Journal of Environmental Engineering

In this paper, a review of advances in total maximum daily load (TMDL) implementation planning by modeling best management practices (BMPs) and green infrastructure (GI) practices along with enhanced (hybrid/streamlining) approaches is presented. The review emanates from Chapter 12 of the recent ASCE Manual of Practice on TMDLs. The latest models and modeling tools, specifically the United States Environmental Protection Agency’s (USEPA’s) GI Modeling Toolkit and the Landscape and Green Infrastructure Design (L-GrlD) model for formulating GI strategies with flexibility to support stakeholder engagement, are reviewed. In addition, other decision support tools that can help advance the state-of-the-practice of TMDL implementation are included in the synthesis. Advances in incorporating model uncertainties related to BMPs and GI practices in TMDL analysis are briefly discussed. Furthermore, enhanced approaches to cost-effective TMDL implementation measures are discussed, which can be combined with other watershed management strategies for greater synergy between TMDL modelers and other watershed stakeholders. Some emerging technologies such as remote sensing can be useful for monitoring the effectiveness of the TMDL implementation measures over time. Several emerging technologies are discussed through an example illustrating the long-term efficacy of implementation practices. Finally, an enhanced approach to the full TMDL life cycle that explicitly incorporates BMPs and GI practices in the TMDL is proposed, and expected benefits of this approach are demonstrated with conceptual diagrams.

This study investigated the impact of food waste grinder (FWG) use on potable water consumption, wastewater characteristics, solid waste diversion, and resident attitudes in a multiunit residential building (MURB), which also provided source separated organics collection (green bins) to residents as a means to dispose of food waste. Baseline conditions were assessed during a four-month control period where residents had access to only green bins as a means to divert food waste from mixed solid waste, which was followed by an 11 month study period where residents had access to green bins and FWGs. No significant increase in potable water consumption was observed with FWG use. With the exception of fixed dissolved solids and fats, oils, and grease (FOG) (increases of 16% and 45%, respectively, though FOG was lower than typical wastewater), the generation of measured wastewater constituents did not increase significantly with FWG use. The variability of most wastewater constituent concentrations increased considerably after FWG activation, suggesting that widespread use of FWGs in MURBs may result in increased variability in the influent to wastewater treatment plants. The quantity of organics in the mixed solid waste stream did not decrease following FWG implementation, but the amount of unavoidable food waste present in the green bin stream decreased ($-20\%$), suggesting that materials disposed of in the FWG had been disposed of in the green bin stream prior to FWG activation. Resident survey respondents indicated using both devices for food waste disposal, with no device consistently preferred by the population. To our best knowledge, this was the first study to focus specifically on the impact of FWG implementation in a MURB population, which also had access to green bins as a means of disposing of organic waste.

Abstract

Microbial fuel cells (MFCs) are green technology capable of generating direct current while simultaneously treating wastewater. Although in most studies, catholytes used in MFC reactors are either phosphate buffer, direct oxygen or air cathodes. In this study, the effect of different organic loads in synthetic wastewater (equivalent to the organic load present in low- and medium-strength wastewater) as anolyte and acidic water as catholyte on cell voltage, current, power generation, and chemical oxygen demand (COD) removal efficiency with a mixed bacterial culture inoculum as biocatalyst have been accessed. Results showed a positive effect of using acidic water (pH 2) as catholyte with increasing organic load in each cycle on cell voltage, current density, and volumetric power density generation. Among all the cycles, Cycle 5 with $5.35\mathrm{g}/\mathrm{L}$ COD load generated highest cell voltage of 205.55 mV, continuous current density, and volumetric power density of $60.45\mathrm{mA}/{\mathrm{m}}^2$ and $84.50\mathrm{mW}/{\mathrm{m}}^3$, respectively, with 93.85% COD removal efficiency and 77.38% Coulombic efficiency (CE). Although none of the cyclic voltammograms (CVs) showed any oxidation peak but reduction peaks were observed in Cycles 3, 4, and 5 with 1.60, 3.21, and $5.35\mathrm{g}/\mathrm{L}$ organic load. Cycle 5 showed two sharp reduction peaks, which can be attributed to growth of mixed bacterial culture, and 16S microbiome profiling confirmed the dominance of two unclassified species, one of Sphingomonas and the other of Burkholderia, which may have contributed to the occurrence of the two sharp reduction peaks in Cycle 5. This study demonstrates that acidic water (pH 2) can be used as an effective catholyte along with species from Sphingomonas and Burkholderia genera in treatment of synthetic wastewater with COD equivalent to low- and medium-strength domestic wastewater and bioelectricity generation.

