Anaerobic digestion of raw and thermally hydrolyzed wastewater solids under various operational conditions

In this study, high-solids anaerobic digestion of thermally pretreated wastewater solids (THD) was compared with conventional mesophilic anaerobic digestion (MAD). Operational conditions, such as pretreatment temperature (150 to 170 degrees C), solids retention time (15 to 20 days), and digestion temperature (37 to 42 degrees C), were varied for the seven THD systems operated. Volatile solids reduction (VSR) by THD ranged from 56 to 62%, compared with approximately 50% for MAD. Higher VSR contributed to 24 to 59% increased biogas production (m3/kg VSR-d) from THD relative to MAD. The high-solids conditions of the THD feed resulted in high total ammonia-nitrogen (proportional to solids loading) and total alkalinity concentrations in excess of 14 g/L as calcium carbonate (CaCO3). Increased pH in THD reactors caused 5 to 8 times more un-ionized ammonia to be present than in MAD, and this likely led to inhibition of aceticlastic methanogens, resulting in accumulation of residual volatile fatty acids between 2 and 6 g/L as acetic acid. The THD produced biosolids cake that possessed low organic sulfur-based biosolids odor and dewatered to between 33 and 39% total solids. Dual conditioning with cationic polymer and ferric chloride was shown to be an effective strategy for mitigating dissolved organic nitrogen and UV-quenching compounds in the return stream following centrifugal dewatering of THD biosolids.     

Mining and the environment: a case study from Bijolia quarrying site in Rajasthan, India

Mining is essentially a destructive developmental activity, where ecology suffers at the altar of economy. Unfortunately, in most regions of the Earth, the underground geological resources are superimposed by biological resources (forests). This is particularly evident in India. Hence mining operations necessarily involve deforestation, habitat destruction, biodiversity erosion and destruction of geological records which contain information about past biodiversity. Extraction and the processing of ores and minerals also lead to widespread environmental pollution.However, mankind cannot afford to give up the underground geological resources which are the basic raw materials for development. An unspoiled nature can provide ecological security to people but cannot bring economic prosperity. Scientific mining operations accompanied by ecological restoration and regeneration of mined wastelands and judicious use of geological resources, with search for eco-friendly substitutes and alternatives must provide the answer.A case study from the Bijolia quarrying area in Rajasthan, India, provides some sensational revelations of the impact of mining on the human ecosystem.     

Fly-ash induced synthesis of phytochelatins in chickpea (Cicer arietinum L.) plants

Phytochelatins and related metabolites (cysteine and GSH) were found to be induced in the shoots of two varieties of Cicer arietinum viz., CSG-8962 and C-235 grown under different amendments of fly-ash with garden soil and press mud. Cysteine, GSH, PCs and its speciation were found in higher concentrations in amended fly-ash than in the control 100% soil. Two species of metal binding peptides i.e., PC2 and PC4 were found in both varieties and in amendments, however, their concentration varied depending upon the fly-ash concentrations in both amendments. Further, var. CSG-8962 was found more tolerant than var. C-235 because of higher concentrations of PCs and related metabolites.     

Determination of hierarchical relationships among sustainable development goals using interpretive structural modeling

This paper analyses the complex interactions among the seventeen sustainable development goals (SDGs) and presents them in a hierarchical framework using interpretive structural modeling technique. The driving and dependence powers of each of these goals have been ascertained to help the developing and least developed countries improve their strategic orientation for a particular goal within a given time frame. This would also help them in prioritizing their resource allocations on a specific SDG by focusing on its hierarchical ranking on one hand and driving and dependence powers on the other.     

Arsenic contamination: a potential hazard to the affected areas of West Bengal, India

Arsenic contamination in groundwater is becoming more and more a worldwide problem. Nearing 50 million of people are at health risk from arsenic contamination at Ganga–Meghna–Bramhaputra basin. The experimental results of the five blocks under Malda district of West Bengal, India, showed that the arsenic concentration in groundwater (0.41–1.01 mg/l) was higher than the permissible limit for drinking water (0.01 mg/l) (WHO) and FAO (Food and Agriculture Organization) permissible limit for irrigation water (0.10 mg/l). The soil arsenic level (13.12 mg/kg) crossed the global average (10.0 mg/kg), but within the maximum acceptable limit for agricultural soil (20.0 mg/kg) recommended by the European Union. The total arsenic concentration on food crops varied from 0.000 to 1.464 mg/kg of dry weight. The highest mean arsenic concentration was found in potato (0.456 mg/kg), followed by rice grain (0.429 mg/kg). The total mean arsenic content (milligrams per kg dry weight) in cereals ranged from 0.121 to 0.429 mg/kg, in pulses and oilseeds ranged from 0.076 to 0.168 mg/kg, in tuber crops ranged from 0.243 to 0.456 mg/kg, in spices ranged from 0.031 to 0.175 mg/kg, in fruits ranged from 0.021 to 0.145 mg/kg and in vegetables ranged from 0.032 to 0.411 mg/kg, respectively. Hence, arsenic accumulation in cereals, pulses, oilseed, vegetables, spices, cole crop and fruits crop might not be safe in future without any sustainable mitigation strategies to avert the potential arsenic toxicity on the human health in the contaminated areas.     

印度露天采矿的回填要求和制约因素

印度的大多数采矿活动都发生在生态敏感地区.本文讨论了一项回填（即用挖出来的物质填矿井）研究计划的结果.在一些情况下，由于技术限制，回填法的使用不得不被部分或全部放弃.也有许多费用方面的考虑.制定一条国家改造采矿用地战略是最根本的策略.     

