book Ser. 9. SSSA and ASA Madison, WI
Casado-Vela, J., Selle, S. & Navarro, J. 2006 Evaluation of composted sewage sludge as nutritional source for horticultural soils Waste Manag. 269 946 952
Cheng, H., Xu, W., Liu, J., Zhao, Q., He, Y. & Chen, G. 2007 Application of composted sewage sludge (CSS) as a soil amendment for turfgrass growth Ecol. Eng. 29 96 104
Dai, J.Y., Xu, M.Q., Chen, J.P., Yang, X.P. & Ke, Z.S. 2007 PCDD/F, PAH and heavy metals in the sewage sludge from six wastewater treatment plants in Beijing, China Chemosphere 66 353 361
European Union 1986 Council Directive of 12 June 1986 on the protection of the environment, and in particular of the soil, when sewage sludge is used in agriculture (86/278/EEC)
Gardiner, D.T., Miller, R.W., Badamchian, B., Azzari, A.S. & Sisson, D.R. 1995 Effects of repeated sewage sludge applications on plant accumulation of heavy metals Agr. Ecosyst. Environ. 55 1 6
Gibbs, R.A., Hu, C.J., Ho, G.E. & Unkovich, I. 1997 Regrowth of faecal coliforms and salmonellae in stored biosolids and soil amended with biosolids Water Sci. Technol. 35 269 275
Keeney, D.R. & Nelson, D.W. 1982 Nitrogen-inorganic forms 643 693 Page A.L., Miller R.H. & Keeney D.R. Methods of soil analysis, Part 2. Chemical and microbiological properties SSSA Book Ser. 9. SSSA and ASA Madison, WI
Kocaer, F.O., Alkan, U. & Baskaya, H.S. 2004 The effect of alkaline stabilized sludge application on the microbiological quality of soil and leachate J. Plant Nutr. Soil Sci. 167 704 712
Kocaer, F.O., Kemiksiz, A. & Baskaya, H.S. 2003 A study on mineralization of organic nitrogen in a sludge-amended soil Ekoloji 12 12 16 [in Turkish with English summary].
Ledeboer, F.B. & Skogley, C.R. 1973 Effects of various nitrogen sources, timing, and rates on quality and growth rate of cool-season turfgrasses Agron. J. 65 243 246
Loschinkohl, C. & Boehm, M.J. 2001 Composted biosolids incorporation improves turfgrass establishment on disturbed urban soil and reduces leaf rust severity HortScience 36 790 794
Markham, T.D. 1998 Use of composts in sand-based putting greens and their impact on turf establishment and health MS thesis, The Ohio State Univ. Columbus, OH
McLean, E.O. 1982 Soil pH and lime requirement 199 223 Page A.L., Miller R.H. & Keeney D.R. Methods of soil analysis, Part 2. Chemical and microbiological properties SSSA Book Ser. 9. SSSA and ASA Madison, WI
Moreda, J.M., Arranz, A., De Betono, S.F., Cid, A. & Arranz, J.F. 1998 Determination of PCBs and LABs in sewage sludge from a wastewater treatment plant Environ. Technol. 19 913 921
Nelson, D.W. & Sommers, L.E. 1982 Total carbon, organic carbon, and organic matter 539 579 Page A.L., Miller R.H. & Keeney D.R. Methods of soil analysis, Part 2. Chemical and microbiological properties SSSA Book Ser. 9. SSSA and ASA Madison, WI
Oral, N. & Acikgoz, E. 2001 Effects of nitrogen application timing on growth and quality of a turfgrass mixture J. Plant Nutr. 24 101 109
Pescod, M.B. 1992 Wastewater treatment and use in agriculture—FAO irrigation and drainage paper 47, T0551/E Rome, Italy.
Rhoades, J.D. 1982 Soluble salts 285 290 Page A.L., Miller R.H. & Keeney D.R. Methods of soil analysis, Part 2. Chemical and microbiological properties SSSA Book Ser. 9. SSSA and ASA Madison, WI
Schumann, G.L., Soares, H., Holden, C.M. & Switzenbaum, M.S. 1993 Relationship of traditional parameters of compost stability to turfgrass quality Environ. Technol. 14 257 263
Siddique, M.T. & Robinson, J.S. 2004 Differences in phosphorus retention and release in soils amended with animal manures and sewage sludge Soil Sci. Soc. Amer. J. 68 1421 1428
Singh, R.P. & Agrawal, M. 2007 Effects of sewage sludge amendment on heavy metal accumulation and consequent responses of Beta vulgaris plants Chemosphere 67 2229 2240
Sotirakou, E., Kladitis, G., Diamantis, N. & Grigoropoulou, H. 1999 Ammonia and phosphorus removal in municipal wastewater treatment plant with extended aeration Global Nest Intl. J. 1 47 53
Spangenberg, B.G., Fermanian, T.W. & Wehner, D.V. 1986 Evolution of liquid-applied nitrogen fertilizers on Kentucky bluegrass turf Agron. J. 78 1002 1006
Tesfamariam, E.H., Annandale, J.G. & Steyn, J.M. 2009 Exporting large volumes of municipal sewage sludge through turfgrass sod production J. Environ. Qual. 38 1320 1328
Thomas, G.W. 1982 Exchangeable cations 159 165 Page A.L., Miller R.H. & Keeney D.R. Methods of soil analysis. Part 2. Chemical and microbiological properties SSSA Book Ser. 9. SSSA and ASA Madison, WI
Topac, F.O., Baskaya, H.S. & Alkan, U. 2008 The effects of fly ash incorporation on some available nutrient contents of wastewater sludges Bioresour. Technol. 99 1057 1065
Udom, B.E., Mbagwu, J.S.C., Adesodun, J.K. & Agbim, N.N. 2004 Distributions of zinc, copper, cadmium and lead in a tropical ultisol after long-term disposal of sewage sludge Environ. Intl. 30 467 470
USEPA 2010 Environmental regulations and technology. Control of pathogens and vector attraction in sewage sludge. U.S. Environmental Protection Agency Center for Environmental Research Information Cincinnati, OH 625/R-92-013.
Withers, P.J.A., Clay, S.D. & Breeze, V.G. 2001 Phosphorus transfer in runoff following application of fertilizer, manure, and sewage sludge J. Environ. Qual. 30 180 188