Most engineers know that certain compounds such as PCBs, Dioxin, or DDT are not amenable to biological detoxification. Between non-biodegradable and readily-degradable compounds are a large spectrum of resistant or slowly-biodegradable compounds. When you mix multiple compounds on a single site, individual degradation rates are often different than single compound studies done in a lab. So what should be considered when evaluating compounds/sites for biological treatment:
Number 1 is based on the hazardous material itself - some compounds are not amenable to biological degradation. The next 4 questions cover environmental factors that can be altered to promote biological treatment or simplified - you must make the conditions favorable to microbial growth. Finally, Number 6 covers the existing microbial population. If the needed microbes are not present or in insufficient numbers, detoxification will not occur. This is where bioaugmentation with required cultures initiates biological treatment.
- Does the molecular structure prevent enzymes from acting - (example is the chlorine on DDT or PCBS)
- Is the compound accessible to the microbes or enzymes (physical availability)
- Some essential factor (nutrient or vitamin) for microbes is absent
- Surrounding environment is toxic or inhibitory (heavy metals, temperature, salinity)
- Requisite enzymes are inactivated (pH, temperature, metals)
- Current microbial community does not contain organisms with correct metabolic capapbilities
Number 1 is based on the hazardous material itself - some compounds are not amenable to biological degradation. The next 4 questions cover environmental factors that can be altered to promote biological treatment or simplified - you must make the conditions favorable to microbial growth. Finally, Number 6 covers the existing microbial population. If the needed microbes are not present or in insufficient numbers, detoxification will not occur. This is where bioaugmentation with required cultures initiates biological treatment.
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