MBC Mixed Filler Retrofit Solution for Wastewater Plant Upgrade

Eight Chinese ministries including the Ministry of Ecology and Environment jointly issued the Notice on Further Strengthening Industrial Wastewater Pollution Risk Prevention and Safeguarding Agricultural Irrigation Water Safety (Document No. Huan-Ban-Shui-Ti [2026] No. 13), reinforcing industrial wastewater pollution risk prevention and agricultural irrigation water safety.

The document explicitly calls for improving wastewater collection and treatment efficiency in industrial parks, accelerating the construction and renovation of centralized wastewater treatment facilities near agricultural areas, and achieving full collection, full treatment, and stable compliance discharge. It also imposes stricter controls on characteristic pollutants from industrial enterprises and park-level discharges.

For wastewater treatment facilities that have been operating for years, this sends a clear signal: treatment systems must not only be built, but also collect comprehensively, treat stably, and comply long-term. For plants with limited tank volume facing upgrade pressure, how to improve biological treatment capacity without adding new tank volume has become a critical question.

01 The Pressure Extends Beyond Industrial Parks

Industrial park wastewater and livestock farming effluent differ in water quality characteristics, but share a common problem: existing treatment facilities, after years of operation, often lack sufficient process margin to handle stricter regulatory requirements and increasingly complex influent fluctuations.

For industrial park wastewater plants, the key concerns are water quality fluctuations from multiple industrial streams, characteristic pollutants, and biological system stability. For livestock wastewater stations, the focus shifts to organic load, ammonia nitrogen, total nitrogen, suspended solids (SS), and seasonal variations.

Livestock farms typically operate their own wastewater stations with large flow variations tied to breeding cycles, high ammonia nitrogen, total nitrogen, organic matter, fats, and SS. Industrial park plants face multiple mixed influent streams, complex characteristic pollutants, and frequent shock loads. These older stations were designed with limited flow and quality margins; now they must meet stricter discharge standards, and the original activated sludge process often cannot keep up.

For new industrial enterprises and parks, the document strengthens spatial layout, environmental access, and pollution risk prevention requirements. For existing treatment facilities, it explicitly calls for accelerating centralized wastewater treatment facility construction and renovation. For plants with limited tank volume and upgrade demands, in-situ retrofit deserves close attention.

02 Three Key Weaknesses to Identify Before Retrofit

Insufficient biomass and operating margin in aging activated sludge systems. When influent flow and quality fluctuate significantly, inadequate SRT, MLSS, aeration capacity, and biochemical tank volume can lead to declining nitrification, deteriorating sludge characteristics, and unstable effluent ammonia and total nitrogen.

Poor low-temperature nitrogen removal. As water temperature drops in winter, nitrification and denitrification rates decrease markedly. Many stations experience prolonged instability in total nitrogen and ammonia nitrogen during cold seasons.

Insufficient original biochemical tank design margin. Older stations were designed with tank volume and HRT based on historical standards. Upgrading to handle higher shock loads requires solutions within the existing tank footprint, as there is no available land for expansion.

03 Why MBC Mixed Filler Fits In-Situ Retrofit

Where expansion is not possible and prolonged shutdown is not an option, MBC mixed filler technology offers several well-matched advantages.

• In-situ retrofit, no expansion required. Adding suspended carriers into existing biochemical tanks increases effective biomass per unit volume without new tank construction, providing an in-situ upgrade pathway for stations with insufficient biological capacity.
• Higher biomass per unit volume, stronger shock load resistance. Suspended carriers provide additional biofilm attachment surface, allowing the system to maintain a certain suspended sludge concentration while increasing attached biomass. This raises biomass carrying capacity per unit tank volume and enhances adaptability to load fluctuations.
• Stable low-temperature performance. Low temperatures affect both nitrifying and denitrifying microorganisms. MBBR carriers maintain high biomass through attached biofilm, providing a more stable attachment environment for slow-growing nitrifiers under low-temperature and load fluctuation conditions, thereby improving biomass retention.

04 MBC Mixed Filler Handles Complex Influent More Stably

Different types of biofilm carriers vary in structure, specific surface area, pore characteristics, and biofilm attachment mode. For stations with complex influent quality and large pollutant load fluctuations, different carrier types can be combined based on pollutant removal targets and tank section operating conditions.

MBC mixed filler combines conventional suspended carriers with high-performance biofilm sheet carriers at a specific ratio: conventional carriers carry the main biomass, while biofilm sheet carriers provide low-shear, high-oxygen-transfer attachment space for specialized functional bacteria. Working together, they can simultaneously support nitrification and denitrification within the same tank, addressing total nitrogen compliance pressure. This approach is particularly effective for complex influent such as livestock wastewater and mixed industrial park wastewater.

05 The Smallboss Approach Verify Site Conditions First

For industrial park MBC mixed filler retrofit projects, we do not simply quote a dosage. Tongxiang Smallboss Plastic Products Co., Ltd. first works with the site team to verify influent sources, fluctuation ranges, existing tank dimensions, effluent standards, and retrofit window, then outputs carrier selection, ratio, and dosing plans.

When ammonia nitrogen is high, key parameters to verify include nitrification load, DO, alkalinity, temperature, and effective system biomass; nitrification carrier demand is then determined based on actual load. When total nitrogen pressure is significant, further analysis of carbon source, anoxic conditions, internal recirculation, and denitrification biomass is needed before determining carrier type, placement, and dosing ratio.

The joint issuance by eight ministries indicates that industrial and livestock wastewater risks near agricultural areas have been elevated to higher priority. For the wastewater treatment industry, this means stricter approvals for new projects and further release of in-situ retrofit demand for existing stations. Retrofit is not about replacing equipment; it is about solving the core weaknesses of old stations within limited space: shock load resistance, low-temperature nitrogen removal, and insufficient tank volume.

For Tongxiang Smallboss, MBC mixed filler is one part of the investment. The real value we bring is helping sites accurately characterize complex influent, precisely calculate filler ratios, and stabilize biofilm formation and system operation.