ElectrochemicalNutrient Recovery for the Food\u2013Energy\u2013WaterNexus at Municipal Wastewater Facilities: Multivariate Analyses ofSeasonal Sampling and Reactor Performance

Effects of two different nutrient loads on microalgal production, nutrient removal and photosynthetic efficiency in pilot-scale wastewater high rate algal ponds

Nutrient recovery from wastewater streams by microalgae: Status and prospects

Constructed wetland with Salicornia as a biofilter for mariculture effluents

Nutrient recovery from wastewaters by algal biofilm for fertilizer production part 1: Case study on the techno-economical aspects at pilot-scale

Shallow lakes are typically either in a clear water state with high abundance of submerged macrophytes or in a turbid state dominated by phytoplankton. A 10-week mesocosm experiment was set up to test the hypothesis that in a very shallow aquatic ecosystem impacted by very high nutrient loading, both submerged macrophytes and phytoplankton may be abundant. Nutrient levels, phytoplankton biomass (measured as chlorophyll a, Chl a), total suspended solids (TSS), inorganic suspended solids (ISS), and submerged macrophyte biomass were measured in three different treatments: DH (deep (1 m) water with very high nutrient loading), SH (very shallow (0.5 m) water with very high nutrient loading), and SL (very shallow (0.5 m) water with low nutrient loading). Of the three treatments, the DH mesocosms exhibited the highest nutrient, the TSS and ISS levels, the highest phytoplankton biomass, and the lowest submerged macrophyte biomass, while the lowest nutrient, the TSS and ISS levels, the lowest phytoplankton biomass, and the highest submerged macrophyte biomass were observed in the SL treatment. All measured parameters exhibited intermediate levels in the SH treatment. Our study demonstrates that in very shallow aquatic ecosystems with very high nutrient loading, submerged macrophytes and phytoplankton may persist in an intermediate but potentially unstable state with medium water clarity. These findings may contribute to the understanding of the mechanisms involved in regime shifts in shallow lakes.

Lake Spokane became hypereutrophic due to nutrient input from a municipal wastewater facility. Following a 1977 reduction in wastewater total phosphorus (TP) from about 5 to 0.5 mg/L, lake water quality and trophic state recovered rather quickly, going from hypereutrophy to meso-eutrophy in the first 7 years. After TP reduction, mean summer (Jun–Oct) inflow TP declined from 86 to 25 μg/L during that 7-year period. Mean summer epilimnetic chlorophyll (Chl) declined from 21 to 11 μg/L, and the mean volume-weighted (v-w) hypolimnetic seasonal minimum dissolved oxygen (DO) increased from 1.4 to 4.5 mg/L over that same period. Recent data (2010–2014) demonstrate continued recovery to meso-oligotrophy with the 5-year average minimum hypolimnetic v-w DO at 6.5 mg/L and mean inflow TP and epilimnetic Chl at 15 and 4 μg/L, respectively. The areal hypolimnetic oxygen deficit (AHOD) rate now averages 0.67 ± 0.12 g/m2 per day, which is 84% less than the pre TP-reduction AHOD (median 4.2 g/m2 per day). This recovery in DO indicators may be the clearest case of recovery from severe eutrophication for a reservoir, which usually have higher AHODs than lakes. The recovery confirms the close link among TP inflow concentration, Chl, and DO in reservoirs, despite their relatively large watersheds and inflows that produce high nutrient loadings compared to natural lakes. The results show that reduction of phosphorus recovered the lake to meso-oligotrophy, even though nitrogen was initially limiting as much or more than phosphorus during hypereutrophy, and despite markedly increased inflow nitrogen since 2000.

