Municipal Sewage Waste Research Articles

Consumer perceptions of the co-benefits of biosolids and carbon sequestration in a fertiliser aimed at the urban retail market

New markets for biosolids-derived products are urgently required to provide cost-effective solutions for water utilities to address the increasing production of municipal sewage waste. One potential outlet for biosolids is the domestic retail fertiliser market. Biosolids-derived fertilisers could be marketed to consumers by highlighting their environmental benefits, including carbon sequestration potential. This study used a two-part research approach to assess the feasibility of biosolids-derived fertiliser in the current market and to gauge the extent to which retail consumers value carbon sequestration features in fertilisers. First, a hedonic price analysis of existing fertilisers in the market explored consumer preferences and whether they currently pay extra for “sustainable” or “organic-certified” products. Second, a discrete choice experiment was designed to elicit consumers’ willingness-to-pay for biosolids-derived fertilisers and those clearly labelled with their carbon sequestration capability. The hedonic price analysis determined that organic or natural fertilisers sell at similar or slightly higher prices than synthetic alternatives. The choice experiment revealed that consumers would pay 17% more for fertilisers labelled with their carbon capture capacity. Purchasers of organic fertilisers perceived biosolids-derived fertilisers as valuable organic alternatives. In contrast, buyers of synthetic fertilisers were willing to pay slightly less for biosolids-derived alternatives. These findings suggest that some consumers are willing to purchase biosolids-derived fertilisers at prices comparable to current alternatives and place higher value on fertilisers offering environmental benefits, such as carbon sequestration. These results indicate that urban retail markets could be a strategic outlet for biosolids by producing biosolids-derived fertilisers.

Biomethane Potential of Selected Organic Waste and Sewage Sludge at Different Temperature Regimes

Sewage sludge (SS) generation and its management still pose a problem in many countries. Anaerobic co-digestion (AcD) of SS with grease trap sludge (GTS) and organic fraction of municipal sewage waste (OFMSW), which are two easily biodegradable substrates, may improve biogas production and AcD kinetics. Algae biomass (AB) of the species Undaria pinnatifida can be the third co-digestion component that may also affect the AcD performance. The aim of the study was therefore to evaluate the performance of mesophilic and thermophilic SS batch AcD with OFMSW, GTS as well as AB through biochemical methane potential (BMP) assay in relation to cumulative specific biogas (YB) and methane yields (Ym). Three kinetic models were applied within the scope of the kinetic study. Results of the study showed that the mixture containing SS, GTS and AB brought the most noticeable improvements in Ym compared to other studied mixtures and in respect to standalone SS digestion, the improvement amounted to 88.37% at mesophilic temperature (260.83 ± 15.02 N mL CH4/g-VSadd and for standalone SS 138.47 ± 4.70 N mL CH4/g-VSadd) and 71.09%, respectively, at the thermophilic one (275.66 ± 4.11 N mL-CH4/g-VSadd and for SS standalone 161.13 ± 13.11 N mL-CH4/g-VSadd).

Water Quality Assessment of a Water Body using Principal Component Analysis – Sanjay Lake, New Delhi, India

The present study aims at assessing the water quality at Sanjay Lake, Delhi, India using multivariate statistical techniques. A total of 16 physiochemical variables such as pH, conductivity, TDS, COD, DO, chloride, total hardness, magnesium hardness, phosphate, suspended solids, sulphate, nitrate, fluoride, sodium, potassium and calcium were analysed in water samples collected on January, 2020 from 10 sampling sites. The data were evaluated using IBM Statistics software SPSS 25 for principal component analysis, which limits the multiple data dimensions without the loss of vital information for better understanding. Five principal components were defined to be responsible for the data collection, indicating 93% of the total variance of data collection; of which 36.38% by PC1, 24.84% by PC2, 15.13% by PC3, 11.26% by PC4, and 6.36% by PC5 indicated that the domestic sewage, the municipal sewage waste and the untreated industrial effluent discharges may be affecting the water quality. The present study shows that PCA techniques are useful resources for the identification of important surface water quality parameters.

