When WWTPs focus on reducing COD, ammonia, phosphor, industrial civilization is becoming a stumbling block to ecological civilization

I. Starting with "Victory in Metrics"

For the past three decades, we have hung giant banners proclaiming "COD Removal" at the entrance of wastewater treatment plants, as if a continuous decline in chemical oxygen demand would automatically restore rivers to clarity and bring about the ecological world we desire. Yet behind these banners, an invisible dark line is extending underground—soil organic matter is decaying at an alarming rate. In many regions, it has already dropped to less than 0.3%. How much of China’s land today still supports earthworms? On land where even earthworms cannot survive, isn’t it somewhat cruel to keep talking about biodiversity and green mountains? Why are affluent diseases like diabetes soaring in China today? Denying the connection between these trends and ecology seems utterly indefensible.

II. What "Environmental Protection" Has Intercepted Is More Than Just "Pollution"

1. Livestock manure, human excrement, distillery waste, food processing wastewater—in traditional agricultural cycles, these were known as "black milk" that nourished the soil. Today, however, they are labeled as "high-COD" waste and confined to anaerobic tanks, incinerators, and aeration basins. Amid cheers for "meeting discharge standards," they are transformed into carbon dioxide, sludge, and methane—which ultimately also becomes CO₂.

2. We may be winning the battle for water quality metrics, but we are severing the soil’s "food chain." For every ton of high-COD wastewater treated, dozens or even hundreds of kilograms of organic carbon are diverted from returning to the earth and instead released into the atmosphere. The problem is: while everyone knows greenhouse gases in the atmosphere are excessive, very few are aware of the critically low levels of soil organic matter. Did the widespread and persistent high temperatures across China and Europe in 2025 serve as a wake-up call? It’s time we face the truth. As we relentlessly extract from the land—even burning crop residues for power generation—an ecological disaster is quietly brewing.

We must combat pollution—the achievements of the past three decades in environmental protection are evident. But we must also protect ecosystems. We cannot allow temperatures to rise year after year in the next decade, turning us all into "heat-enduring creatures." Pollution control and ecological preservation need not be contradictory. With today’s advanced technology, eliminating COD is not the only way; we can transform it. Environmental protection doesn’t always require removing nitrogen and phosphorus; we can also recover them. What our society lacks is ecological awareness, policy incentives with depth, and mechanisms that allow innovative technologies to thrive.

III. The "Four Blows" of Soil Organic Matter Decline

Healthy soil hosts a microbial community whose interactions and symbiosis sustain soil productivity. When organic matter plunges to levels that can no longer support this community, the very essence of "soil" ceases to exist.

1. Sharp decline in nitrogen-fixing bacteria—Chemical fertilizers have shifted from "supplements" to "life-sustaining drugs," with usage rising yearly. Nitrogen oxides have now become a major contributor to smog.

2. Drastic reduction in actinomycetes and fungi—These once served as "natural antibiotic" factories for plants. In their absence, pesticides have taken over.

3. Soil degradation into "dirt mines"—Porosity and aggregate structure collapse. Roots struggle to survive as if in concrete, and "high yields" rely increasingly on hormones and technological interventions.

4. Sharp decline in native vitamins and growth hormones—Crops widespread in "sub-health"状态 mean humans must rely on dietary supplements to compensate for micronutrients that should come from food. Healthcare funds face additional strain—why else would insurance premiums keep rising every year?

IV. Why Does "Environmental Protection" Become an Ecological Killer?

We treat COD as an ultimate evil, forgetting that it is also "food" for soil microbes.

• Positive: COD reduction = decrease in water pollutants.• Negative: COD reduction = carbon released into the atmosphere = soil starvation.

When "eliminating COD" becomes the sole KPI, we are applying an engineer’s mindset to ecological subtraction: as long as the metrics look good, even at the cost of wiping out soil microbial life.

V. Soil Has "Self-Healing Power," But We Have "Amputated" It

Healthy soil hosts the planet’s largest "underground cities":• One gram of fertile soil contains microbes comparable to the global human population.• They decompose and transform organic matter, fix nitrogen, suppress pathogens, and synthesize vitamins.• They can even degrade pesticides and immobilize heavy metals.

Yet, urbanization and industrialization have "intercepted" organic matter in pipelines and smokestacks. We have dismantled this city’s "food supply chain" with our own hands.

VI. Our Appeal: Let Some COD Go Home!

1. Categorized Return: After pathogen inactivation and heavy metal remediation, organic waste streams (e.g., livestock biogas slurry, food fermentation wastewater) should be reintegrated into farmland instead of being incinerated or mineralized.

2. Carbon Ticket Trading: Incorporate "soil carbon enhancement" into carbon markets, allowing farmers and stakeholders to profit from "burying carbon in the ground" rather than relying solely on crop sales.

3. Promote Resource Utilization: Encourage the industrial recycling of organic waste into microbial agents, plant nutrients, and liquid fertilizers to partially replace chemical fertilizers and pesticides. Environmental regulations should not become barriers to ecological cycles.

4. Public Education: COD is not a demon—it is a misplaced resource. Organic matter is not dirty water—it is utilizable nutrition. True environmental protection means enabling carbon to cycle among the atmosphere, plants, soil, and microbes, sustaining ecological systems rather than merely converting it into CO₂ and releasing it into the sky. Otherwise, one day, we and our descendants may be the ones "craning our necks to sing toward the sky." As Academician Peng Yongzhen once said: If we don’t return organic matter from sewage sludge to the fields, all we’re left with is returning chemical fertilizers. Can elites in environmental and ecological industries courageously tell society that by mineralizing all organic matter and immobilizing even the last minerals—diverting them from soil return—we have at least partially broken the ecological cycle of organic and mineral matter?

There is still a long way to go from industrial civilization to ecological civilization

VII. Conclusion: Give "Ecology" Back to Environmental Protection

Stop letting the "COD basket" carry away the soil’s last food reserves.Allow organic matter from certain industries to return to the earth. Let nitrogen-fixing bacteria resume work, let actinomycetes sing again, let plant roots breathe deeply in soft soil.

Environmental protection should not be merely an engineer’s metrics game.Ecology is the lowest-cost "insurance" we can leave for the next generation.

Today, if you also agree that we should "let COD go home," please share this article. Let policymakers, entrepreneurs, farmers, and consumers hear this—Our soil is starving.

*Ref: Ecological little snail