In the present study, a new dynamic fluidized bed reactor (FBR) model is developed to account for the effect of bubble growth in the bed height on the dynamic behaviour of the reactor and the molecular properties of the polymer product. The model takes into account the existence of solid catalyst in both phases and consequently, the occurrence of polymerization reaction in both bubble and emulsion phases. A dynamic two-phase model is employed for predicting the key hydrodynamic parameters of the bed. A comprehensive kinetic model for ethylene polymerization in the presence of multiple-site Ziegler-Natta catalyst is considered to describe the number and molecular weight averages and molecular weight distribution of polymer in the FBR. The hydrodynamic model and the kinetic model have been coupled and solved simultaneously to simulate the performance of the fluidized bed reactor. The study incorporates the effects of the most important reactor parameters such as superficial gas velocity, mean particle size, inlet gas temperature, bubble size, recycle stream and chain transfer agent on the steady-state behaviour of the FBR. The proposed dynamic model is capable of predicting both the performance of the reactor and the polymer physiochemical properties.

In the present study, a new dynamic fluidized bed reactor (FBR) model is developed to account for the effect of bubble growth in the bed height on the dynamic behaviour of the reactor and the molecular properties of the polymer product. The model takes into account the existence of solid catalyst in both phases and consequently, the occurrence of polymerization reaction in both bubble and emulsion phases. A dynamic two-phase model is employed for predicting the key hydrodynamic parameters of the bed. A comprehensive kinetic model for ethylene polymerization in the presence of multiple-site Ziegler-Natta catalyst is considered to describe the number and molecular weight averages and molecular weight distribution of polymer in the FBR. The hydrodynamic model and the kinetic model have been coupled and solved simultaneously to simulate the performance of the fluidized bed reactor. The study incorporates the effects of the most important reactor parameters such as superficial gas velocity, mean particle size, inlet gas temperature, bubble size, recycle stream and chain transfer agent on the steady-state behaviour of the FBR. The proposed dynamic model is capable of predicting both the performance of the reactor and the polymer physiochemical properties.

To protect human health and natural ecosystems, wastewater treatment plants (WWTPs) have been traditionally designed to remove pollutants from wastewater. With remarkable success WWTPs have adapted to increasingly stringent discharge limits over the years. Nowadays, municipal wastewater treatment facilities are facing a double transition. On the one hand, the transition towards sustainability and the circular water economy, in which resource recovery from wastewater (water recovery, energy recovery and nutrient recovery) plays a fundamental role for its effective implementation. Note that the incorporation of any resource recovery process in a WWTP will immediately turn it into a water resource recovery facility (WRRF). On the other hand, the digital transition, which aims at making the operation of these facilities smart and that undoubtedly could have a synergistic effect together with the paradigm shift towards the effective implementation of circular water economy. To make our current facilities smart, there is a growing interest in finding the way to convert the collected process data into intelligent actions for improving their operation. This is not an easy task for many reasons: - the harsh environment in which the instrumentation has to work (corrosive, sludgy, biofilm formation with biological activity…), - almost complete absence of metadata that would make it easy the interpretation of the process data that it is being collected and that would enable its future use, - the almost complete absence of automated data quality assurance, required to avoid “garbage in – garbage out”- the ever-increasing number of process sensors available (data overload), that must be properly processed and made easily available for further use to make them useful- large amounts of data are collected and stored in databases but not wisely used, thus, resulting in data graveyards, - the excessive cost of nutrient and organic matter sensors/analysers which moreover are labour maintenance intensive, fact that restrict their availability to the range of large facilities, thus, they are not usually available for small size facilities (which are the vast majority). - the intelligent sensors and data-driven models must be maintainable by the plant workers (not by Data scientists), - the lack of process expertise in the development of the artificial intelligent tools, - plant operators are often accustomed to their operational routines and, therefore, cultural change is needed in the organization for successful digital transition and adopting new intelligent tools. The progress in computing capabilities together with the large amount of collected process data in WWTPs have created the perfect storm for the machine learning boom we are observing, but all the aforementioned issues can make the incredible digital transition opportunity that exists today completely lost. In an attempt to avoid this disaster, this paper tries to shed light on the path towards increasing the value of the large amount of data that nowadays are being collected in WWTPs and WWRFs. Thus, digital transition could be safely embraced and the enormous potential of data analytics fully exploited, enabling it to play an essential role in the future automation and operation of our municipal facilities.

