Anaerobic-ion exchange (AN-IX) process for local-scale nitrogen recovery from wastewater

Towards a sustainable transformation of municipal wastewater treatment plants into biofactories using advanced NH3-N recovery technologies: A review

Ammonia (NH3), as a prevalent pollutant in municipal wastewater discharges, can impair aquatic life and have a negatively impact on the environment. Proper wastewater treatment and management practices are essential to protect ecosystems and keep human populations healthy. Therefore, using highly effective NH3-N recovery technologies at wastewater treatment plants (WWTPs) is widely acknowledged as a necessity. In order to improve the overall efficiency of NH3 removal/recovery processes, innovative technologies have been generally applied to reduce its concentration when discharged into natural water bodies. This study reviews the current status of the main issues affecting NH3 recovery from municipal/domestic wastewater discharges. The current study investigated the ability to recover valuable resources, e.g., nutrients, regenerated water, and energy in the form of biogas through advanced and innovative methods in tertiary treatment to achieve higher efficiency towards sustainable wastewater and resource recovery facilities (W&RRFs). In addition, the concept of paradigm shifts from WWTP to a large/full scale W&RRF has been studied with several examples of conversion to innovative bio-factories producing materials. On the other hand, the carbon footprint and the high-energy consumption of the WWTPs were also considered to assess the sustainability of these facilities.

Advanced removal of phosphate from water by a novel lanthanum manganese oxide: Performance and mechanism

A novel lanthanum manganese oxide (La_0.96Mn_0.96O₃, LMO) was synthesized for advanced phosphate removal to alleviate water eutrophication process. The adsorbent had a specific surface area of 18.51 m²/g with pH at point of zero charge of 6.6; exhibited excellent phosphate adsorption capacity of 168.4 mg/g; performed well in a wide pH range from 3 to 10. The phosphate removal was not interfered by coexisting ions. The adsorbent remained 94.8% of its initial adsorption efficiency after reused for four times. Phosphate adsorption process conformed to pseudo-second-order model (R²=0.992) and Langmuir model (R²=0.935). Ligand exchange and electrostatic interaction played important roles in phosphate removal. In addition, the actual sewage secondary effluent was used to further verify the phosphate removal performance of LMO. For practical water treatment, the LMO showed high phosphate removal efficiency of 83.4% and low residual P of 0.1 mg/L. LMO is a potential candidate for low-concentration phosphate removal in real water environment.

Advanced phosphate and nitrogen removal in water by La-Mg composite

A novel La-Mg composite was prepared for the removal of low concentration phosphate and ammonium nitrogen to alleviate the eutrophication problem. The composition and morphology of La-Mg composite was characterized; Its surface was composed of La, Mg, C, and O elements, with a specific surface area of 21.92 m²/g. La-Mg composite presented excellent removal of phosphate (100%) and nitrogen (96.8%), and the adsorption capacity reached 49.72 mg-P/g and 159.30 mg-N/g for separated adsorption. The composite also had a wide pH usability range (3-11 for P and 3-9 for N) and the adsorption process was almost not disturbed by coexisting ions. After adsorption, it could be regenerated by Na₂CO₃ and reused effectively. For actual water treatment, a very low residual P of 0.01 mg/L and N of 0.05 mg/L were achieved. Furthermore, Mechanism analysis showed that P adsorption involved ligand exchange and electrostatic attraction. The potential mechanisms of N adsorption involved electrostatic attraction and ion exchange. The results showed that the La-Mg composite is a novel and efficient adsorbent for actual water treatment to achieve ultra-low nutrients concentration.

A critical review on ammonium recovery from wastewater for sustainable wastewater management

The growing global population's demand for ammonium has triggered an increase in its supply, given that ammonium plays a crucial role in fertilizer production for the purpose of food security. Currently, ammonia used in fertilizer production is put through what is known as the industrial Haber Bosch process, but this approach is substantially expensive and requires much energy. For this reason, looking for effective methods to recover ammonium is important for environmental sustainability. One of the greatest opportunities for ammonium recovery occurs in wastewater treatment plants due to wastewater containing a large quantity of ammonium ions. The comprehensively and critically review studies on ammonium recovery conducted, have the potential to be applied in current wastewater treatment operations. Technologies and their ammonium recovery mechanisms are included in this review. Furthermore the economic feasibility of such processes is analysed. Possible future directions for ammonium recovery from wastewater are suggested.

Local-scale recovery of wastewater nitrogen for edible plant growth

An anaerobic/ion exchange (AN-IX) system was developed for recovery and reuse of wastewater nitrogen at point-of-origin. AN-IX combines upflow solids blanket anaerobic treatment with ammonium ion adsorption onto granular natural zeolite. AN-IX operates passively and without energy input. A 57 L empty-bed prototype was operated for 355 days on wastewater primary effluent. Total nitrogen removal exceeded 95% over the first 214 days of operation and ammonia reduction exceeded 99%; accumulation of oxidized nitrogen species (NO3(-) + NO2(-)) was not observed. The wastewater flowrate was increased during the last 35 days of operation to deliberately exhaust the ion exchange media. Spent granular media was removed from the AN-IX prototype and deployed in plant chamber experiments for cultivation of Solanum lycopersicum (cherry tomato). Wastewater nitrogen captured on zeolite was capable of supplying the total growth requirement for nitrogen. Canopy volume and plant flowering and fruiting were higher for wastewater nitrogen than for artificial fertilizer. The AN-IX process is a passive, mechanically simple and reliable system for local-scale nitrogen recovery. AN-IX is modular, scalable, adaptable and can be applied in diverse treatment contexts and recycling scenarios. AN-IX benefits include appropriate technology for local-scale nitrogen recovery, low capital and energy costs, and protection of health and the environment.