Practical Applications

Conventional wastewater treatment technologies are not sustainable to treat huge quantities of low- and medium-strength wastewater because they are cost-intensive and energy-driven processes that also release a large quantity of sludge, leading to sludge disposal problem. Moreover, they do not yield energy or any other valuable by-product. Results from our study shows that MFC can be effectively used to reduce 68.83% of total dissolved solids (TDS) and 93.85% of COD content of synthetic wastewater equivalent to low- and medium-strength wastewater, thereby efficiently treating the wastewater and also solving the problem of huge amounts of sludge generation and disposal. In the process of wastewater treatment, our study was also able to generate $84.50\mathrm{mW}/\mathrm{m}3$ of power density, making it an energy-yielding technology. Usage of an inexpensive mixed microbial culture inoculum as a biocatalyst (dominance of Sphingomonas and Burkholderia species) in this work showed that biocatalysts can be used as alternative to expensive metal catalysts in treatment of low- and medium-strength wastewater. During practical application of this study’s findings, synthetic wastewater can be replaced with any low- and medium-strength wastewater, be it of kitchen, domestic, or municipal origin, and acidic water as catholyte can be replaced with acidic wastewater effluents of any industry to simultaneously treat two type of wastewaters and generate bioelectricity.

The application of sodium alginate is limited because of its relatively small adsorption capacity, easy to release cations into water after forming gel with divalent cations, and difficult to realize mass production under the condition of controllable cost. In order to solve the aforementioned problems of sodium alginate gel, this study used activated carbon (AC) as a support material to enhance the mechanical properties of sodium alginate gel. Activated carbon-sodium alginate-oxalate gel particles (CSO) were used to increase the number of its oxygen-containing functional groups and improve the adsorption capacity. The specific surface area of the synthesized CSO particles could reach $\mathrm{1,413.568}{\mathrm{m}}^2·{\mathrm{g}}^{-1}$. The particle size of CSO particles was 50% in the range of 80–200 um, and 70% in the range of 40–200 um. The surface zero charge of CSO particles was determined to be 3.14. The thermal stability of CSO particles at 200°C was determined by thermal gravimetric analyzer (TGA). By studying the effects of different influencing factors on the process of removing pollutants from water by CSO, it was determined that pH has different effects for different pollutants. The equilibrium adsorption capacity ($q_e$) of CSO for Ni(II), Pb(II), and Cu(II) under the optimum condition of reaction temperature of 50°C was 77.14, 53.04, and $77.66\mathrm{mg}·{\mathrm{g}}^{-1}$, respectively. The adsorption isotherms were fitted to obtain the maximum adsorption capacity ($q_m$) of CSO for Ni(II), Pb(II), and Cu(II) as 75.56, 49.65, and $75.64\mathrm{mg}·{\mathrm{g}}^{-1}$. A combination of X-ray electron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) characterization demonstrated that the main mechanisms for the removal of divalent metal cations by CSO particles involved electrostatic adsorption and ion exchange. Overall, this work provides a good reference for the purification of heavy metal–polluted water by CSO particles.

