Essay --

As a basic knowledge, solids that caught or settled within the treatment process can be reused or disposed in an environmental friendly way. Rule such as safety wastewater treatment has to be implemented to the wastewater solids is regulated by several federal laws, including the Clean Water Act (CWA), Resource Conservation and Recovery Act (RCRA), and so on. Recently, most of the biosolids produced is either reused as a soil conditioner, fertilizer or disposed by incinerated and land filled. As a matter of fact, biosolids have to be stabilized first to control odours and reduces the microbial population by thickening, composting, heat treatments, drying, conditioning and dewatering. Lime, ferric chloride, alum or polymers are used to condition the biosolids as to produce larger particles for easier removal and prepared for further dewatering. Dewatering processes include vacuum filtration, pressure filtration, and centrifuges. The process of decomposing volatile material naturally is known as digestion (a type of stabilization method), manages to reduce the odour, yields biologically stable end product (aerobic digestion) and produces methane gas (anaerobic digestion). After stabilization, the biosolids are either introduced to land application or disposed after incineration. Biosolids can act as fertilizer and soil conditioner, as they contain organic matters (nutrients) for the plants and manage to amend poor soil structure land due to practices such as construction activities. Moreover, biosolids can be incinerated (burned) to ashes, having high fuel value as a result. Pressure filtration dewatering equipment is basically used or refuse-derived fuel is added to obtain biosolids which are sufficiently dry to take advantage of... ... manage to direct the wastewater reclamation plants to meet the quality requirements of intended reuse applications. (National Academies, 2012) Disposal of municipal wastewater have been distributed into two categories, which are those that discharge directly to surface water and those that discharge to land. Surface water discharge economically has been preferred because it provides rapid mixing of effluent with surface water, and is the least expensive discharge option. Nonetheless, indirect discharge to groundwater or hyporheic water may be more environmentally beneficial if planned, installed, and operated correctly. There are also many methods for land discharge, for example, discharge into two to three feet wide and two feet deep of ground trench and added in successive layers until the lagoons is completely filled. (Department of Environmental Quality, 2007)