**6. Types of sewage and wastewater treatments**

The accumulation of wastewater through urban wastewater treatment systems is a rising environmental problem. A crucial component of sewage management is manure sludge. Through the treatment of wastewater, sludge is created. Wastewater is made up of liquid or water-borne wastes that are separated from institutions, homes, industries, and organizations, as well as groundwater, stormwater, and surface water [11].

It is organic because it contains carbon compounds like paper, human waste, vegetable matter, and so on. It is composed of 99.9% water and 0.1% solids. In the area, there is industrial effluent in addition to sewage from the local communities. In the same manner that sewage is handled physically, chemically, and/or by microorganisms, many industrial wastes also have an organic nature. Using either physical–chemical processes or microorganisms, in order to treat sewage and wastewater, complex organic compounds must be broken down into less unstable, odorless substances. The contaminants in wastewater are removed by physical, chemical, and biological means [12].

In basic, advanced, and secondary wastewater treatment methods, sludge is produced. It is categorized as basic, advanced, and secondary sludge produced in innovative wastewater treatment, respectively. Secondary sludge is made up of biological solids as well as additional settable solids, while primary sludge is made up of settable solids transported in the untreated wastewater. Advanced wastewater can produce sludge that contains highly resilient viruses, heavy metals, nitrogen, or phosphorus.

### **6.1 Sludge disposal and treatment**


x.Final treatment (pyrolysis, wet oxidation, drying, incineration, composting, and line addition) [10].

#### **6.2 Disposal of municipal sludge**

Sewage sludge is now primarily disposed of via agricultural usage; 11% is burned, 40% is dumped, 37% of the produced sludge is used in agriculture, and 12% is used in other sectors, including forestry, silviculture, land restoration, and so on. Significant scientific interest has been produced by the most recent developments in management of sewage, including co-combustion of sewage sludge with other substances for future use as a source of energy, moist oxidation, decomposition, gasification, and combustion of sludge.

#### **6.3 Incineration technique**

The most attractive disposal technique is still incineration. In terms of procedure engineering, fuel efficiency, and plant efficiency, incineration technology has made significant progress in recent years. Advanced fluid bed incinerators are gaining popularity due to their lower capital and operating cost. Sludge volume is massively diminished; after combustion, it is only about 10% of what it was after mechanical dewatering.


### **6.4 Thermal processing**

To meet the ever-stricter regulations, sewage sludge is thermally processed, which makes use of the energy that has been stored in the sludge while also minimizing any negative environmental effects. Sludge is widely recognized for having high moisture levels. To decrease the amount of moisture, most of the energy released during thermal operations is used. Various contemporary technologies have recently been established, providing an alternate tendency to the disposal of sewage sludge, particularly with the declining availability and rising cost of land for landfilling. The primary representatives of the thermal processing are pyrolysis, gasification, moist oxidation, and combustion. These technologies can all be categorized under the heading of thermal exploitation of sewage sludge [10].

#### **6.5 Combustion**

For the warm air processing of sewage, several techniques have been developed and are available on the market. The most well-established method involves the onetrack- and co-combustion of sewage sludge, with mono-burning (combustion) being considerably more prevalent. For the warm air processing of sewage sludge, various fluidized bed and hearth technologies have been developed. The extremely wellrecognized ones include the one-track- and co-burning of sewage sludge, with being significantly more common. As opposed to single hearth furnaces, multiple hearth

*Remediation and Management of Sewage Sludge DOI: http://dx.doi.org/10.5772/intechopen.109408*

furnaces typically consume mechanically wet (dewatered) sludge. Whereas, fluidized bed furnaces may burn sludge with a dry matter composition of 41–65 wt% that is both wet and semi-dried. The release and combustion of volatiles, drying of sludge, and the burning of the extreme residue content left over as char are the dominant factors that might possibly alter the general combustion procedure of sewage sludge. According to the makeup of sewage sludge, burning of the sludge might be viewed as a cause of possible contaminants; thus, caution must be used while disposing of it.