Abstract

Sewer concrete structures are vulnerable to acidic corrosion due to the biological oxidation of sulfide in the wastewater to sulfuric acid. The use of photosynthetic bacteria in the coating layer on the sewer concrete is proposed to be an effective approach to prevent such corrosion. Here we report two strains, PN6 and PN7, isolated from a drainage system in Hanoi that were identified as Rhodopseudomonas palustris PN6 and Rhodobacter capsulatus PN7 based on a comparative analysis of the 16S rDNA and pufM gene sequences. Both strains performed versatile metabolic paths, including anoxygenic and microaerophilic phototrophy and aerobic chemotrophy, allowing them to adapt to the fluctuating sewer conditions. Furthermore, they exhibited notable capability of oxidizing sulfide and producing glycocalyx, and therefore were able to prevent concrete corrosion by scavenging sulfide and reducing the production of sulfuric acid, at the same time sealing the tiny cracks on the concrete surface and preventing further attack of the corrosive agents. Two strains grew well at an alkali pH of 9 and formed biofilm extensively, and therefore can be incorporated into porous material vermiculite, allowing them to survive in the coating mortar. The protective effect of coating mortar containing strains PN6 or PN7 singly or in a combination of both incorporated in vermiculite was demonstrated in a laboratory model simulating the sewer environment with an acidic vapor atmosphere. Without bacteria in the coating mortar, the concrete surface suffered severe corrosion with spots of 0.01–0.2 mm in width and up to 4.5 mm in length clustering in rafts of $10–70{\mathrm{mm}}^2$, whereas the concrete surface coated by bacteria-containing mortar was intact to corrosion. The study proposed the possibility of applying purple nonsulfur bacteria (PNSB) to protect sewer concrete, and also prolong the service life of these important structures.

Practical Applications

Sewer concrete systems are daily attacked by acidic corrosion established via the biological oxidation of sulfide to sulfuric acid. The repair is generally costly and has difficulties in implementation. The use of PNSB with the capabilities of scavenging ${\mathrm{H}}_2\mathrm{S}$ and producing exopolysaccharide (EPS) for the development of a coating layer would be a feasible approach to constrain the corrosion process. Suitable strains of PNSB such as the two strains Rhodopseudomonas palustris PN6 and Rhodobacter capsulatus PN7 reported in this study are supposed to be incorporated in a porous material like vermiculite before being added to the coating mortar to better stabilize and adapt to the harsh conditions of the coating layer. These types of PNSB can survive in the coating layer and multiply by utilizing organic carbon and sulfide from wastewater with the production of sulfur (instead of sulfuric acid) and glycocalyx that can instantly seal the tiny corrosion spots and prevent further corrosion attacks. This approach is supposed to be a prevention solution to increase the service durability of sewer concrete systems and reduce the need for repair implementation.

Abstract

The World Health Organization (WHO) estimates that microbiologically contaminated drinking water is estimated to cause 485,000 diarrheal deaths each year. Household water treatment is a low-cost method for reducing the pathogen load in drinking water to decrease instances of diarrhea and sometimes death. This study developed and evaluated a new silver and copper water treatment product that meets WHO one-star performance criteria for household water treatment without using electricity: the $\mathrm{MadiDrop}+\mathrm{Cu}$. First, we tested different configurations of a copper mesh and a copper screen with the MadiDrop to evaluate the effects of their proximity to one another on copper and silver concentrations in water. Wrapping the copper mesh around the MadiDrop decreased silver concentrations in water compared with the MadiDrop alone. Folding the copper screen into smaller dimensions decreased the copper concentrations in water compared with the copper screen unfolded. The MadiDrop and copper screen, coined $\mathrm{MadiDrop}+\mathrm{Cu}$, provided an average of $125–415\mathrm{\mu g}/\mathrm{L}$ copper and $4–21\mathrm{\mu g}/\mathrm{L}$ silver daily for 150 days of use. When tested individually and in combination against E. coli, $\mathrm{MadiDrop}+\mathrm{Cu}$ removed the most bacteria together rather than separately after 8 h. A previous study found a prototypic chlorinated polymer gel removed more E. coli with the MadiDrop than either intervention alone after 8 h. This study tested the viral (MS2 Bacteriophage) disinfection from the chlorinated polymer and $\mathrm{MadiDrop}+\mathrm{Cu}$ by themselves and in combination with one another. The MadiDrop alone removed $<1\log$ (90%) of viruses, whereas $\mathrm{MadiDrop}+\mathrm{Cu}$ removed $>3\log$ (99.9%) after 24 h. The greatest viral disinfection occurred when the $\mathrm{MadiDrop}+\mathrm{Cu}$ and chlorine-charged polymer gel were used together, removing $>4\log$ (99.99%) after 24 h.

