Hazard assessment of the digested sludge composting plant : a case study of Bangkok Metropolitan Administration in Thailand | |
| Author | Nittaya Sruntammagun |
| Call Number | AIT Thesis no.EV-06-25 |
| Subject(s) | Refuse and refuse disposal--Thailand--Bangkok Sewage sludge--Thailand--Bangkok |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | Large cities have a rapidly increasing population and relatively small land areas in terms of density as well as green areas. One from the effects of the growing population is a significant increased wastewater and sewage sludge generation as a result large volumes of treated residuals from wastewater treatment were produced. Therefore, sludge is applied to land that provides a major source of plant macro-nutrients such as nitrogen, phosphorus and potassium. Moreover, it provides micro-nutrients such as copper, iron and zinc, and organic matter as a soil conditioner. In addition to the essential nutrients, sludge also contains heavy metals and pathogen which can impact to environment and human health if such applied sludge is not treated and managed properly for example in Bangkok. After stabilizing the sludge by anaerobic digestion process, the digested sludge (DiS) should consist of (1) reduced pathogens, (2) eliminated offensive odors, and (3) inhibited, reduced, or eliminated potential for putrefaction. Unfortunately, the DiS of BMA contains some metals and pathogen above the limiting standards/guidelines. Thus, aerobic DiS cocomposting process is proposed as a good option to reduce pathogens and metals to meet organic fertilizer standards/guidelines. The objective of this study is to determine the current DiS that managed by aerobic composing process and construction site. The investigation has been conducted at the selected area - Nongkheam district. Data collection, field survey, and interviews were also held to get information. The overall impact analysis of the hazard assessment has been modified based on the conceptual design of the proposed central digested sludge composting plant (CDSCP) to protect environment and human health if the plant operates. The result showed that the composition of DiS consists of some metals (Cu) and pathogens above the standard/guideline set by countries. So aerobic DiS co-composting process was proposed as it reduces further pathogens at high temperature process and metals can be diluted by addition of clean organic matter (OM) such as garden waste from public green area in Bangkok. The recommendation of DiS compost is then suitable to use for public green areas because Bangkok still needs more compost and less supply. The estimation was calculated to follow green area per capita of the Master Plan for BMA's Green Areas which grow nonedible plants or trees. For the CDSCP, hazard assessments are caused by natural and human hazard should be considered into two parts: processing and location of site. Cause from natural hazards such as wind (gases, bio-aerosols, odor and dust), rain (leachate accumulation and flooding), and land subsidence (flooding). And human hazard impacts human health by leakage, spillage, and accidents that worker may be impacted by contacting. Both hazard types can be reduced or minimized and controlled by hazard management such as the modification of conceptual design (close system for aerobic DiS co-composting process; collecting gases/bio-aerosols/odor/dust by bag filters before emission; providing drainage system to collect the leachate; making a concrete fence for the diversion or change wind direction to the buffer zone are occupied by perennials plants or trees, and dust collection including substantial noise reduction). The service and maintenance must be followed using the operation manual (which can reduce impact from processes such as leakage, spill and accident), which is recommended to be included in the emergency plan for all types of accidents.Large cities have a rapidly increasing population and relatively small land areas in terms of density as well as green areas. One from the effects of the growing population is a significant increased wastewater and sewage sludge generation as a result large volumes of treated residuals from wastewater treatment were produced. Therefore, sludge is applied to land that provides a major source of plant macro-nutrients such as nitrogen, phosphorus and potassium. Moreover, it provides micro-nutrients such as copper, iron and zinc, and organic matter as a soil conditioner. In addition to the essential nutrients, sludge also contains heavy metals and pathogen which can impact to environment and human health if such applied sludge is not treated and managed properly for example in Bangkok. After stabilizing the sludge by anaerobic digestion process, the digested sludge (DiS) should consist of (1) reduced pathogens, (2) eliminated offensive odors, and (3) inhibited, reduced, or eliminated potential for putrefaction. Unfortunately, the DiS of BMA contains some metals and pathogen above the limiting standards/guidelines. Thus, aerobic DiS cocomposting process is proposed as a good option to reduce pathogens and metals to meet organic fertilizer standards/guidelines. The objective of this study is to determine the current DiS that managed by aerobic composing process and construction site. The investigation has been conducted at the selected area - Nongkheam district. Data collection, field survey, and interviews were also held to get information. The overall impact analysis of the hazard assessment has been modified based on the conceptual design of the proposed central digested sludge composting plant (CDSCP) to protect environment and human health if the plant operates. The result showed that the composition of DiS consists of some metals (Cu) and pathogens above the standard/guideline set by countries. So aerobic DiS co-composting process was proposed as it reduces further pathogens at high temperature process and metals can be diluted by addition of clean organic matter (OM) such as garden waste from public green area in Bangkok. The recommendation of DiS compost is then suitable to use for public green areas because Bangkok still needs more compost and less supply. The estimation was calculated to follow green area per capita of the Master Plan for BMA's Green Areas which grow nonedible plants or trees. For the CDSCP, hazard assessments are caused by natural and human hazard should be considered into two parts: processing and location of site. Cause from natural hazards such as wind (gases, bio-aerosols, odor and dust), rain (leachate accumulation and flooding), and land subsidence (flooding). And human hazard impacts human health by leakage, spillage, and accidents that worker may be impacted by contacting. Both hazard types can be reduced or minimized and controlled by hazard management such as the modification of conceptual design (close system for aerobic DiS co-composting process; collecting gases/bio-aerosols/odor/dust by bag filters before emission; providing drainage system to collect the leachate; making a concrete fence for the diversion or change wind direction to the buffer zone are occupied by perennials plants or trees, and dust collection including substantial noise reduction). The service and maintenance must be followed using the operation manual (which can reduce impact from processes such as leakage, spill and accident), which is recommended to be included in the emergency plan for all types of accidents |
| Year | 2006 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering and Management (EV) |
| Chairperson(s) | Preeda Parkpian; |
| Examination Committee(s) | Aramaki, Toshiya ;Katerachada Klankrong; |
| Scholarship Donor(s) | Future Engineering Consultants Co., Ltd. ; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2006 |