Synthesis of Diallyl dimethyl ammonium chloride grafted polyvinyl pyrrolidone (PVP-g-DADMAC) and its applications

The search for a sustainable and nontoxic polymeric product has fired an intense research in the field of graft copolymers. This study endeavor to create a polyacrylamide free novel flocculant which showed efficient behavior towards water and wastewater treatment and for mineral ore beneficiation. We synthesized the novel graft copolymer - Poly Diallyl Dimethyl Ammonium Chloride (DADMAC) grafted polyvinyl pyrrolidone (PVP-g-pDADMAC) via graft polymerization route by microwave assisted method. The synthesized novel cationic graft co-polymer has been characterized by elemental analysis, FTIR spectroscopy, intrinsic viscosity measurement, molecular weight determination, and scanning electron micrograph (SEM), taking PVP as reference. The effects of reaction parameters onto the percentage grafting have been studied. The applicability of these grafted polymers as flocculant for the treatment of municipal sewage waste water as well as for mineral ore beneficiation and for suppression of nanopollutant like multi-walled carbon Nano-tubes (MWCNTs) (as nano scavenger) from water systems were also investigated.

ВЛИЯНИЕ САНИТАРНО-ПАРАЗИТОЛОГИЧЕСКОГО ЗАГРЯЗНЕНИЯ ПОВЕРХНОСТИ ВОД В РЕСПУБЛИКЕ САХА (ЯКУТИЯ) НА ЗАБОЛЕВАЕМОСТЬ НАСЕЛЕНИЯ АКТУАЛЬНЫМИ ПАРАЗИТОЗАМИ

The article presents an analysis of the epidemic situation in the priority parasitosis of the population in the Sakha Republic. The research shows the influence of sanitaryparasitological contamination of surface water sources with propagative forms of pathogens of diphyllobothriosis, enterobiosis and ascaridosis on the helminthiases morbidity among the population. Water contamination of the Sakha water pools by municipal sewage waste, discharges of river vessels during the navigation period, invasiveness of fish by plero-cercoids of diphylobothriids, contamination of the population with diphyllobothriosis followed by contamination with eggs of diphyllobothriids of domestic sewage, – all the mentioned facts reveal circulation of the pathogen and confirm the presence of diphyllobothriosis in middle flow of the Lena river in the borders of the city of Yakutsk. The influence is exerted by the dissemination of communal sewage and, consequently, of surface water sources by the propagative forms of biohelminths on the epidemic disadvantage of the Yakutia population with diphyllobothriosis. Diphyllobothriosis is the dominant biogelmintosis in the region. The high level of enterobiosis (contact helminthiasis) infectiousness among the population and an insignificant incidence of ascaridosis (typical geogelmintosis), in our opinion, is due to sanitary and hygienic living conditions of the population and climatic and geographic features of the region.

A quantitative microbial risk assessment model for total coliforms and E. coli in surface runoff following application of biosolids to grassland

In Ireland, the land application of biosolids is the preferred option of disposing of municipal sewage waste. Biosolids provide nutrients in the form of nitrogen, phosphorus, potassium and increases organic matter. It is also an economic way for a country to dispose of its municipal waste. However, biosolids may potentially contain a wide range of pathogens, and following rainfall events, may be transported in surface runoff and pose a potential risk to human health. Thus, a quantitative risk assessment model was developed to estimate potential pathogens in surface water and the environmental fate of the pathogens following dilution, residence time in a stream, die-off rate, drinking water treatment and human exposure. Surface runoff water quality data was provided by project partners. Three types of biosolids, anaerobically digested (AD), lime stabilised (LS), and thermally dried (TD)) were applied on micro plots. Rainfall was simulated at three time intervals (24, 48 and 360 h) following land application. It was assumed that this water entered a nearby stream and was directly abstracted for drinking water. Consumption data for drinking water and body weight was obtained from an Irish study and assigned distributions. Two dose response models for probability of illness were considered for total and faecal coliform exposure incorporating two different exposure scenarios (healthy populations and immuno-compromised populations). The simulated annual risk of illness for healthy populations was below the US EPA and World Health Organisation tolerable level of risk (10−4 and 10−6, respectively). However, immuno-compromised populations may still be at risk as levels were greater than the tolerable level of risk for that subpopulation. The sensitivity analysis highlighted the importance of residence time in a stream on the bacterial die-off rate.