Determining the effectiveness of conventional and alternative coagulants through effective characterization schemes

Polymeric forms of metal coagulants in water treatment have become increasingly used due to their wider availability and reduction in cost. These specialized coagulant forms and products are claimed by manufacturers to be superior to conventional coagulants in particulate and/or organic removal with inherent advantages of lower alkalinity consumption and lesser sludge production. However, due to their proprietary nature, little is known about their chemical composition. To determine and understand the effectiveness of these alternative coagulants, a comprehensive study was undertaken to characterize metal coagulants, and to comparatively evaluate them on a well-characterized source water. The objective of this study was to provide a scheme for utilities that could be employed as a screening process and a method of selecting an appropriate coagulant based on raw water characteristics and insight into the coagulatability of the source water. Characterizations of coagulants included: (i) active metal content, (ii) anion content, (iii) acidity, (iv) alkalinity consumption, (v) charge reversal by colloidal titration, and (vi) molecular weight determination. A total of five poly-aluminum chlorides (PACl), along with a conventional coagulant (aluminum sulfate or alum) were evaluated. Results show that through the characterization scheme, an effective coagulant (conventional versus alternative) and coagulant type (among various PACl) can be chosen before undertaking time-consuming bench or pilot-scale evaluation.     

Impact assessment of treated/untreated wastewater toxicants discharged by sewage treatment plants on health, agricultural, and environmental quality in the wastewater disposal area

Studies were undertaken to assess the impact of wastewater/sludge disposal (metals and pesticides) from sewage treatment plants (STPs) in Jajmau, Kanpur (5 MLD) and Dinapur, Varanasi (80 MLD), on health, agriculture and environmental quality in the receiving/application areas around Kanpur and Varanasi in Uttar Pradesh, India. The raw, treated and mixed treated urban wastewater samples were collected from the inlet and outlet points of the plants during peak (morning and evening) and non-peak (noon) hours. The impact of the treated wastewater toxicants (metals and pesticides) on the environmental quality of the disposal area was assessed in terms of their levels in different media samples viz., water, soil, crops, vegetation, and food grains. The data generated show elevated levels of metals and pesticides in all the environmental media, suggesting a definite adverse impact on the environmental quality of the disposal area. The critical levels of the heavy metals in the soil for agricultural crops are found to be much higher than those observed in the study areas receiving no effluents. The sludge from the STPs has both positive and negative impacts on agriculture as it is loaded with high levels of toxic heavy metals and pesticides, but also enriched with several useful ingredients such as N, P, and K providing fertilizer values. The sludge studied had cadmium, chromium and nickel levels above tolerable levels as prescribed for agricultural and lands application. Bio-monitoring of the metals and pesticides levels in the human blood and urine of the different population groups under study areas was undertaken. All the different approaches indicated a considerable risk and impact of heavy metals and pesticides on human health in the exposed areas receiving the wastewater from the STPs.     

Oxidative stress induced by HCH in Hydrilla verticillata (l.f.) Royle: modulation in uptake and toxicity due to Fe

The effect of hexachlorocyclohexane (HCH) singly and in combination with iron was studied on chlorophyll, malondialdehyde, cysteine, total -SH contents and potassium ion leakage in the plants of Hydrilla verticillata. The effect of HCH was also studied on glutathione (reduced and oxidised) content and superoxide dismutase activity. The results showed an increase in malondialdehyde content and potassium ion leakage with increase in HCH concentrations, however, the presence of Fe played a protective role. The chlorophyll content was decreased with increase in HCH concentrations and exposure period. However, the chlorophyll content at 2 and 5 microg ml(-1) was significantly higher in HCH-treated plants as compared to HCH + Fe after 168 h, showing protective role of Fe. The results showed significant increase up to 1 microg ml(-1) in cysteine content with increase in concentrations in both the treatments. The total -SH content was increased with increase in concentrations in both the treatments. In HCH-treated plants, non-significant change was noticed in reduced glutathione (GSH) content however, oxidised glutathione (GSSG) content was increased significantly after 168 h, indicative of oxidative stress. In addition, superoxide dismutase activity was increased non-significantly with increase in HCH concentrations. The accumulation of HCH singly and in presence of Fe was concentration- and duration-dependent. The accumulation of HCH was decreased in presence of Fe at higher concentrations. In contrast, the accumulation of Fe was increased in presence of HCH at higher concentrations. The results showed that malondialdehyde content and potassium ions leakage are the primary responses of toxicity.     

The design of blanket wash solvents with environmental considerations

The search for new solvents is often driven by (a) the need to replace solvents whose continued use pose a threat to environmental health and safety, (b) the needs of new applications and processing requirements, (c) a response to changing environmental regulations and (d) a response to market demands. For example, many traditional solvents are on the environmental ‘hit list’ and are to be phased out within the next few years. In particular, cleaning solvents, which are used as blanket washes in the lithographic printing industry present a number of environmental concerns including health and safety. To respond to these concerns and more importantly to respond to rapidly changing operational requirements and market forces, there is a need for efficient and systematic strategies for ‘just in time’ optimal design of solvent alternatives. A good strategy has to consider simultaneously, performance objectives, system interactions and environmental constraints. The object of this paper is to identify and discuss the issues in the design of cleaning solvents (blanket washes) in the printing industry and how environmental and health factors can be accounted for. We do this in the context of a framework for product design. As a proof-of-concept, blanket wash solvents are designed.