The wastewater treatment equipment for dry toilet renovation is as follows:

I. Wastewater Treatment Equipment for Dry Toilet Renovation — Wastewater Treatment Methods

1. Physical treatment: Primarily intended for small-scale farmers, this method involves filtering or settling wastewater and using septic tanks and screens to remove suspended solids. Its drawback is that a significant amount of pollutants still remains, necessitating further treatment at a later stage; otherwise, the treated effluent will fail to meet regulatory standards.

2. Chemical treatment: This method is relatively costly. It involves the use of chemicals to dissolve or solidify pollutants in wastewater based on their chemical composition. Commonly used chemicals include disinfectants and coagulants; for example, ferrous salts may be added to wastewater to induce the flocculation and settling of suspended particles, thereby achieving water purification.

3. Biological Treatment: This is an environmentally friendly and cost-effective method that requires a lengthy treatment period. It relies on microorganisms to break down pollutants in wastewater, thereby purifying the water quality.

II. Wastewater Treatment Equipment for Dry Toilet Renovation—Selection and Determination of the Process

China has conducted extensive research and exploration into manure and wastewater treatment processes and technologies, carrying out numerous experiments and practical applications. As a result, effective and successful experience has been accumulated, gradually leading to the development of treatment processes that are primarily biochemical in nature, with combinations of biochemical and physicochemical approaches. Commonly used biochemical methods include the activated sludge process, biofilm processes, combined anaerobic–aerobic processes, hydrolysis–acidification, and aerobic treatment. Engineering practice has demonstrated that aerobic treatment of solid–liquid-separated manure wastewater is both feasible and effective for medium- and large-scale livestock farms, while the combination of hydrolysis–acidification and aerobic treatment is more suitable for small-scale farms. Anaerobic digestion not only reduces energy consumption and operating costs but also enables the recovery and utilization of biogas, thereby achieving waste valorization. The pulsed-influent upflow anaerobic acidification process has proven relatively stable in the actual operation of numerous treatment facilities and is currently one of the most widely adopted anaerobic treatment technologies. This scheme recommends the use of this particular anaerobic treatment process.

III. Wastewater Treatment Equipment for Dry Toilet Renovation — Wastewater Treatment by Sedimentation and Filtration

The purpose of sediment filtration is to remove suspended and colloidal particles from the water source. If these larger particles are not removed, they can damage precision filtration membranes during subsequent treatment stages and even cause blockages in the water flow paths. This is a very old and simple water purification method, which is why it is often used as a pretreatment step in wastewater treatment. If necessary, additional filters can be installed in the pipeline to remove larger-sized impurities. There are many types of filters used for removing suspended particles, such as sand filters, membrane filters, and mesh filters; these filters may be packed with quartz sand or other media. As long as the particle size exceeds the pore size of the filter, the particles will be retained and the filter will become clogged. Fine particulate matter and ions dissolved in the water, however, cannot be intercepted. If the filter is not replaced or cleaned regularly, more and more particles will accumulate on its surface, leading to reduced water flow and lower water pressure. Typically, the degree of filter clogging is assessed by measuring the pressure difference between the inlet and outlet. Therefore, filters should be cleaned and replaced on a regular schedule to remove accumulated contaminants.

Sediment filtration also presents a noteworthy issue. As particulate matter continuously clogs and accumulates on the filter membrane, bacteria can proliferate on these deposits and release endotoxins through the filter, triggering pyrogenic reactions and thereby causing some degree of damage to the filter itself. Consequently, filters must be replaced on a regular basis. Typically, replacement is required when the pressure drop between the influent and effluent reaches five times its original value.