Water resources are one of the important natural resources on which people rely for survival. In a modern environment, water pollution caused by daily life and production not only affects the rational utilization of water resources but also has a significant impact on the local ecological environment, potentially threatening human health. The treatment of black and odorous water pollution is a task that China currently attaches great importance to. To do a good job in pollution control, it is necessary to understand the current pollution status, identify pollution problems, and finally formulate targeted treatment methods to ensure the effectiveness of black and odorous water pollution control.

Production and daily life inevitably lead to issues regarding the utilization and discharge of water resources. With domestic economic development and the gradual increase in population in certain areas, the discharge of domestic and industrial wastewater has become larger, and some sewage is discharged basically without any treatment. This directly leads to the pollution of local water resources and the ecological environment, resulting in black and odorous water conditions. Although China currently advocates for ecological protection and pollution control, small and medium-sized rivers in some areas remain in a black and odorous state year-round, affecting the regional image and the health of local populations.

I. Current Status of Black and Odorous Water Pollution

(1) Incomplete Ecosystem

Analysis of some black and odorous water bodies shows that various aquatic organisms originally in the river channels have disappeared, failing to form a complete biological community. Ultimately, the overall ecosystem of the water body collapses, with low transparency, high turbidity, poor fluidity, and a basic loss of self-purification capacity. It cannot assimilate pollutants entering the river, so the black and odorous problem remains unresolved.

(2) Complex Pollution Sources

Taking urban river channels as an example, some have issues such as mixed rainwater and sewage pipes, and lack of long-term sediment cleaning. Inadequate sewage interception and pipe networking lead to discharge issues and water pollution. Furthermore, in some suburbs and "villages within cities," pollution sources are more complex. For instance, in livestock and poultry farming, some farmers do not standardly treat pollutants such as manure, discharging them directly into water channels.

(3) Direct Discharge of Domestic and Industrial Sewage

Factories, mines, and domestic wastewater in some areas are discharged directly into rivers, keeping the pollution load high. Over long periods, pollutants accumulate in the water, and river sediments become rich in nutrients, worsening the black and odorous condition.

II. Methods for Treating Black and Odorous Water Pollution

(1) Internal Source Control and External Source Control

Internal source control involves using sediment dredging to manage internal pollution, which can improve water quality in a short time, enhance self-purification and flood discharge functions, and effectively alleviate pollution. However, dredging disturbances can release more pollutants into the water, potentially harming the ecological balance. Moreover, if dredged sediment is not properly treated, secondary pollution may occur. Therefore, this is not a long-term treatment method. External source control refers to non-point source control and sewage interception. Controlling the source—treating before discharging—is essential. For cities, source control involves sponge city technologies and ecological revetment technologies. Effective cleaning of garbage around water bodies is also a vital way to control non-point source pollution.

(2) Physical and Chemical Methods

Common physical methods include artificial aeration and water diversion for flushing/dilution. Aeration provides oxygen to restore dissolved oxygen in bottom layers, reducing the concentration of iron, hydrogen sulfide, or ammonia nitrogen, and strengthening self-purification. Water diversion speeds up water exchange, shortens pollutant residence time, and lowers pollutant concentrations. Chemical methods often involve chemical flocculation, such as adding calcium or iron salts to turn dissolved phosphates into insoluble solids that settle in the sediment. While efficient, chemical methods are costly and may cause secondary pollution if handled improperly.

(3) Biological and Ecological Restoration Methods

Biofilm technology uses natural or synthetic materials (like pebbles or fibers) as carriers for a special biofilm that provides a large surface area for microorganisms to degrade pollutants. Another method is the introduction of specific microorganisms to increase the concentration of effective microbes, accelerating the degradation of organic matter. Additionally, introducing aquatic animals like omnivorous or carnivorous fish and shellfish (mussels, snails) can regulate the biological ratio and density, stabilizing the ecological purification system and improving water quality.

YexSensor Intelligent Monitoring Matrix for Water Restoration

Frequently Asked Questions (FAQ)

Q1: Why is the optical DO sensor superior to traditional electrochemical sensors in black and odorous water?
   A: Black and odorous water often contains hydrogen sulfide (H2S), which poisons electrochemical sensors. The optical principle (YEX-RDO-206) does not consume oxygen and is immune to H2S, drastically reducing maintenance frequency.

Q2: How can integrators monitor secondary pollution during sediment dredging?
   A: We recommend deploying Turbidity and ORP units 50 meters downstream. A sudden drop in ORP indicates the release of reductive substances from sediment, triggering real-time alerts for construction adjustment.

Q3: Does the YEX-NHN-206 Ammonia Nitrogen sensor require a separate transmitter?
   A: No. It is a fully digital sensor with an integrated transmitter. The RS485 signal can be read directly by any PLC or IoT gateway, simplifying system architecture.

Q4: For rivers with extremely slow flow, which monitoring indicator is most valuable?
   A: ORP (Oxidation-Reduction Potential) is the leading indicator. ORP < -100mV usually means the water is in a deep anaerobic state, and odors are imminent.

Q5: How can system integrators solve power supply issues for distributed monitoring?
   A: YexSensor digital sensors have extremely low power consumption (<0.2W). Integrators can use a "Solar + Lithium Battery + NB-IoT/4G" unit for long-term independent operation.

Q6: How to handle high oil and grease content in black water monitoring?
   A: We suggest using sensors with automatic wipers and applying a Teflon coating to the probe body to minimize oil adhesion and biological fouling.

Q7: Is UV Spectrometry COD measurement accurate in turbid water?
   A: The YEX-COD-206 utilizes dual-wavelength (254nm and 365nm) compensation technology to automatically subtract turbidity interference, ensuring high accuracy in field conditions.

Q8: Can YexSensor provide protocol maps for SCADA integration?
   A: Yes. We provide comprehensive Modbus register maps and technical documentation to ensure seamless communication with all industrial SCADA and Cloud platforms.

Conclusion: Digital Perception Empowering Ecological Balance

The appearance of black and odorous water is an external manifestation of serious pollution in the natural environment, generally caused by the random discharge of domestic and industrial sewage, leading to a negative impact on the ecological environment. To solve this problem, various treatment methods are available. We should refer to the pollution status and conditions of the water body to choose suitable treatment methods, ensure the treatment effect, and maintain ecological balance.

By combining scientific restoration methods with YexSensor's high-precision digital sensing matrix, system integrators can deliver long-term, stable, and data-driven water treatment solutions.

Technical Support:
       For detailed sensor specifications, MODBUS manuals, or wholesale pricing for environmental engineering projects, please contact the YexSensor engineering team.