Sanitation Upgrading Technology for Dry Toilets

    This process is a harmless treatment and resource utilization technology, consisting of an odor-proof squat pan/toilet and a three-compartment septic tank with a 2:8 volume ratio made of PE material. The squat pan has a 160 mm diameter outlet at the bottom, which is directly connected to the first compartment of the septic tank. The joint between the squat pan and the septic tank must be sealed to prevent biogas leakage, eliminating the need for an additional exhaust pipe for the septic tank. The three compartments of the septic tank serve distinct purposes: the first is a fecal waste collection and anaerobic decomposition tank, the second is an anaerobic fermentation tank (sanitization tank), and the third is a resource utilization tank (organic liquid fertilizer storage tank). 

    In the first compartment, our company's bio-bacterial strains and special biofilm-forming media are added to allow the strains to form a biofilm, preventing loss of the strains. Our "Bio-Bacterial Strain DGHBJZ-001" has official test reports, proving it is non-toxic, harmless, and free of heavy metals. Its biological reaction process can adapt to temperatures ranging from -40°C to 40°C. The bio-bacterial strains can self-dormant, self-activate, and self-reproduce, requiring no secondary maintenance, and exhibit excellent deodorizing effects.

Working Principles of Each Compartment

1. First Compartment: The bio-bacterial strains convert macromolecular organic matter into small-molecule forms, promoting anaerobic fermentation, inhibiting the growth of harmful bacteria, and altering their genes to convert them into beneficial ones. 

2. Second Compartment: The sewage overflows into this anaerobic fermentation tank for further harmless treatment. This process effectively inhibits the growth of coliforms and parasite eggs, decomposing pollutants into components like carbon dioxide and water, meeting national sanitary standards for harmless treatment.

3. Third Compartment: The treated sewage finally overflows into this resource utilization tank, where it is stored as organic liquid fertilizer for farmers to use in their private farmland or vegetable plots. Soil irrigated with the organic liquid fertilizer treated with our bio-bacterial strains will not experience compaction. 

    This process delivers simple construction, zero energy consumption, maintenance free, sludge-free operation, low costs, sanitization and resource recovery, achieving harmless treatment. If fertilizer is not needed, the treated water can be directed to a subsequent greywater treatment tank, where it is treated together with greywater before being discharged up to standard.

    In the current "Toilet Revolution", the common approach is to convert dry toilets into flush toilets. However, the large daily flush water volume results in sewage staying in the 1.5-cubic-meter national standard septic tank for less than 30 days—insufficient to meet harmless treatment requirements and limiting resource utilization. This usually necessitates additional treatment facilities or sewage transportation to treatment plants, leading to high long-term operational and maintenance costs. 

    In the contrast, the combination of our ultra-low flush water closet(WC) and high-efficiency bio-bacterial strains decomposes solid or semi-solid sewage in the first compartment of the septic tank into liquid form. This liquid then overflows into the second compartment for further harmless treatment, meeting the national standard Sanitary Requirements for Fecal Sludge Sanitization and producing organic liquid fertilizer, which is finally stored in the third compartment for later use. 

Key Advantages of Our Model

1. The liquid fertilizer contains our bio-bacterial strains, which effectively prevent soil compaction.

2. The combination of odor-proof squat pans/toilets and our specialized bio-bacterial strains eliminates any odor. 

3. Our ultra-low flush water closet(WC) produces small daily flush water volume, and after harmless treatment, no sludge cleaning or transportation is required. Farmers can utilize the fertilizer themselves, resulting in zero long-term maintenance costs. 

    This model has been applied in demonstration projects in Yanchuan County (Shaanxi Province), Weiyuan County (Gansu Province), and Guannan County (Lianyungang City, Jiangsu Province), gaining high recognition from local authorities and villagers.