Novel Biodegradable Flocculating Agents Based on Grafted Starch Family for the Industrial Effluent Treatment

Grafting of acrylamide (AM), N,N-dimethylacrylamide (DMA) and a mixture of N,N-dimethylacrylamide and acrylic acid (AA) onto starch family namely Starch (St), amylopectin (AP) and hydroxyethyl starch (HES) were carried out by free radical polymerization technique in water medium. The so prepared graft copolymers were characterized by different characterization techniques. The flocculation characteristics of all the graft copolymers were performed in an industrial textile dye effluent, a paper mill waste water and municipal sewage waste water. Their flocculation performances were also evaluated in 0.25 wt% iron ore slime, 1.0 wt% kaolin clay, 1.0 wt% coal and 1.0 wt% silica suspensions separately. A comparative study was also made among the three graft copolymers in each series (St, AP and HES) in all the suspensions along with the real waste water. The flocculation characteristics of the best performing graft copolymer was also compared with some commercial flocculants like magnafloc 1011, telfloc 2230 and percol 181 in all the synthetic suspensions, industrial effluents and municipal sewage waste water. In coal, iron ore slime and silica suspensions and in municipal sewage waste water polysaccharide-g-PDMA showed best results but in kaolin clay suspension, in paper mill effluent and in textile dye effluent polysaccharide-g-(PDMA-co-AA) showed best performance. Among all the graft copolymers, graft copolymer based on HES showed best flocculation performance when compared to other graft copolymers as well as to some commercially available flocculants.

Using municipal biosolids in ecological restoration: What is good for plants and soil may not be good for endemic earthworms

Soil quality can be heavily impacted through large-scale anthropogenic disturbances such as mining and subsequent stockpiling of topsoil mixed with the rock removed to access the resources below. One potential source of nutrients and organic matter with which to rehabilitate such soils is dried and sterilised municipal sewage waste (biosolids). As this is subject to city-related contaminants, numerous studies have investigated its effects on growth and survival of flora and fauna that may be exposed, including earthworms. However, despite use of biosolids in mine soil rehabilitation, no study has examined the effects of biosolids on endemic earthworms; most focus on globally widespread or agricultural species and their role in ecosystem restoration. We tested the impact of soil remediation with municipal biosolids and endemic earthworms on plant growth, and carbon substrate utilisation as well as the direct impact of biosolids on endemic earthworm survival and growth. These measures were also compared to unmodified soil from a local pristine habitat not yet mined. Although biosolids treatment almost doubled plant biomass production and increased carbon substrate utilisation compared to untreated stockpiled or unmodified soils, earthworm mortality in biosolids-amended soils was 100%, compared with 42% and 25% in stockpiled and unmodified soils respectively. Earthworms significantly benefited soil functional diversity, but had no direct effect on plant growth. This study indicates that biosolids and endemic earthworms can play an important role in ecological restoration but thorough ecotoxicological testing of biosolids should be undertaken prior to their use in mine rehabilitation on a large scale.

Solubilization of municipal sewage waste activated sludge by novel lytic bacterial strains

Extracellular polymeric substances (EPS) are an extracellular matrix found in sludge which plays a crucial role in flocculation by interacting with the organic solids. Therefore, to enhance pretreatment of sludge, EPS have to be removed. In this study, EPS were removed with a chemical extractant, NaOH, to enhance the bacterial pretreatment. A lysozyme secreting bacterial consortium was isolated from the waste activated sludge (WAS). The result of density gradient gel electrophoresis (DGGE) analysis revealed that the isolated consortium consists of two strains. The two novel strains isolated were named as Jerish03 (NCBI accession number KC597266) and Jerish 04 (NCBI accession number KC597267) and they belong to the genus Bacillus. Pretreatment with these novel strains enhances the efficiency of the aerobic digestion of sludge. Sludge treated with the lysozyme secreting bacterial consortium produced 29 % and 28.5 % increase in suspended solids (SS) reduction and chemical oxygen demand (COD) removal compared to the raw activated sludge (without pretreatment) during aerobic digestion. It is specified that these two novel strains had a high potential to enhance WAS degradation efficiency in aerobic digestion.