<abstract> <bold><sc>Abstract. </sc></bold>Treatment of waste streams using algae can minimize eutrophication by removing inorganic nutrients while producing biomass which can be used for biofuels, animal feed, and fertilizer production. While there are many studies that report the growth of individual algal strains in different media, there are relatively few studies that examine the performance of algae coculture. The objective of this research was to determine the growth parameters and nutrient sequestration profiles of Chlorella vulgaris, Scenedesmus dimorphus, and their coculture in wastewater from a dairy facility at two dilutions (10% and 25%). Average specific growth rates (and biomass concentrations) the S. dimorphus, C. vulgaris, and their coculture were 0.263 d^-1 (0.290±0.059 g/L), 0.063 d^-1 (0.145±0.011 g/L), and 0.250 d^-1 (0.400±0.060 g/L) d^-1 at 10% manure, and 0.232 d^-1 (0.543±0.149 g/L), 0.234 d^-1 (0.364±0.113 g/L), and 0.289 d^-1(0.612±0.255 g/L) at 25% manure, respectively. Based on the results it was evident that the strains S. dimorphus and C. vulgaris have different capacities for accumulation of biomass production (S. dimorphus is higher), lipid accumulation (S. dimorphus is higher), chlorophyll (C. vulgaris is higher), total suspended solids (TSS) (C. vulgaris is higher), and volatile suspended solids (VSS) (S. dimorphus is higher). It was found that mixed coculture had higher biomass growth, specific growth rate, and removal efficiency of nitrogen, phosphorous, and TSS for the 25% dairy wastewater. The results were similar for 10% dairy wastewater except for the specific growth rate and nitrogen removal efficiency which were higher for the S. dimorphus monoculture. These capacities can be leveraged in mixed coculture to achieve higher treatment efficiencies compared to monocultures. The results can inform managers of agricultural and municipal wastewater facilities as they make decisions about whether to include algal technology in future upgrades and expansion.

The production and consumption of energy are important driving forces for the economic and social development of a country, and environmental pollution caused by the consumption of energy especially for traditional energy has become a global focus in recent years. This paper analyzes the progress of energy production and consumption in China from 1957 to 2017 and characterizes the correlation between energy consumption and environmental pollution in China. Statistical methods, such as fit regression and gray relevance based on distance, are employed to describe their relations. It is shown that the total amount of energy production and consumption in China has steadily risen. Energy consumption has a strong link with environmental pollution, as demonstrated by its high correlations with the emission of waste gas and the generation of solid waste. The corresponding determination coefficients are 0.99 and 0.98, respectively. The results of the distance-based gray relevancy analysis indicate that, among all the correlations between different industrial wastes, the relation between discharged industrial solid waste and coal combustion is the largest (R = 0.79), while the relation between industrial solid waste and crude oil consumption is the smallest (R = 0.50). Compared to the other two wastes of the industry, energy consumption has the most impact on industrial wastewater, of which the average correlation coefficient is 0.61. The influence of coal combustion on environmental quality is the largest among the various energy consumption activities, with an average correlation coefficient of 0.76. Finally, the paper uses case analysis of remote sensing monitoring for environmental pollution to further discuss environmental problems. This study can provide necessary support for optimizing the domestic structure of energy consumption to further reduce pollution and improve environmental quality in China.