Practical Applications

Low-cost and simple household water treatment products can be used in underresourced settings to prevent waterborne disease. This study designed and tested a novel approach to low-cost water treatment: combining a silver-embedded ceramic tablet with a high specific-surface-area copper screen and a chlorine-charged polymer gel. $\mathrm{MadiDrop}+\mathrm{Cu}$ was found to consistently release sufficient levels of silver and copper over 150 days of use. The MadiDrop alone killed less than 90% of viruses, whereas the $\mathrm{MadiDrop}+\mathrm{Cu}$ killed over 99.9% of viruses after 24 h. The MadiDrop, copper screen, and the chlorine-charged polymer gel killed over 99.99% of viruses after 24 h. Although a 24 h wait time is not ideal for emergency settings, the findings suggest that this novel approach to combining silver, copper, and chlorine without electricity is a promising method for a low-cost, household water treatment.

Abstract

Biochar is a carbonaceous material with pollutant removal abilities due to its characteristics, such as high surface areas resulting from small and large pores for adsorption. Biochar can be incorporated into best management practices (BMPs) as a performance-enhancing device (PED), treating pollutants such as nutrients, heavy metals, and suspended solids in highway stormwater runoff. In this study, three (3) commercial biochar products were purchased from different manufacturers and studied. In the end, the effective one was selected based on its ability to remove pollutants from highway stormwater runoff. A batch experimental setup was utilized for each biochar product and highway stormwater runoff pollutant parameter tested. Three (3) major analyses [chemical oxygen demand (COD), color, and total dissolved solids (TDS)] were selected to represent the biochar’s ability to remove oxidizable pollutants, color, and ions such as sodium (${\mathrm{Na}}^{+}$), magnesium (${\mathrm{Mg}}^{2+}$) and chloride (${\mathrm{Cl}}^{-}$) ions from the sampled highway stormwater runoff. Among the three (3) biochars studied, the Soil Reef Biochar showed relatively high and consistent removal of COD (82%), color (66%), and TDS (28%) from the highway stormwater runoff compared to the Wakefield Biochar and the Biochar Supreme products and therefore was selected as the effective one for further studies. The pH of the highway stormwater runoff treated with the three (3) biochar products was in the low basic range (7.95 to 9.01). The Wakefield Biochar showed a conductivity of $92.3\mathrm{\mu s}/\mathrm{cm}$ compared to the Soil Reef Biochar and the Biochar Supreme at 156 and $160\mathrm{\mu s}/\mathrm{cm}$, respectively. This study presented a comprehensive yet simple analytical method for selecting the effective biochar for highway stormwater runoff pollutants removal.

Practical Applications

Biochar has properties that make it an efficient material for pollutant removal in highway stormwater runoff. Some of these properties include a large surface area, higher pore volume with a variety of sizes, and high carbon content, allowing pollutant removal through adsorption. The adsorption treatment process allows the attachment of solute molecules (pollutants) in the water to the biochar. The large surface area and pore volume allow for greater adsorption of pollutants and therefore greater pollutant removal. The readily available feedstock materials from waste for biochar production ensure less expensive and sustainable green material for highway stormwater runoff treatment. Biochar products in the market currently are produced using different raw materials and different production and quality assurance methods. The knowledge on selecting or screening biochar to ensure efficient highway stormwater pollutant treatment is limited. To ensure the applicability of a certain commercial biochar product in the removal of highway stormwater runoff pollutants in a specific location, traffic volume, and pollutant composition, this study provides a method of general performance testing of the biochar product before field implementation or model studies. Based on the methods developed and the results obtained from this study, stormwater managers and other stakeholders from several agencies will be able to make informative decisions on biochar product selection.