Development of a novel, two-step process for treating municipal biosolids for beneficial reuse

Modern municipal sewage waste treatment plants use conventional mechanical and biological processes to reclaim wastewaters. This process has an overall effect of converting a water pollution problem into a solid waste disposal problem (sludges or biosolids). An estimated 10 million tons of biosolids, which require final disposal, are produced annually in the United States. Although numerous disposal options for biosolids are available, including land application, landfilling, and incineration, disposal costs have risen, partly because of increased federal and local environmental restrictions. A novel, thermomechanical biosolids pre-treatment process, which allows for a variety of potential value-added uses, was developed. This two-step process first employs thermal explosive decompression to inactivate or kill the microbial cells and viruses. This primary step also results in the rupture of a small amount of the microbial biomass and increases the intrinsic fluidity of the biosolids. The second step uses shear to effect a near-complete rupturing of the microbial biomass, and shears the nondigested organics, which increases the overall surface area. Pretreated biosolids may be subjected to a secondary anaerobic digestion process to produce additional fuel gas, and to provide for a high-quality, easily dewatered compost product. This novel biosolids pretreatment process was recently allowed a United States patent.

Constructive sludge management ‐ reutilization of municipal sewage sludge in Portland cement mortars

Abstract Sludges produced by the treatment of municipal sewage wastes are becoming increasingly difficult to dispose of because the quantity of sludge is increasing due to an increase in population and sewered areas. Many sludge disposal alternatives such as agricultural use, landfilling, marine disposal and incineration, etc, have adverse environmental impacts. There is a resulting increase of interest in reuse of sludge by incorporation into construction materials. In the present study, properties of digested, dewatered, dried and pulverized sludge blended Portland cement mortars are investigated. Sludge was used as replacement for 1, 2, 5, 10, 20, 30 and 40 percent by weight of the cement. The results indicate that initial and final setting times are longer with an increase of sludge. The mortar samples cast in standard moulds were cured for periods of 3, 7, 14 and 28 days before testing for compressive and tensile strength. The addition of 40 percent sludge caused the initial and final setting times of mortar to increase about 19 fold and 35 fold compared to control mortar with a water to cement ratio of 0.5. The effects of pulverized sludge on the Le Chatelier expansion and specific surface area of mortar are not significant. The addition of sludge adversely affected the compressive and tensile strength development. For 5 percent replacement of cement by pulverized sludge, the compressive and tensile strengths reduced by 32 and 38 percent, respectively.

Compressive Strength of Municipal Sludge Ash Mortars

Sludge ashes produced by the incineration of municipal sewage wastes are becoming increasingly difficult to dispose of in landfills, and there is a resulting increase of interest in disposal by inorporation in building materials. In the present study, a comprehensive test program was developed to examine the potential for using the ash as a fine aggregate in mortar. The strength characteristics of mortars prepared from sludge ash with addition of fly ashes (both Classes C and F) and varying amounts of cement and lime were cured under standard laboratory conditions for periods of 1, 3, 7, 14, and 28 days before testing for compressive strength. The results indicate that the addition of sludge ash adversely affects the strength behavior of mortars. Although partial substitution of sludge ash with fly ash gave improved results, strengths were always less than those obtained from control mortars using sand. Addition of fly ashes also improves mortar workability. The addition of lime in place of cement reduces strength.

Land Application of Municipal Sewage Waste Water: Yield and Chemical Composition of Forage Crops

AbstractAlfalfa (Medicago sativa L.) outyielded four grass species (reed canarygrass [Phalaris arundinacea L.], bromegrass [Bromus inermis Leyss.], Altai wildrye [Elymus angustus Trin.], and tall wheatgrass [Agropyron elongatum Beauv.]) when the forages were irrigated with sufficient lagooned municipal sewage waste water to meet the evapotranspiration minus precipitation deficit (about 50/cm per year). The yields were increased and the yield differential between the alfalfa and the grasses was reduced when additional N was added as fertilizer or by doubling the amount of waste water. The grasses, with the exception of tall wheatgrass, out‐yielded the alfalfa when fertilizer was added at the high waste water level. Since water did not limit growth, yields were controlled by the N supply. Waste water‐N and fertilizer‐N were equally effective in stimulating forage production.Nitrogen yield of alfalfa was double that of the grasses with the unfertilized waste water treatment, and considerably greater than the N yield of the grasses with the other treatments. Nitrogen uptake by all the forages, except tall wheatgrass, exceeded N application by waste water and fertilizer.Phosphorus application, in the waste water or as fertilizer P, exceeded plant uptake. The P content of the forage was unaffected by the treatment; thus, uptake was determined by the yield.Alfalfa was the most suitable forage crop when the system was operated for optimum utilization of the waste water. When high levels of waste water were applied, reed canarygrass removed most of the nutrients while withstanding flooding and higher soil moisture without stands being reduced by winterkilling, as occurred with alfalfa.