English Translation From completion of construction to stable operation, the anaerobic biological treatment system requires rigorous commissioning and start-up, meticulous daily management, and strict safety protection. Improper operation and management will not only impair treatment efficiency but may even lead to system collapse or safety accidents. This paper comprehensively summarizes the key points for operation and management of anaerobic equipment from three aspects: equipment start-up, imbalance diagnosis, and safety requirements. I. Start-up of Anaerobic Equipment Before putting anaerobic equipment into formal operation, sludge cultivation and domestication must be carried out. The start-up phase is critical to the success of subsequent system operation. 1. Sources of Inoculated Sludge The selection of anaerobic activated sludge directly affects the start-up speed and effect, with priority given as follows: 1. Sludge from in-service anaerobic treatment structures (optimal choice) 2. Anaerobic digested sludge of similar feedstock (ideal option) 3. Bottom sludge from rivers, lakes and swamps 4. Anaerobic habitat sludge from sewers and sewage accumulated putrid areas 2. Three Core Control Points for Start-up Control Point 1: TemperatureControl the heating rate at 1℃ per hour, and maintain a constant temperature once the target temperature is reached. Rapid temperature rise must be avoided to prevent thermal shock to microorganisms.Control Point 2: pH ValueKeep the pH value within the range of 6.8～7.8. Frequently monitor pH changes in the initial start-up stage to timely address the risk of acidification.Control Point 3: Organic LoadingOrganic loading is often a key factor determining start-up success. The initial organic loading varies according to process type, wastewater characteristics, temperature and properties of inoculated sludge. It shall be increased gradually according to actual conditions, and eagerness for quick results must be avoided. II. Imbalance Phenomenon and Its Causes Maintaining the balance of anaerobic digestion is the core of operation and management. The anaerobic digestion process is prone to acidification — a mismatch between acid production and acid consumption, which is defined as imbalance. Five Early Warning Signs When anaerobic digestion falls into imbalance, the system presents the following symptoms in sequence (ranked by sensitivity): 1. Increased concentration of volatile organic acids — the earliest and most effective monitoring parameter 2. Reduced methane content in biogas 3. Decline in pH value of digestive liquid 4. Decreased biogas production 5. Lower organic matter removal efficiency Monitoring Recommendation The rise in volatile organic acid concentration is the earliest indicator of imbalance and the most valuable monitoring parameter, enabling early detection of imbalance. Other symptoms are less sensitive due to hysteresis or non-specificity. Common Causes of Imbalance Anaerobic digestion imbalance stems from multiple factors requiring targeted investigation: 表格 Category Specific Manifestation Loading Factor Excessively high organic loading pH Factor Excessively low or high inlet water pH Buffering Capacity Low alkalinity and poor buffering capacity Toxicity Factor Inhibition by toxic substances Temperature Factor Sharp fluctuation of reaction temperature Oxidation Factor Presence of dissolved oxygen and oxidants in the tank Countermeasures for Imbalance Emergency Treatment Once an imbalance is detected, immediate control and correction are required to prevent further deterioration and digestion stagnation.Lime milk may be temporarily dosed to neutralize accumulated acid. However, note that excessive lime milk will kill microorganisms and aggravate the problem instead. Fundamental Solutions The fundamental solution to imbalance is to identify the root cause and adopt targeted corrective measures — reducing loading, adjusting pH, removing toxic substances, or stabilizing temperature, as appropriate. III. Safety Requirements in Operation and Management Safety is the top priority in the operation and management of anaerobic equipment. The biogas system involves flammable, explosive, toxic and harmful gases, which must be managed strictly. 1. Explosion Risk of Biogas Methane in biogas is lighter than air and highly flammable. An explosion will be triggered by open flames when methane accounts for 5%～15% of air volume. 2. Sealing Requirements Digesters, gas storage tanks, biogas pipelines and all auxiliary facilities of the biogas system shall be completely sealed to prevent biogas leakage and air ingress into the biogas system.Open flames and electrical sparks are strictly prohibited in the surrounding area, and all electrical equipment shall meet explosion-proof requirements. 3. Protection Against Toxic and Harmful Gases 表格 Gas Composition Characteristics Key Protection Points Hydrogen Sulfide (H₂S) Toxic; trace amounts are detectable; heavier than air Prevent accumulation in low-lying areas Carbon Dioxide (CO₂) Non-toxic but asphyxiating; heavier than air Prevent accumulation in low-lying areas 4. Safety Regulations for Tank Entry Mandatory Safety Rule: Before entering the digester for discharging or maintenance, the internal digestive gas must be completely replaced with fresh air. This is an inviolable safety red line. Series Summary of Anaerobic Biological Process Through systematic elaboration in five articles, we have gained a comprehensive understanding of anaerobic biological treatment technology from basic principles, influencing factors, process equipment and kinetics to operation and management: 1. Basic Principle: Organic matter is anaerobically degraded through three collaborative stages: hydrolysis and acidification → hydrogen-producing and acetogenesis → methanogenesis. 2. Influencing Factors: Eight key parameters including temperature, pH, redox potential, organic loading, sludge condition, stirring, nutrient ratio and toxic substances require precise control. 3. Process Equipment: Seven mainstream processes with distinct characteristics, including conventional digesters, UASB, anaerobic filters and fluidized beds, applicable to diverse scenarios. 4. Kinetics: Reveals the quantitative relationship between microbial growth and substrate degradation from a mathematical perspective to guide engineering design. 5. Operation and Management: Scientific start-up, timely imbalance diagnosis and strict compliance with safety bottom lines guarantee long-term stable operation of the system. With unique advantages such as low energy consumption, high loading capacity and biogas energy recovery, anaerobic biological treatment technology will continue to play an irreplaceable role in wastewater treatment, especially for high-concentration organic wastewater.