Abstract

To reduce the operating cost of wastewater treatment plants and in situ treatment of sewage sludge and domestic food waste, the current investigation of anaerobic codigestion of domestic food waste and primary bioflocculated sewage sludge was conducted in an anaerobic reactor coupled with a decentralized domestic wastewater treatment plant. The performance of the anaerobic reactor and wastewater treatment system was tested for 30 days. The anaerobic digester was placed after the flocculation chamber in the wastewater treatment plant to transfer the primary bioflocculated sludge using gravity. The $0.5\mathrm{kg}{\mathrm{Day}}^{-1}$ of domestic food waste and $29\mathrm{L}{\mathrm{Day}}^{-1}$ of bioflocculated sewage sludge were used as feedstock for an anaerobic codigestion and supernatant collected in the flocculation chamber were passed to the water treatment stages. The bioflocculated sludge was collected by adding flocculant in domestic raw wastewater and fed in a digester whereas food waste was added using the separate port in the digester on daily basis. The anaerobic digester was operated in continuous mode at mesophilic temperature conditions at a hydraulic retention time of 7 days. The physiochemical parameters for controlling the anaerobic digester were examined periodically which showed the maximum volatile fatty acid accumulation of $\mathrm{6,500}\mathrm{mg}{\mathrm{L}}^{-1}$ on the 12th day with the highest biomethane production of $0.35\mathrm{L}{\mathrm{CH}}_4{\mathrm{g}}^{-1}{\mathrm{VS}}_{\mathrm{consumed}}$. The highest energy production potential of biogas was estimated as 0.35 kWh unit. The physical, chemical, organic, inorganic, and biological characteristics of treated water were tested to quantify the treatment efficiency of the process for the reuse of treated water. Results indicated that more than 90% of effluent was collected at the outlet of treatment units and the tested parameters were fulfilling the guidelines set by the different agencies for the reuse of effluent for various purposes.

Practical Applications

This paper investigates the performance of anaerobic codigestion of food waste and bioflocculated sewage sludge coupled with a decentralized wastewater treatment plant for the ease of substrate availability. Biomethane production was used to analyze the energy generation potential of domestic sewage sludge and food waste to reduce the operating cost of wastewater treatment systems. The feeding ratio used for operating the anaerobic reactor was decided based on food waste and sewage sludge availability from typical households. The limiting values of VFA with codigestion of food waste and bioflocculated sewage sludge have been reported in the current study and compared with literature values. This work provides insights to make possible the in situ treatment of domestic wastewater along with energy generation from food waste and bioflocculated sewage sludge in an integrated system which is unavailable in the literature.

Microalgae-bacteria consortium for wastewater treatment has great potential for use in nutrient removal and biodiesel acquisition. In this study, the effect of four different light/dark regimes ($6/18\mathrm{h}$, $12/12\mathrm{h}$, $18/6\mathrm{h}$, $24/0\mathrm{h}$) on biomass production and pollutant degradation during the treatment of oilfield wastewater by the algae-bacteria consortium was investigated. The maximum algal biomass ($0.2\mathrm{g}/\mathrm{L}$) and total chlorophyll content ($812.76\mu {\mathrm{gmg}}^{-1}$ cell dry ${\mathrm{weight}}^{-1}$) were obtained due to an appropriate illumination cycle ($18\text{hlight}/6\mathrm{h}$ dark) with enhanced dissolved oxygen content ($5.87\mathrm{mg}/\mathrm{L}$), thus improving bacterial biomass ($0.31\mathrm{g}/\mathrm{L}$). The ratio of microalgae to bacteria was essentially constant under different light/dark cycles. In addition, the highest removal rates of chemical oxygen demand (55.32%), ammonia nitrogen (50.75%), total nitrogen (64.53%), and total phosphorus (65.97%) were also obtained at the $18/6\mathrm{h}$ cycle, significantly different from the results of other light/dark cycles. The degradation efficiency of ammonia nitrogen by bacteria increased and then decreased with increasing light duration, while the removal rate of ammonia nitrogen by algae showed the opposite trend. The results indicated that the light and dark regimes had an important influence on the growth of the microalgae-bacteria consortium and their performance in treating oilfield wastewater.