Commercial‐scale production of microalgae biomass for biofuel and biochemicals requires a substantial amount of water and nutrients. Many studies are conducted to explore the potential of various aqueous streams originating from harvesting stage and different energy recovery steps as an alternative for water and nutrient supply. Presence of toxic organic compounds, unassimilated ions, particulate matter, and high alkalinity in post‐harvest water limit its recyclability. Nutrient recovery from biomass via anaerobic digestion (AD) and various hydrothermal processes is being explored. So, there is a need to understand the impact of harvesting methods, nature and impact of organic compounds, buildup of algogenic organic matter (OM), amount of unused nutrients, and salinity on water recycling. Optimum conditions for maximum nutrient recovery from AD and hydrothermal processes are discussed for effective nutrient recycling. This review is an attempt to understand the challenges associated with the recycling of aqueous streams for water and nutrient requirement for sustainable microalgae cultivation. The effectiveness of a recycling stream is defined here as “biomass ratio.” Possible growth inhibiting factors are identified, and their solutions are suggested along with potential directions for future research. Large‐scale sustainable cultivation of microalgae through recycling of different streams depends on better understanding of biological activity of algal OM through detailed characterization and in‐depth understanding of physiochemical properties.

Electrochemical phosphorus leaching from digested anaerobic sludge and subsequent nutrient recovery

During the last decade, water reuse has been widely recognized in many regions of the world. Fouling of ceramic membranes, especially hydraulically irreversible fouling, is a critical aspect affecting the operational cost and energy consumption in water treatment plants. In addition, the reverse osmosis (RO) membranes, that are often used for water reuse plant, frequently face the problem of bio-fouling. The main objective of this thesis is to develop innovative applications of the ceramic ultra- and nanofiltration membranes for water reuse purpose. Improving RO pre-treatment using tight ceramic UF or ceramic NF To prevent the biofouling often relies on pre-treatment technology, since frequent chemical cleaning does not only increase the operational cost but also destructs the polyamide skin layer of RO membrane. A good RO pre-treatment should aim at both particulate removal to release clogging in the module, and organic carbon or nutrient limitation to release biofouling in the RO. Intense pre-treatment has been applied to alleviate the biofouling in RO membranes during wastewater reclamation. Whereas, current filtration-based pre-treatment processes cannot adequately prevent biofouling due to their poor removal of nutrients and organic carbon from feed water. The tight ceramic UF and ceramic NF membranes can potentially be deployed for RO pre-treatment in order to constrain the biofouling in RO by removing the organic carbon and phosphate (as nutrient). Theoretical research on the phosphate rejection by the charged tight ceramic UF was conducted, and the results have emphasized the importance of electrostatic interactions between the negatively charged membrane and the phosphate. The results indicate that the rejection of phosphate is dependent on the pH of the solutions and the results can be interpreted by Donnan exclusion and formation of an electrical double layer in the membrane pores. The greater phosphate rejection due to electrostatic repulsion results from a stronger overlapping of the electrical double layers in membrane pores. A Debye ratio (ratio of the Debye length to the pore radius) can be used to evaluate double layer overlapping in tight UF membranes. However, the membrane fouling caused by organic matter and cations can potentially influence the phosphate rejection by the tight ceramic UF. The phosphate rejection appeared to be linearly correlated to the surface charge of the organics in the feed waters. In addition, the biopolymers in WWTP effluent water organic matter (EfOM) can adsorb phosphate with the bridging of multivalent cations, which leads to higher phosphate rejection by the EfOM-fouled membranes than humics-fouled membranes. Sewer mining using ceramic nanofiltration Ceramic NF can be used for direct municipal sewage filtration aiming at energy, fresh water and nutrient recovery, so called sewer mining. Over 80% of organic carbon substrates and 90% of dissolved phosphate were rejected by a ceramic NF membrane (450 Da), but only 10% for ammonia. Concentration of the municipal sewage using ceramic NF increases the efficiency in the energy and nutrient recovery during the anaerobic digestion. The fouling on the ceramic NF membranes during sewage filtration can be suppressed by chemical cleaning with NaClO (0.1%) and HCl (0.1 mol L-1), while the cleaning of polymeric NF membranes is reportedly far more difficult. As such, sewer mining with ceramic NF is believed as an innovative and viable technology for energy, fresh water and nutrient recovery.

Hybrid technology for nutrients recovery as microbial biomass and ammonium sulfate from un-diluted biogas liquid digestate using a modified airlift reactor