For Domestic Wastewater Treatment, Finding Optimum Conditions by Particle Swarm Optimization and Experimental Design

Development of industry and rising of population in urban areas increase the amount of domestic wastewater day by day. Releasing of untreated waste water pollute fresh water sources. Therefore, treatment of wastewater is important to meet the growing freshwater demand.  

Inappropriate usage of water can only be decreased with developing water techniques (JSackson et al., 2001; Bixio et al., 2006; Karr et al., 1991; Saurer et al., 2008; Shiva et al., 2002, S.Sarıoglu 2005). One of the water controlling policies is separating into gray water and black water. In addition, gray water is treated easier instead of fixed wastewater (Mülleger et al., 2003; Scheumann et al., 2007 S.Sarıoglu 2005).  

Gray water comes from bathing, wash basins or sinks, washing machines, dish washing, kitchen etc. Gray water doesn‟t include urine and faces, so it contains less organic matter and nutrients than black water (Sarıoglu 2005; Schafer et al., 2006; Ramon et al., Eriksson et al., 2002; Jefferson et al., 2004; March et al., 2004).  

Gray water can be separated into low-load and high-load. High-load wastewater has more concentration of detergent than the other one. Kitchen, washing machine and dishwashing machine waters are high-load type. On the other hand, low-load wastewater which comes from bathing, wash basins or sinks wastewater has low concentration of detergent.  

Gray water has less polluted, so treatment of it is more easy and economic than black one (Sarıoglu, 2011; Ramon et al., 2004; Nolde, 1999; Eriksson ve ark., 2002; Sandec, 2006). Treated gray water can be reused for toilet flushing, irrigation of lawns, parks, washing of vehicles, fire protection and concrete production water etc(Anderson et al., 2003; Angelakis et. al.2001; Friedler et al., 2001, Sarıoglu, 2011).  

Mixing of black and gray wastewater can be treated with difficulty and not a good way of urban wastewater usage. Figure 1. gives conventional and alternative methods for urban water usage and treatment. In conventional one, black wastewater and gray wastewater are mixed. But, in alternative method, gray waste water is treated easy and then reused (March et al., 2004). 

In this study, gray wastewater coming from washing machines was treated with coagulation method by using Alum, FeCl3 and FeSO4 coagulant and found proper concentration of them for treatment with statistical optimization approach.